General Approach to Primary Immunodeficiency (PID) in Adults

Abstract

Primary immunodeficiencies are a group of inherited disorders of the immune system function that predispose affected individuals to an increased frequency and severity of infection, abnormal inflammatory responses, autoimmune disease, and malignancy. Secondary causes of immunodeficiency must be ruled out before diagnosing primary immunodeficiency. There are 10 warning signs of primary immunodeficiency that have been proposed by the “Jeffrey Modell Foundation” for children and for adults. Primary immunodeficiencies are classified based on “International Union of Immunological Societies” into many types: Immunodeficiencies affecting cellular and humoral immunity; combined immunodeficiencies with associated or syndromic features; predominantly antibody deficiencies, diseases of immune dysregulation; congenital defects of phagocyte number, function, or both; intrinsic and innate Immunity defects; autoinflammatory disorders; complement deficiencies; and phenocopies of primary immunodeficiency. Clinical manifestations include recurrent infection history, autoimmune diseases, atopy, and malignancy, among others. Common pathogens/infection sites depend on the underlying immune defect. Causes of secondary immunodeficiency include immunosuppressive treatments, malignancy, and splenectomy, among others. Diagnostic investigations generally include a complete blood count with differential, quantitative immunoglobulins, lymphocyte immunophenotyping, complement levels, and other tests. Management depends on the type of immunodeficiency, and it may involve immunoglobulin replacement therapy, infection prophylaxis, and patient monitoring for associated conditions/complications, as well as other management strategies.