Immunodeficiency Lab. diagnosis

2. Introduction

3. Lab. screening for children with PID
White blood cell counts
Erythrocyte sedimentation rate
Serum IgG, IgM and IgA
Isohemagglutinin titers
Shick test
Delayed cutaneous hypersensitivity tests
Hemolytic complement (CH50)

4. Screeningevaluation
• CBC with differential
• Quantitative immunoglobulins
o (IgG, IgA, IgM, IgE)
• Baseline and post-immunization titers
o Protein and polysaccharide antigens (i.e.,
Pneumococcal, Diphtheria)
• CH50/AH50
IgG
Age 0-1 years: 231-1411 mg/dL
Age 1-3 years: 453-916 mg/dL
Age 4-6 years: 504-1464 mg/dL
IgA
Age 0-1 years: 0-83 mg/dL
Age 1-3 years: 20-100 mg/dL
Age 4-6 years: 27-195 mg/dL
IgM
Age 0-1 years: 0-145 mg/dL
Age 1-3 years: 19-146 mg/dL
Age 4-6 years: 24-210 mg/dL
 Tetanus and diphtheria are protein-
based vaccines
 pneumococcus is polysaccharide-based
vaccines
 If any serum vaccination titers are below
normal, revaccination and assessment
of titers 4–6 weeks later.
 Patients with C1, C2, or C4
deficiency will have a low CH50
 Patients with a low AH50, but
normal CH50, suggest a deficiency
of factor B, factor D, or properdin

5. Advancedtesting
• B-cell maturation assessment by flow cytometry
• Assessment of other immunizations
• B-cell signaling assays
• TREC/KREC analysis
• Advanced flow cytometry studies
• Genetic mutational analysis
If initial screening of quantitative antibody levels or specific antibody production yields concerning
results, additional testing can be done

6. Screening • CBC with differential
• Immunophenotyping
o T-, B-, NK-cell counts and CD45RA/RO+
status
Advanced • Functional testing
o DTH testing
• TREC assay
• Genetic evaluation
• Advanced flow studies
o i.e., TH17, CD40L, WASp, etc.
ImmunophenotypingisbetterthanCBC,as
thepatternofmissingcelltypeshelpsto
delineatetheimmunologicdefectpresent
 Purified protein derivative (PPD), Candida
albicans,Mumps
 Intradermal / evaluated 48–72 h later /
cutaneous induration greater than 2 mm
 LIMITATION: previous exposure /less than
12 months / falsely negative / falsely positive
 TREC T-cell receptor excision circles
 TRECs are circular, non-replicating
pieces of DNA which are excised during
T-cell receptor rearrangement
 typically prior to the individual’s first
infection