MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-II DEFICIENCY - CLINICAL MANIFESTATIONS, IMMUNOLOGICAL FEATURES, AND OUTCOME

Major histocompatibility complex class II deficiency (bare lymphocyte syndrome) is a rare primary immunodeficiency disorder characterized by profound defects in human leukocyte antigen class II expression, inco nsistent and incomplete expression of human leukocyte antigen class I molecules, and a complete lack of cellular and humoral immune response s to foreign antigens. To define the clinical and immunologic characte ristics, outcome, and natural history of major histocompatibility comp lex class II deficiency, we retrospectively analyzed 30 consecutive pa tients. Clinical onset occurred in the first year of life, usually inv olving recurrent bronchopulmonary infections and chronic diarrhea. The clinical course was complicated by viral meningoencephalitis, hepatit is, cholangitis, and various autoimmune phenomena. Prognosis was very poor: the mean age at the time of death was 4 years. The main cause of death was overwhelming viral infection. Recent advances in bone marro w transplantation have raised hopes of curative treatment: 6 of 14 pat ients who underwent bone marrow transplantation were cured. Long-term survival after human leukocyte antigen-identical and haploidentical bo ne marrow transplantation seemed to depend primarily on the presence o f preexisting viral infections.