Primary immunologic deficiency diseases are estimated to affect 1 in 4000 individuals; many are genetically determined and present in childhood. Nonetheless, several important immunodeficiency disorders present in adulthood, most notably the antibody deficiency syndromes: selective IgA deficiency, common variable immunodeficiency, and specific (functional) antibody deficiency (Table 20–14). Antibody deficiency predisposes patients to recurrent infections, particularly of the respiratory tract, including refractory chronic rhinosinusitis, bronchitis, pneumonia, and bronchiectasis. Patients are most susceptible to infections with encapsulated bacteria (eg, Haemophilus influenzae type b, Streptococcus pneumoniae, Neisseria meningitides). However, any part of the innate or adaptive immune system can be defective and results in infections with different spectra of organisms.
Table 20–14.Selected primary immunodeficiency syndromes. ||Download (.pdf) Table 20–14. Selected primary immunodeficiency syndromes.
|Disease ||Clinical Presentation ||Diagnosis1 ||Treatment |
|Selective IgA deficiency || |
Most prevalent primary immunodeficiency; most cases asymptomatic
Recurrent sinopulmonary infections; atopic disorders, rheumatoid arthritis, and SLE common; rarely, anaphylaxis to transfusion of blood or blood products
|Undetectable serum IgA levels (< 7 mg/dL), normal serum IgG and IgM levels || |
Early use of antibiotics for bacterial infections
Prophylactic antibiotics for symptomatic patients with recurrent infections
|Common variable immunodeficiency || |
Most common symptomatic primary immunodeficiency disorder
Recurrent sinopulmonary infections, parasitic (especially Giardia lamblia) gastrointestinal infections, autoimmune diseases, and increased risk of malignancy
|Low serum IgG, low serum IgA and/or IgM; poor antibody response to immunizations; exclusion of secondary causes of hypogammaglobulinemia || |
Subcutaneous or intravenous immunoglobulins
|Complement disorders || |
“Early” complement component deficiencies: autoimmune diseases
“Late” complement component (C5–C8) deficiencies: recurrent meningococcal or gonococcal infections
|Screen with CH50 and AH50. Obtain individual serum complement levels if abnormal ||Prompt administration of antibiotics |
|Granulocyte disorders || |
Recurrent invasive skin and soft tissue infections, abscesses requiring incision and drainage
Common organisms are Staphylococcus aureus, gram-negative bacilli, Nocardia, Aspergillus
CBC with differential to evaluate neutrophil count
Dihydrorhodamine assay to evaluate neutrophil oxidative burst
|Antimicrobial prophylaxis; interferon in patients with chronic granulomatous disease |
1. SELECTIVE IgA DEFICIENCY
Selective IgA deficiency is the most common primary immunodeficiency disorder and is characterized by undetectable serum IgA levels (lower than 7 mg/dL) with normal levels of IgG and IgM; its prevalence is about 1 in 500 individuals (Table 20–14). Most affected individuals are asymptomatic. A minority of patients have recurrent infections such as sinusitis, otitis, and bronchitis. Selective IgA deficiency can be associated with atopic diseases and autoimmune disorders, including Graves disease, SLE, juvenile rheumatoid arthritis, type 1 diabetes mellitus, and celiac disease.
Some individuals with undetectable levels of serum IgA may have high titers of anti-IgA antibodies and are at risk for anaphylactic reactions to ...