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Table 4 Investigation of PID

From: Spectrum of primary immunodeficiency disorders in Sri Lanka

PID Clinical features Suggested investigation
Combined (T and B cell deficiency) Failure to thrive, severe viral, intracellular bacterial (atypical, extrathoracic or disseminated tuberculosis, disseminated infections with poorly pathogenic mycobacteria), fungal (persistent mucocutaneous candidiasis, invasive aspergillus or mucor), protozoal (cryptococcus meningitis, chronic diarrhea due to giardia) infections Interstitial pneumonitis due to P.jiroveci, lymphopenia in infancy (< 2,500/μl) Full blood count and differential
Lymphocyte subsets by flowcytometry (CD3, CD 4, CD 8, CD 16 and CD 56, CD 19)
Serum immunoglobulin levels (IgG, IgA, IgM, IgE)
T cell proliferation assay
Delayed type hypersensitivity test (using purified protein derivative, mumps, tetanus vaccines).
Further tests may be necessary
Antibody deficiency Recurrent/severe sinopulmonary infections, arthritis, meningitis, osteomyelitis, infections with capsulate bacteria, chronic diarrhea or malabsorption. Viral infection (meningoencephalitis with entero viruses) Serum immunoglobulin levels (IgG, IgA, IgM, IgE)
Lymphocyte subsets (including CD 19). Functional antibodies (isohemagglutinins *, anti tetanus/anti diphtheria IgG, anti pneumococcal/anti typhoid Vi IgG**)
Further tests may be necessary
Other well defined immune deficiencies Ataxia and telangiectasia (ataxia telangiectasia), cardiac defects, hypocalcemia, hypoplastic thymus and dysmorphic facial features (chromosomal 22q.11.2 deletion), eczema in infancy, recurrent skin abscesses, pneumonia with pneumatoceles and dysmorphic facies (hyper IgE syndrome) Tests depend on disease
Phagocytic defects Recurrent skin abscesses or cellulitis, visceral abscesses, mucocutaneous ulceration, granuloma formation, invasive fungal infection, Full blood count and differential. If neutropenia, identify cause. If neutrophil count normal, depending on clinical features tests for chronic granulomatous disease (nitro blue tetrazolium assay, dihydro rhodamine assay) or leukocyte adhesion defect type 1 (CD18, CD 11 a, CD 11b, CD 11c by flowcytometry) and type 2 (CD 15 by flowcytometry)
Disseminated mycobacterial disease, BCGosis, disseminated non typhoid salmonellosis (MSMD) Tests in specialized laboratories
Complement defects Infections with encapsulated bacteria, recurrent meningococcal infections, lupus like vasculitis Functional hemolytic complement assays (CH 50 and AP 50)
If abnormal, is followed by evaluation of individual complement components
  1. *After one year of age.
  2. **After 2 years of age.