Two distinct human myeloma cell lines originating from one patient with myeloma.

Two distinct cell lines (OPM-1 and OPM-2) were established from the peripheral blood of a 56-year-old female myeloma patient at the stage of terminal leukemic evolution associated with loss of cytoplasmic immunoglobulin heavy chain (G lambda----lambda). The lines grew in suspension with a doubling time of 36-42 hr and 30-36 hr, respectively. EBNA was absent from both lines. The lines synthesized cytoplasmic lambda-chain, but had no detectable surface immunoglobulins. Fc receptors and complement receptors could not be detected in either line. The lines had very complex chromosomal abnormalities, but the patterns of chromosomes differed greatly between the two lines. The two lines, together with the RPMI 8226 line established by Matsuoka et al. (1967), were analyzed for phenotypic expression as defined by a panel of monoclonal antibodies to B cells (B1, BA-1, BA-2, BA-3, OKIa-1 and OKT10/BMA0100). Neither OPM-1 nor OPM-2 reacted with any of the antibodies tested except OKT10. OPM-1 cells reacted weakly (less than 30%) with OKT10/BMA0100, while OPM-2 cells showed a fluctuating reactivity, ranging from 40 to 80%, with OKT10/BMA0100. In contrast, RPMI 8226 reacted strongly with OKT10 and BA-2. These results demonstrate the presence of phenotypic heterogeneity in all 3 myeloma cell lines, suggesting that the lines might represent different stages of terminal B-cell development.