title: Major histocompatibility complex class II deficiency: a clinical review.
abstract: Major histocompatibility complex Class II deficiency or bare lymphocyte syndrome is a rare combined immunodeficiency that accounts for 5% of all cases of severe combined immunodeficiency. The syndrome is characterized by a lack of human leucocyte antigen Class II gene expression, absence of cellular and humoral T-cell immune response to foreign antigens, and impaired antibody productions, resulting in extreme susceptibility to viral, bacterial and fungal infections. In some patients, there is a reduced cell surface expression of human leucocyte antigen Class I molecules also. Major histocompatibility complex Class II deficiency is an autosomal recessive disease, most frequent in the Mediterranean area. The disease is caused by impaired gene regulation involving trans-acting proteins. Somatic cell genetics using cell fusion experiments identified four complementation groups, all resulting in the same clinical manifestation. Two regulatory genes have been identified so far: Class II trans activator and regulatory factor X5. Supportive treatment includes intravenous gammaglobulin and prophylaxis against Pneumocystis carinii. The only curative treatment is bone-marrow transplantation.
authors.affiliation: Department of Pediatrics and Pediatric Hematology, Rambam Medical Center, Haifa, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Elhasid
authors.forename: A
authors.initials: A
authors.lastname: Etzioni
mesh_terms: D005260:Female; D005802:Genes, MHC Class II; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D007223:Infant; D008297:Male
chemical_list: D000949:Histocompatibility Antigens Class II