LACK OF IL-1 SECRETION FROM HUMAN MYELOMA CELLS HIGHLY PURIFIED BY IMMUNOMAGNETIC SEPARATION

This paper describes a method for purification of human myeloma cells. Mononuclear cells from six bone marrow samples and one pleural fluid sample from multiple myeloma patients were incubated with B-B4, a mono clonal antibody that is specific for plasma cells, and the B-B4+ cells were isolated using monosized magnetic beads coated with sheep anti-m ouse Ig. With this positive selection method it was possible to achiev e primary cultures with more than 99% myeloma cells. The average viabi lity of these cultures was 81%. The B-B4 antibody did not alter prolif eration or cytokine production of the myeloma cell lines U-266 and JJN -3. The B-B4+ myeloma cultures did not produce IL-1 and made only smal l amounts of IL-6 (< 93 pg/ml), whereas the cells remaining after extr action of the B-B4+ cells produced IL-1 (89-350 pg/ml) and large amoun ts of IL-6 (520-17000 pg/ml). This indicates that the B-B4+ myeloma ce lls are not directly responsible for the overproduction of these cytok ines in multiple myeloma. This separation technique gave higher purity of myeloma cells than has been previously reported for any negative s election method and is recommended when high culture purity is of crit ical interest.