Primary immunologic deficiency diseases are estimated to affect 1 in 4000 individuals; most are genetically determined and present in early childhood. Nonetheless, several important immunodeficiency disorders present in adulthood, most notably the antibody deficiency syndromes: selective IgA deficiency, common variable immunodeficiency (CVID), and specific (functional) antibody deficiency (Table 20–14). Antibody deficiency predisposes patients to recurrent serious bacterial 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, which results in infections with different spectra of organisms depending on the severity of the immune defect.
Table 20–14.Selected primary immunodeficiency syndromes. ||Download (.pdf) Table 20–14. Selected primary immunodeficiency syndromes.
|Disease ||Clinical Presentation ||Diagnosis1 ||Treatment |
|Complement disorders || |
“Early” complement component (C1–C4) 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. Genetic testing if complement level absent. ||Prompt administration of antibiotics and Neisseria vaccination if C5–C8 deficient. Immune suppression if C1–4 deficient to treat organ specific autoimmunity. |
|Good syndrome ||Current or past thymoma, recurrent severe sinopulmonary infections, may also have opportunistic infections. ||Hypogammaglobulinemia (IgG, IgM, IgA), absent B cells on flow cytometry, may present with pure red cell aplasia or cytopenias. Chest film consistent with thymoma. ||IgG-RT (subcutaneously or intravenously) 300 mg–500 mg/kg/month |
|Hereditary angioedema ||Unpredictable swelling of face, lips, tongue, hands, feet; no urticaria; GI tract swelling causing severe abdominal pain ||Decreased C1 esterase inhibitor serum level and/or function, decreased serum C4 level. || |
Prophylactic treatment: Danazol, tranexamic acid
Acute treatment: C1 esterase inhibitor product, kallikrein inhibitor, bradykinin receptor antagonist
|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 confirming defective oxidative burst. Genetic testing confirming diagnosis.
|Antimicrobial prophylaxis; interferon for 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 (Table 20–14); its prevalence is about 1 in 500 individuals, with a higher prevalence in White persons. Most affected individuals are asymptomatic. A minority of patients have recurrent bacterial infections such as sinusitis, otitis, bronchitis, and GI infections. Selective IgA deficiency can be associated with an increased incidence of atopic and autoimmune disorders, including Graves disease, SLE, juvenile rheumatoid arthritis, type 1 diabetes mellitus, and celiac disease.