Thus, when HLA-DRB1*04:01-expressing CLL cells are exposed to a mouse κLC-containing anti-human IgM F(ab’)2 antibody (Ms κ+ anti-IgM), CLL cells can internalize and process the mouse antibody and then present the κLC-derived peptide to SKW3-T18 cells. This evidence concerns the gene HLA-DRB1 and B-cell chronic lymphocytic leukemia.