IMMUNOLOGY TEXTBOOK - Mercury Podillia 2013

CONGENITAL IMMUNE DEFICIENCY

Diagnosis of Primary Immunodeficiencies

A thorough medical history is taken and a physical examination is performed. This helps to identify which part of The Immune System is primarily compromised and to plan Laboratory tests. The physical examination is crucial for evaluating the effectiveness of Treatment for immunodeficiencies. Primary immunodeficiencies are typically congenital and manifest During the first year of life.

Medical History. Recurrent respiratory tract infections are a hallmark manifestation of immunodeficiencies. The most common pathogens include Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, Neisseria spp., Pseudomonas aeruginosa, as well as certain anaerobic Bacteria. In early childhood, frequent upper respiratory infections (up to 6-10 times per year) can occur even in the absence of an immunodeficiency—for instance, in children with allergic airway diseases who attend daycare or have older siblings in school. The specific Characteristics of Respiratory infections in immunodeficiencies are outlined below.

- A chronic course with complications, such as chronic suppurative otitis media, mastoiditis, Bronchiectasis, Pneumonia, meningitis, and Sepsis.

- Protracted exacerbations and resistance to standard treatment.

- Severe bacterial infections. Any recurrence of a severe infection warrants a thorough evaluation to rule out immunodeficiency. Recurrent severe Infections caused by Neisseria spp. indicate a deficiency in Complement components involved in The formation of the membrane attack complex.

- Infections caused by opportunistic microorganisms (Pneumocystis carinii, Aspergillus fumigatus, Candida albicans, Serratia marcescens), which are characteristic of Cell-mediated Immunity and phagocytic deficiencies.

A history of atopic conditions (particularly in the family) is atypical for immunodeficiencies.

Growth retardation. Growth delay is frequently observed in patients with immunodeficiencies, although its absence does not rule out the Diagnosis. It is most characteristic of children with cell-mediated immune deficiencies, especially when accompanied by chronic diarrhea. Other contributing factors to growth delay in immunodeficiencies include chronic infections.

Chronic diarrhea, frequent vomiting, and malabsorption syndrome can occur in any immunodeficiency and are typically caused by infections with Giardia lamblia, Cryptosporidium spp., Helicobacter pylori, enteropathogenic strains of Escherichia coli, or Viruses such as rotaviruses or cytomegalovirus. Alternative causes of gastrointestinal disturbances—such as disaccharidase deficiency, celiac disease, or gastrointestinal lymphoma—must be excluded.

Detailed information regarding past illnesses, previous treatments, sexual history, and drug use is essential. Particular attention should be paid to the following aspects.

Maternal illnesses during Pregnancy.

Gestational age and birth weight. Preterm infants born at less than 30-32 weeks of gestation exhibit hypogammaglobulinemia due to insufficient transplacental transfer of maternal IgG. Low-birth-weight infants are more susceptible to infections.

Complications from Blood component transfusions. Transfusing blood products in patients with cell-mediated immune deficiencies can trigger graft-versus-host disease.

Vaccination with live viral Vaccines can cause severe infectious complications in patients with cell-mediated immune deficiencies.

Antimicrobial therapy. It is important to determine the frequency and efficacy of prior antimicrobial therapy, as well as whether the patient received normal or specific IMMUNOGLOBULINS.

Surgical interventions. Recurrent respiratory infections often lead to surgical Procedures such as tonsillectomy, adenoidectomy, or sinus drainage. Retrospective histological analysis of resected palatine and pharyngeal Tonsils can reveal pathological changes characteristic of immunodeficiencies, such as the absence of germinal centers or plasma Cells.

Sexual history and risk factors—such as Sexually Transmitted Infections, sexual assault, or substance abuse—increase the risk of HIV infection, which may clinically mimic a primary immunodeficiency.

Family history. The inheritance patterns of primary immunodeficiencies are summarized in Table 47.

Class="center">Table 47. Inheritance Patterns of Primary Immunodeficiencies

Note: RFLP - restriction fragment length polymorphism; AR - autosomal recessive; XL - X-linked; (a) - insufficiently studied.

The majority of primary immunodeficiencies are inherited in an autosomal recessive or X-linked manner. When taking a family history, it is advisable to check for consanguinity and perform a pedigree analysis. Primary focus should be given to the following information.

- Cases of infant mortality, recurrent and chronic infections, hemoblastosis, and autoimmune diseases in close and distant relatives.

- Allergic diseases and cystic fibrosis in family members indicate that recurrent infections in a child are most likely unrelated to primary immunodeficiency.

Race and ethnicity. Certain conditions, such as Sickle cell anemia, are particularly prevalent among specific racial groups. Identifying these disorders in family members also suggests that frequent infections in a child are not associated with immunodeficiency.