Primary Immunodeficiencies

By completing this question set, you will be able to classify primary immunodeficiencies by the immune arm affected (B-cell, T-cell, combined, phagocyte, complement) and predict the infection pattern associated with each category. You will identify specific immunodeficiency syndromes from their characteristic clinical and laboratory features — tracing from the genetic defect through the disrupted immune mechanism to the resulting infection susceptibility. You will distinguish B-cell deficiencies (recurrent encapsulated bacterial infections) from T-cell deficiencies (viral, fungal, opportunistic infections), combined deficiencies (all pathogen types starting in infancy), phagocyte deficiencies (catalase-positive organisms, abscesses), and complement deficiencies (Neisseria, autoimmune disease). You will apply the diagnostic approach using immunoglobulin levels, lymphocyte subset analysis, respiratory burst testing, and complement function assays to confirm the suspected deficiency.