The bare lymphocyte syndrome: molecular clues to the transcriptional regulation of major histocompatibility complex class II genes

The bare lymphocyte syndrome (BLS), a rare severe combined immunodeficiency that is autosomal recessive, is discussed in relation to molecular clues about major histocompatibility complex (MHC) class II genes and their transcriptional regulation. Complementation group A cells have defects in the class II transactivator (CIITA), deficiencies in the complementation groups B,C, and E exist, and CIITA and the regulatory-factor X (RFX) complex are integral parts of MHC class II expression.