Intratumor maturational heterogeneity within the murine myeloma MOPC-315

The murine myeloma MOPC-315 secretes a paraprotein which binds dinitrophenylated compounds. Maturational subsets which mimic normal B-cell differentiation were shown to exist within this monoclonal neoplasm. The maturational subsets were defined by an in vivo stem cell activity (plasmacytoma colony-forming unit-spleen), DNA synthesis ([3H]thymidine incorporation), membrane-bound paraprotein, and cells secreting the MOPC-315 paraprotein. Velocity sedimentation at unit gravity separated cells enriched for secreting the MOPC0-315 protein (14.6 mm/hr) from the plasmacytoma colony-forming unit-spleen enriched population (9.3 mm/hr). An in vivo sequential analysis of the appearance of tumor (i.v. challenge) in the spleen of BALB/c hosts did not reveal any discordant appearance of these same maturational subsets with respect to time. The MOPC-315 myeloma contains maturational subsets that mimic normal B-cell differentiation and apparently differentiates during a very early stage of its evolution within the host.