Primary immunodeficiency is a defective immune response resulting from an inherited or acquired gene defect, distinct from secondary immunodeficiency caused by external agents. This concept belongs to immunology, and its theoretical framework categorizes deficiencies by which cellular component of the immune system is affected (B-cells, combined T- and B-cells, phagocytic cells, or T-cells alone), with each category producing a characteristic pattern of susceptibility to opportunistic infection: T-cell defects predispose to intracellular pathogens, while defects in B-cells, phagocytes, and complement predispose to extracellular bacterial infection. Inheritance patterns (autosomal recessive, autosomal dominant, X-linked) and the relative rarity but high explanatory value of these disorders illustrate how single-gene defects can be used to dissect the function of individual components of the broader immune response.
Primary immunodeficiency is a defective immune response resulting from an inherited or acquired gene defect, distinct from secondary immunodeficiency caused by external agents. This concept belongs t…