B-cell differentiation antigen expressed on a human myeloma cell line (KMM-1)

KMM-1 is a human multiple myeloma cell line previously shown to express plasma cell phenotypes. Hybridomas against this cell line were produced by fusing spleen cells from hyperimmunized BALB/c mice with X63-Ag8-653 mouse myeloma cells. One monoclonal antibody derived from this fusion, termed 33-3, reacted with all the B-cell stages except the pre-B-cell stage. Both myeloma cells from patients and those from KMM-1 cells were reactive at the same maximum dilution of this antibody. No reactivity was seen with cells of T-lymphocyte origin, platelets, red blood cells, monocytes or granulocytes. The 33-3 antibody was unable to detect any specific marker distinguishing cultured myeloma cells from those that could not be cultured in vitro.