Primary immunodeficiency due to a defect in adaptive immunity

Primary immunodeficiency due to a defect in adaptive immunity is a broad category of inherited immune system disorders (Orphanet code 179006) in which the body's adaptive immune system — comprising T lymphocytes, B lymphocytes, or both — fails to function properly. This group encompasses a wide range of specific conditions, including severe combined immunodeficiencies (SCID), combined immunodeficiencies, predominantly antibody deficiencies, and other disorders where the specialized, antigen-specific arm of the immune response is impaired. Because adaptive immunity is essential for targeted defense against infections and for immunological memory, patients with these conditions are highly susceptible to recurrent, severe, and often unusual infections caused by bacteria, viruses, fungi, and opportunistic organisms. The clinical presentation varies depending on the specific underlying defect but commonly includes recurrent sinopulmonary infections, chronic diarrhea, failure to thrive in infants and children, skin infections, and susceptibility to opportunistic pathogens. Some patients may also develop autoimmune manifestations, lymphoproliferation, or an increased risk of malignancy. The severity ranges from life-threatening conditions presenting in the neonatal period (such as SCID) to milder antibody deficiencies that may not be diagnosed until adulthood. Treatment depends on the specific diagnosis and severity. Immunoglobulin replacement therapy is a cornerstone for antibody deficiencies. Prophylactic antimicrobials are frequently used to prevent infections. For severe forms, particularly SCID and certain combined immunodeficiencies, hematopoietic stem cell transplantation (HSCT) is the definitive curative treatment. Gene therapy has emerged as a therapeutic option for select conditions. Supportive care, infection surveillance, and avoidance of live vaccines are important management strategies across this disease group.

Common questions about Primary immunodeficiency due to a defect in adaptive immunity