CIITA or RFX coding region loss of function mutations occur rarely in diffuse large B-cell lymphoma cases and cell lines with low levels of major histocompatibility complex class II expression

CIITA or RFX coding region loss of function mutations occur rarely in diffuse large B-cell lymphoma cases and cell lines with low levels of major histocompatibility complex class II expressionLoss of major histocompatibility complex class II (MHCII) gene expression was associated with poor out-come in diffuse large B-cell lymphoma (DLBCL) in several studies.[1][2][3] The mechanism for lost expression is unknown.MHCII gene expression is controlled by several transcription factors, including RFX (composed of RFXB, RFX5, and RFXAP), CREB, and NF-Y.These transcription factors interact with a master transactivator protein class II transactivator (CIITA) to form an enhanceosome complex.4 In the Bare Lymphocyte Syndrome (BLS), MHCII gene expression is absent due to small deletions or point mutations in the coding or splicing regions of either CIITA or an RFX subunit.5 This study investigated whether DLBCL with low MHCII expression had mutations similar to BLS.DNA from 46 patient tumors, for which gene expression profiling was available, was obtained from the