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Residual MHC Class II Expression on Mature Dendritic Cells and Activated B Cells in RFX5-Deficient Mice

1998; Cell Press; Volume: 8; Issue: 2 Linguagem: Inglês

10.1016/s1074-7613(00)80467-7

1097-4180

Björn E. Clausen, Jean‐Marc Waldburger, Frieder Schwenk, Emmanuèle Barras, Bernard Mach, Klaus Rajewsky, Irmgard Förster, Walter Reith,

T-cell and B-cell Immunology

Patients with major histocompatibility complex class II (MHC-II) deficiency are known to carry mutations in either the RFX complex or the trans-activator CIITA. While the pivotal role of CIITA for MHC-II gene transcription is supported by the essential absence of MHC-II molecules in CIITA-deficient mice, we demonstrate here that RFX5−/− mice retain expression of MHC-II in thymic medulla, mature dendritic cells, and activated B cells. Nevertheless, RFX5−/− mice develop a severe immunodeficiency due to the lack of MHC-II in thymic cortex, failure of positive selection of CD4+ T cells, and absence of MHC-II on resting B cells and resident or IFNγ-activated macrophages. This differential requirement for CIITA and RFX5 in subsets of antigen-presenting cells may be specific for the mouse; it may, however, also exist in humans without having been noticed so far.