IMMUNOLOGY TEXTBOOK - Mercury Podillya 2013

IMMUNOLOGICAL RESEARCH METHODS

Study of cytokine synthesis at the single-cell level

Immunocytochemistry. METABOLISM/2.html">THE CONCEPT OF localizing Antigens in Tissues using Antibodies was first implemented in the early 1940s. Subsequently, immunocytochemical Methods became widely used in molecular clinical Diagnostics, and since the mid-1970s, following the discovery of Monoclonal Antibodies, their role has grown even further.

Immunocytochemical (ICC) methods allow for the localization and identification of cellular components (in our case, cytokines) based on their binding to antibodies. The binding site is determined using labeled antibodies or secondary labeling methods.

Preparations for ICC can be of three types:

a) Touch preps (imprints);

b) smears obtained by appropriate cytological or hematological methods;

c) preparations obtained by centrifugation of Cell Suspensions. The latter method is preferred when the researcher has biological fluids with a low cell count.

Tissue sections are prepared and incubated in a solution containing antibodies against the antigen of interest (cytokine). The antibody is often conjugated with a fluorescent dye so that the antigen localization can be visualized. Once the antibody finds the antigen and forms a complex with it, unbound antibodies are washed away, and the fluorescent dye remains at the sites of antigen localization. Using a spectrophotometer or fluorescence Microscope, one can determine the Location OF THE fluorescent dye and, consequently, where within The Cell the antigen is situated.

The reasons for the widespread use of ICC are obvious: a wide Selection of quality Reagents, ease of Structure/175.html">Implementation and training of personnel in result evaluation skills, and, in the case of light Microscopy, The ability to correlate with Morphology, store and transport preparations, and the absence of The Need for highly specialized equipment. The negative aspects include the subjectivity of visual assessment, difficulties in organizing quality control, the inability to account for A large number of Cells, and, consequently, the likelihood of an inadequate assessment of low-cell populations.

ELISpot. The ELISpot (Enzyme-Linked ImmunoSpot) assay is a highly sensitive Modification of the ELISA method that allows for the quantification of cells secreting a specific cytokine. The high sensitivity of the ELISpot method is due to the fact that the product at the time of analysis is located On the surface of the secreting cell, bound to its receptors. Furthermore, The stimulation of cytokine production occurs in vitro immediately prior to detection. As a result, ELISpot can detect 1 cytokine-secreting cell out of 100,000, which is 20–200 times more precise than standard ELISA.

Protocol of the ELISpot method:

1. Cytokine-specific antibodies are coated onto the bottom of a PVDF microplate.

2. Unbound sites are blocked using a protein.

3. Cells are added with or without an activator. During incubation, the cells are activated and begin to produce and secrete cytokines, which specifically bind to the primary antibodies.

4. The cells are washed.

5. Secondary antibodies, either enzyme-conjugated or biotinylated, are added.

6. When using biotin, a conjugate is additionally added.

7. A substrate is added, resulting in a colored spot at the location of the cytokine-secreting cell.

8. By counting the number of spots using an ELISpot Reader AID in the test samples and controls (without activator), the number of cells producing a specific cytokine is determined.

Flow Cytometry. This is the leading method in clinical immunology. It can be used to assess intracellular cytokine production by various cell populations.

Flow cytometry allows for the assessment of cytokine production at the single-cell level using intracellular staining. The combination of intracellular and surface staining provides maximally detailed information about the producer cell—its Class, subclass, and functional activity. The basal level of cytokines in resting cells is quite low; therefore, cells are pre-stimulated in vitro in the presence of cytokine production Inducers and Intracellular Transport blockers (brefeldin A, monensin). Subsequently, surface markers are stained, cells are fixed and permeabilized, and antibodies against intracellular markers are added. Next, the cells are placed into the flow cytometry sample container, where they are injected under pressure into the center of a co-axial sheath fluid stream flowing in the same direction through a specially designed tip. As a result, the speed of the cells increases sharply and they align into a single file surrounded by the sheath fluid. The geometry of the tip creates laminar flow conditions for the sample stream, preventing the suspension of test cells from mixing with the liquid. Upon entering the instrument's measuring chamber, the cells sequentially intersect a laser beam and are excited by light of a specific wavelength. In turn, the cells emit light signals of a different wavelength which, passing through a system of optical lenses, filters, and dichroic mirrors, are detected by a photomultiplier tube that converts these light signals into electrical signals processed by a computer. Two or three fluorescent signals, each reporting the reaction of a single monoclonal antibody with a specifically recognized antigen, can be collected from the cells along with forward scatter (FSC) and side scatter (SSC) signals. Light scatter signals characterizing cell size (FSC), as well as cytoplasmic and membrane features (SSC), link the fluorescence analysis to specific cell populations. The obtained data can be recorded, analyzed, and presented as histograms. In the case of a univariate histogram, the abscissa represents the fluorescence intensity of the cells, and the ordinate represents the number of cells with a given fluorescence intensity. By summing up the obtained data across the entire cell population of the sample, precise quantitative population and subpopulation analyses can be performed.

Determination of cytokine concentrations in biological fluids by enzyme-linked immunosorbent assay. Solid-phase enzyme-linked immunosorbent assay, or ELISA (Enzyme-Linked Immunosorbent Assay), is used for the analysis of monoclonal antibodies. This is a method for detecting The formation of immune complexes—antibody with antigen.

Assay Procedure:

1. First, the monoclonal antibodies (mAbs) are pre-immobilized on the inner surfaces of the wells of a solid-phase ELISA microplate.

2. Add 100 µL of standards to the first two vertical rows of plate wells as follows: A – 0 pg/mL of the target cytokine, B – 50 pg/mL, C – 250 pg/mL, D – 500 pg/mL, E – 1000 pg/mL, F – 2000 pg/mL. Add 100 µL of the test samples to the remaining wells. Both samples and standards should be added using the recommended buffers. Incubate the microplate for 1.5 hours at 18–20 °C. After incubation, discard the solution from the wells using a pipette. Next, wash the wells three times by adding 300 µL of wash buffer to each. Remove any residual wash solution with a pipette.

3. Add 100 µL of biotin-labeled secondary mAbs to each well and incubate the samples with them for 1.5 hours at +18 °C under continuous shaking. After incubation, remove the solution from the wells using a pipette. Wash the wells three times by adding 300 µL of wash buffer to each. Remove the remaining wash solution.

4. Add 100 µL of streptavidin-horseradish peroxidase conjugate (diluted 1:100 with buffer) to each well of the microplate and incubate at +18 °C with continuous shaking for 1 hour. After incubation, remove the solution from the wells. Prepare the tetramethylbenzidine (TMB) substrate solution 10–15 minutes before the incubation ends. After removing the solution, wash the microplate wells three times with 300 µL of wash buffer and 3–5 times with distilled Water, discarding the liquid by tapping the plate over a sink. These steps form a "sandwich" complex consisting of the following layers: the captured antibody, the sample (cytokine), and the enzyme-linked antibody.

5. Add 200 µL of tetramethylbenzidine (TMB) solution. Incubate for 20 minutes at room Temperature in the dark. Stop the reaction by adding 50 µL of 1 N sulfuric acid. The Enzymatic Cleavage of the substrate results in a color change. This color development indicates the presence of the cytokine in the sample. The results, reflecting The activity of the bound peroxidase, are quantified using an automated microplate photometer at a wavelength of 492 nm, Setting the zero absorbance against the standard wells lacking the target cytokine in the solution. Quantitative evaluation is performed by constructing a calibration curve that plots optical density against antibody concentration. The sensitivity of the method using domestic test systems is 5–30 pg/mL.

Advantages of the enzyme-linked immunosorbent assay (ELISA): high sensitivity; capability of using minimal sample volumes; long-term storage stability of all reagents required for the assay (up to a year or more); ease of performance; availability of both instrumental (Qualitative and quantitative) and visual readout methods; potential for automation at all Stages of the reaction; and relatively low cost of diagnostic kits.

Study of cytokine Gene Expression. Cytokines are signaling molecules of The Immune System. The expression level of these Proteins is of critical diagnostic value for selecting Immunomodulatory therapy and predicting the intensity and direction of the Immune Response. To determine which cytokines are synthesized and in what quantities, the PCR method is widely applied.

The Polymerase Chain Reaction (PCR) is a technique that mimics natural DNA Replication, allowing the detection of a few specific DNA molecules amidst millions of others. The method is based on the repeated, selective in vitro copying of a specific DNA region using Enzymes under artificial conditions. Consequently, only the target region that meets specific criteria is copied, and only if it is present in the test sample. PCR is used to amplify relatively short DNA fragments. In a standard PCR procedure, the length of the amplified DNA segments does not exceed 3,000 Base Pairs. Using a mixture of various polymerases, specific additives, and optimized conditions, the length of a PCR fragment can reach 20,000–40,000 nucleotide pairs.

Laboratory PCR analysis is performed in three stages: 1) DNA extraction; 2) Amplification of DNA fragments; 3) detection of amplified DNA products.

DNA extraction is the initial stage of PCR diagnostics, which involves the following procedure: a clinician collects a biological sample from a patient and subjects it to specialized Processing. During this process, the double-stranded DNA helix is split into individual strands. A specialized solution is added to dissolve Organic compounds that interfere with the "purity" of the reaction. Lipids, Amino Acids, Peptides, CARBOHYDRATES, proteins, and Polysaccharides are removed in this manner, ultimately yielding purified DNA or RNA.

DNA amplification, and thereby the core principle of PCR, is based on the natural biological process of DNA elongation and replication, which is achieved by doubling single DNA strands.

Starting with a single DNA fragment, the laboratory technician copies it and multiplies the number of copies through a chain reaction: after the first cycle, there are 2 fragments; after the second, 4; after the third, 8; after the fourth, 16, followed by 32, 64, 128, 256... The number of copies doubles with every cycle, reaching the millions after twenty cycles and the billions after thirty. Each cycle takes only a few minutes and involves precise temperature cycling within a small chemical Reactor. The solution contains an adequate supply of all necessary synthesis components—primarily NUCLEOTIDES—alongside subtle preliminary chemical preparations to ensure that an exact copy is immediately made from each ready DNA segment, followed by a copy of that copy. This is The Essence of the cascading chain reaction.

By attaching primers to the DNA strand, two short, double-stranded DNA helical regions are formed, which are essential for the Synthesis of the future DNA.

The synthesis of the new strand proceeds through the extension of each of the two DNA templates. The amplification process is driven by a specialized enzyme called DNA polymerase, applied in a laboratory setting. The polymerase acts as a reaction catalyst, ensuring the sequential attachment of nucleotide bases to the growing new DNA strand.

Thus, DNA amplification represents a manifold increase in the number of specific DNA copies. All repetitive amplification cycles occur at different temperatures. PCR analysis utilizes specialized programmable equipment—a PCR thermal cycler or amplifier—which automatically regulates temperature shifts. Amplification is carried out according to a preset program corresponding to the specific type of infection being detected. Depending on the program and the target infection, automated PCR takes about 2 to 3 hours.

During the detection of amplification products, the resulting mixture of amplified products is separated. Special solutions are added to the mixture, endowing the DNA fragments with fluorescent properties that appear as orange-red bands.

Analysis of cytokine gene polymorphisms. Investigating genes that control cytokine activity and act as inflammatory mediators is a crucial task in uncovering the pathogenetic mechanisms underlying the initiation and progression of diseases, as well as in identifying early disease predispositions. Understanding their role in the Pathogenesis of numerous conditions allows clinicians, on the one hand, to predict the risk of pathological development or disease severity, and on the other hand, to individually tailor specific therapy for each patient.

The expression of pro-inflammatory cytokines is under strict Genetic control. Let us examine the functional polymorphism of the TNF-α gene. The TNF-α gene is located on the sixth chromosome (6p21.3) within the locus encoding class I (HLA-A, B, C) and class II (HLA-DP, DQ, DR) Major Histocompatibility Complex molecules. Its location in the central region of The Genome accounts for the high Variability of this locus; specifically, the TNF-α promoter region contains eight polymorphic sites with single nucleotide substitutions: -1031T/C, -863C/A, -857C/T, -575G/A, -376G/A, -308G/A, -244G/A, and -238G/A. However, two are considered the most clinically significant in humans: single nucleotide substitutions of guanine for adenine at positions -308 (G>A) and -238 (G>A), which alter TNF-α production levels and are therefore functional. Positions -308 and -238 reside within the promoter, affecting the ability of Transcription factors to bind to this region of the gene and thereby influencing transcription rates. The -308 polymorphism increases the transcriptional activity of the TNF-α gene and, consequently, cytokine production. The highest transcription rate of the polymorphic TNF-α gene (-308*A) occurs in macrophages, where it is 5 times higher than that of the normal -308*G gene. Given that macrophages are the primary source of TNF-α, their genetically predetermined capacity for enhanced production of this pro-inflammatory cytokine can influence The Development of the body's inflammatory and immune responses.

Another polymorphic site in the TNF-α gene that affects cytokine production is position -238. However, in this case, the substitution of guanine for adenine leads not to an increase, but to a decrease in protein production. Specifically, stimulation of whole Blood Cells with lipopolysaccharide demonstrated that cells with the -238GA genotype synthesize 1.5 times less TNF-α than cells with the -238GG genotype.

In rheumatoid Arthritis, the leading role in pathogenesis belongs to the pro-inflammatory cytokines IL-1β and TNF-α. Studies have shown that patients carrying the -308G/A genotype of the TNF-α gene experience a more severe course of rheumatoid arthritis compared to those carrying the G/G genotype. Patients with the G/A allele exhibited an earlier disease onset, higher disease activity, and a greater number of erosions. Conversely, in other patient populations, this allelic variant of the TNF-α gene did not affect the severity or course of rheumatoid arthritis and showed no association with the disease. Investigation of the IL-1β gene polymorphism at position (+3953 C>T) in exon 5 revealed that the T/T genotype (A2A2 allele) is associated with more active rheumatoid arthritis compared to the C/C and C/T genotypes. Other data indicate that the presence of the T allele at this locus is associated with a higher joint erosion count in rheumatoid arthritis and elevated GENE EXPRESSION IN vitro.

One of the most severe consequences of bacterial infection is septic Shock. TNF-α serves as the primary endogenous mediator in the development of septic shock. At high concentrations, it triggers endothelial activation, leading to vasodilation, a drop in blood pressure, disseminated intravascular coagulation (DIC syndrome), multiple organ dysfunction syndrome (MODS), and thermoregulatory failure, collectively resulting in a fatal outcome. Genotyping of pediatric patients demonstrated that the presence of at least one copy of the highly active -308*A allele in a child's genotype increases the risk of mortality by 2.5-fold. Mortality among children with the -308 polymorphic genotype (AG, AA) was 3 times higher compared to carriers of the homozygous normal variant (-308 GG) of the TNF-α gene. The same applies to asthma: the G-to-A substitution at position -308 is associated with increased production of this cytokine, raising the risk of autoimmune pathology. Furthermore, a correlation has been identified between an increased frequency of the IL-10 -592A allele and Sepsis severity, the development of multiple organ failure, and a high probability of a fatal outcome.

HIV-infected patients exhibit several differences compared to healthy control groups regarding the frequency of cytokine gene allelic combinations. These include the presence of the A/A homozygous variant of the IL-10 gene (RR = 2.36), which was not detected in healthy individuals, and the absence of the A/A homozygous variant of the TNF-α gene (RR = -12.25), which was found in 4% of healthy women. The frequency of the A/G variant of the TNF-α gene is four times higher in patients (RR = 4.67) due to a decreased frequency of both homozygous variants.

The IL1RN gene encodes IL-1RA and is localized on chromosome 2. Carriage of the IL1RN*2 allele is associated with elevated levels of circulating IL-1RA and increased mRNA expression during inflammation. The impact of polymorphisms in the IL1B gene (encoding IL-1β) and IL1RN on the inflammatory profile can be described by the following tendencies: carriage of non-mutant variants of these genes determines adequate production of the corresponding proteins and proper Regulation of the IL-1 system. In individuals with a genetically predetermined bias toward IL-1β production, inflammation proceeds more acutely; in those with a bias toward IL-1RA production, the inflammatory response is more prolonged, which may contribute to the chronic progression of inflammation. Plasma IL-1RA levels are coordinately and jointly regulated by the IL1B and IL1RN genes, and carriage of IL1RN*2 is responsible for elevated levels of both circulating IL-1RA and IL-1β, with enhanced activation of expression and production resulting from excessive IL-1RA synthesis. According to this model, during the inflammatory response in individuals with a genetic predisposition toward IL-1RA production, The amount of this protein exceeds what is necessary for an adequate inflammatory reaction, triggering a compensatory production of even greater amounts of IL-1β. In turn, this induces an increased counter-production of IL-1RA as well. Thus, carrying combinations of IL1B and IL1RN genes that favor IL-1RA production leads to a more prolonged inflammatory response.

Therefore, studying gene polymorphisms as a factor of genetic predisposition to various human pathologies opens new avenues for identifying risk groups and selecting the optimal therapeutic strategy for individual patients. In the future, we can anticipate the advent of preventative methods to correct predispositions to a wide spectrum of diseases.

Clinical significance of cytokine determination. Because cytokines act as local mediators, it is advisable to measure their levels in target tissues following the extraction of tissue proteins from organ biopsies, or in biological fluids such as urine, tears, gingival crevicular fluid, bronchoalveolar lavage fluid, vaginal secretions, ejaculate, cavity washings, CEREBROSPINAL FLUID, or synovial fluid.

Additional information regarding the state of the body's immune system can be obtained by studying the in vitro cytokine production capacity of blood cells. There are two subpopulations of CD4+ T-helper cells—type 1 and type 2 T-helper cells—which share the same antigenic structure: type 1 and type 2 T-helpers (Th1 and Th2) express identical differentiation antigens CD3, CD4, CD29, and CD45RA. At the same time, Th1 and Th2 cells differ in the set (profile) of cytokines they synthesize in response to antigenic stimulation, and this profile dictates which of the two main TYPES OF IMMUNE response—cellular or humoral—will be mounted.

Type 1 T-helpers produce interleukins-2, 3, 12, IFN-γ, and TNF-β, as well as GM-CSF; they trigger the activation of cellular Immunity, the generation of cytotoxic T lymphocytes, natural killer cells, macrophages, and delayed-type hypersensitivity T-effectors. Th1 cells mediate immunity against Viruses, intracellular Bacteria, and oncogenic cells. The activity of Th1 is suppressed by interleukin-10.

Type 2 T-helpers produce interleukins 4, 5, 6, 10, and 13, which activate the HUMORAL IMMUNE RESPONSE, B lymphocytes, and allergic inflammation. By stimulating plasma cells to produce IgM, IgG4, and IgA IMMUNOGLOBULINS, Th2 cells provide immunity against common (extracellular) bacteria and their toxins. The activation of eosinophils and mast cells, along with the stimulation of immunoglobulin E (IgE) synthesis, leads to the development of allergies. The activity of Th2 is suppressed by IFN-γ.

Plasma cytokine levels reflect the Current state of the immune system and the progression of defensive reactions in vivo. Spontaneous cytokine production by peripheral blood mononuclear cell cultures makes it possible to assess the baseline activity of these cells. Elevated spontaneous cytokine production indicates that the cells have already been activated by an antigen in vivo. Induced cytokine production allows for the evaluation of the potential capacity of specific cells to respond to antigenic stimulation. Conversely, a reduced in vitro cytokine induction may serve as a sign of an immunodeficient state. Therefore, examining cytokine levels in both circulating blood and cell culture supernatants is crucial for characterizing overall immunoreactivity and the function of individual Components of the immune system. Furthermore, to assess disease severity and predict clinical outcomes, it is advisable to measure the concentrations of both pro- and anti-inflammatory cytokines dynamically throughout the course of the pathology.

Sepsis is the result of a dangerous, tissue-damaging host response to infection. It develops when the initial Immune Response to an infection becomes amplified and uncontrollable. Cytokines play a leading role in driving the mediator mechanisms of sepsis. Because sepsis involves the dysregulated expression of various cytokines, correcting macrophage dysfunction with immunomodulators requires a comprehensive approach that evaluates cytokine imbalances and analyzes their levels dynamically. TNF-α and IL-1β are considered to play a pivotal role in triggering the generalized inflammatory cascade during sepsis.

A modern therapeutic approach for sepsis involves cytokine therapy using Roncoleukin in combination with Antibiotics. For subcutaneous injections, no more than 0.25 mg of the drug is administered per injection site. Most patients respond adequately to this therapy without any complications. Only a few patients experience short-term chills with a brief temperature spike to 38–39 °C, moderate acrocyanosis, and mild euphoria. Other adverse events are typically absent. The development of such reactions indicates the activation of cytokine reactivity and represents an appropriate immune response to the administration of recombinant IL-2. As the microbial load decreases, macrophages begin to synthesize IL-10 and soluble TNF-α receptors. Their action aims to suppress the generalized inflammatory reaction. One month after completing the Treatment course, a decrease in pro-inflammatory cytokine production is observed.

Autoimmune diseases (AIDS) represent a class of clinically heterogeneous disorders that develop as a result of the pathological production of autoantibodies or the proliferation of autoaggressive killer cell clones directed against healthy, normal body tissues, leading to tissue damage, destruction, and the development of autoimmune inflammation. The core mechanism in the onset and progression of AIDs is the recognition of the body's own structures as foreign by immunocompetent cells, followed by their activation, proliferation, and the induction of inflammation. It is widely accepted that cytokines are essential elements in the pathogenesis of AIDs.

Rheumatoid arthritis is a chronic systemic inflammatory disease of the Connective Tissue characterized by progressive involvement primarily of the peripheral (synovial) joints, presenting as a symmetric, progressive, erosive-destructive polyarthritis.

Monocytes and macrophages play a crucial role in the development of rheumatoid inflammation. The synovial fluid and joint tissues in rheumatoid arthritis contain excessive amounts of TNF-α and IL-1β alongside minimal levels of T-cell cytokines (IL-2, -3, and -4, IFN-γ). TNF-α and IL-1β can enhance the expression of adhesion molecules on the vascular endothelium of the synovial membrane and their leukocyte ligands, induce the synthesis of chemotactic factors (IL-8 and monocyte chemotactic protein), and stimulate The production of fibroblast growth factor and inflammatory mediators. TNF-α and IL-1β are actively synthesized within the synovial membrane primarily by Cells of the monocyte-macrophage Lineage. IL-1β and TNF-α are potent inducers of IL-6 synthesis, which acts on hepatocytes to drive the hyperproduction of acute-phase proteins (C-reactive protein, amyloid protein, fibrinogen, etc.). Along with IL-1β, IL-6 contributes to the development of periarticular Osteoporosis. Mast cells also play a major role in the pathogenesis of rheumatoid arthritis: by releasing histamine, IL-4, and IL-6, they stimulate T AND B lymphocytes, whereas mast cell-derived heparin activates macrophages. Through IL-1β and TNF-α, mast cells interact with synoviocytes, whose subsequent proliferation is accompanied by the synthesis of PGE2. Concurrently, enzymatic systems capable of destroying Cartilage are activated.

Reducing TNF-α levels can modulate synovial cell apoptosis and inhibit synovial hyperplasia. Neutralization of TNF-α lowers the concentration (by binding and inhibiting the synthesis) of interleukin-1 (IL-1), IL-6, IL-8, monocyte chemoattractant protein-1, nitric oxide, metalloproteinases (collagenase, stromelysin), and other inducers of inflammation and tissue destruction, as well as the levels of soluble adhesion molecules such as ICAM-1 and E-selectin (which reflect vascular endothelial activation), thereby achieving an immunosuppressive effect.

The adjunctive administration of anti-TNF-α antibodies (infliximab, adalimumab), soluble TNF-α receptors (etanercept), or lymphocyte-lowering immunomodulators (leflunomide) to disease-modifying antirheumatic drugs (such as methotrexate and sulfasalazine) is associated with reduced arthritis activity, characterized by a decrease in the number of swollen and tender joints and an improvement in the patient's subjective well-being.

Asthma. Type 1, 3, and 4 immune reactions contribute to the shaping of the immune response in the airway inflammation observed in asthma patients, with type 1 mechanisms predominantly driving the process. Determining cytokine production by peripheral blood mononuclear cells (PBMCs) under in vitro stimulation is more informative than measuring plasma cytokine levels. Upon in vitro activation by agents such as phytohemagglutinin (PHA) and bacterial lipopolysaccharide (LPS), PBMCs secrete a broad spectrum of pro-inflammatory cytokines into the culture medium. Pronounced spontaneous cytokine production by PBMCs indicates that the cells have already been activated in vivo or during handling. Induced cytokine production makes it possible to assess the cells' activation potential.

When investigating spontaneous and standard mitogen-induced (PHA and E. coli LPS) cytokine production in whole blood supernatants, it was demonstrated that:

1. The spontaneous production of the pro-inflammatory cytokine IL-1β is decreased compared to healthy controls, whereas spontaneous IL-1β production in asthma patients in remission is significantly higher than during an exacerbation.

2. The ratio index of PHA-induced to LPS-induced IL-1β production is significantly lower in individuals with acute asthma exacerbation than in those in remission, and these values are also markedly reduced compared to healthy controls.

3. Spontaneous production of IL-10 is significantly elevated during asthma exacerbations compared to both asthma patients in remission and healthy controls.

4. A significant increase in IL-10 levels in asthma patients during exacerbation was also observed for both PHA-induced and LPS-induced IL-10 production when compared to the other two groups.

5. Calculation of the ratio index of PHA-induced IL-10 production to spontaneous production revealed a statistically significant decrease in patients with acute asthma compared to the healthy control group.

These findings demonstrate that cytokine synthesis and activation in asthma depend on the disease phase. During an exacerbation, an imbalance between pro- and anti-inflammatory cytokines is observed; the level of the anti-inflammatory cytokine IL-10 rises as part of the body's effort to dampen the inflammation.

Systemic lupus erythematosus (SLE). Cytokines play a critical role in the development of SLE. IL-10 production is markedly elevated in SLE, and the levels of IL-1β and TNF-α are likewise increased, correlating with disease activity. Furthermore, the production of anti-DNA autoantibodies is blocked by anti-IL-10 antibodies.

Infectious diseases. It is well established that HIV infection—In addition to compromising the T-cell arm of immunity and causing polyclonal activation of the humoral arm—disrupts the normal cytokine balance and cytokine network functioning. In the pathogenesis of HIV infection and AIDS, the imbalance of cytokines produced by Th1 and Th2 lymphocytes and monocytes plays a central role, influencing the potency of the immune response to specific viral antigens. The cytokine network is implicated in virtually all stages of virus-cell interaction, HIV dissemination within the macroorganism, immunodeficiency development, and opportunistic infections. In the Cytology/cytology/16.html">Early stages of HIV infection, there is an elevation in pro-inflammatory cytokine levels, which act as Cofactors for HIV activation. This cytokine imbalance facilitates viral infection of CD4+ cells, driving the progression of immunosuppression and the subsequent development of opportunistic infections. Research has established that TNF-α levels are significantly elevated in HIV-infected patients, facilitating HUMAN IMMUNODEFICIENCY VIRUS replication. Conversely, IL-10 and IL-1RA can reduce HIV replication by inhibiting the production of the pro-inflammatory cytokines IL-1β and TNF-α. As the disease progresses toward AIDS, a shift toward the predominance of IL-10 is observed: interleukin levels drop during stages III and IVA, followed by a rising trend in stage IVB and a statistically significant increase in the AIDS stage (stage V). Thus, the pathogenesis of HIV infection is characterized by chronic immunological dysfunction, resulting in the hyperproduction of pro-inflammatory cytokines. An objective Assessment of the parameters characterizing the immune system's efficacy in combating HIV and controlling viral replication can, with a certain degree of confidence, determine individual disease prognoses even during early asymptomatic stages, thereby enabling the initiation of intensive preventive therapy in individuals with unfavorable prognoses.