 Altogether, this complex contributes to maintain MHC-II loaded vesicles within the immature dendritic cell, impeding its translocation to the cell membrane.One type of MHC class II deficiency, also called bare lymphocyte syndrome, is due to mutations in the genes that code for transcription factors that regulate the expression of the MHC class II genes.It results in the depletion of CD4 T cells and some immunoglobulin isotypes even though there are normal levels of both CD8 Cells and B cells present.