Major histocompatibility complex class II deficiency: a clinical review

Blood Rev. 1996 Dec;10(4):242-8. doi: 10.1016/s0268-960x(96)90008-9.


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.

Publication types

  • Review

MeSH terms

  • Female
  • Genes, MHC Class II
  • Histocompatibility Antigens Class II / metabolism*
  • Humans
  • Immunologic Deficiency Syndromes / genetics*
  • Immunologic Deficiency Syndromes / immunology*
  • Immunologic Deficiency Syndromes / metabolism
  • Infant
  • Male


  • Histocompatibility Antigens Class II