The effect of an IgM plasmacytoma (TEPC-183) on the primary immune response of BALB/c mice.

Mice bearing plasmacytoma TEPC-183 IgM(k) have suppressed immune responses (IR) to both T-dependent and T-independent antigens, i.e. 2-4-dinitrophenyl (DNP) and the pneumococcal polysaccharides types I, III and XIV (SSS-I, SSS-III and SSS-XIV). Although these polysaccharides differ structurally and do not share antigenic determinants, the IR to all three is severely depressed. Antibody levels measured by radioimmunoassay to SSS-I and SSS-XIV were only 1/4 and to SSS-III 1/3 of the normal response. Antibody titres to DNP were 1/12 of those of normal mice. The number of direct PFC/spleen to DNP were reduced to 1/9 (817 vs 7747) and the indirect PFC to 1/16 (669 vs 10766) of the controls. In contrast, mice bearing S37 (a pleomorphic neoplasm) had antibody levels against SSS-I and SSS-III which were equal to or higher than the controls and only somewhat reduced to SSS-XIV. Anti-DNP antibody titres were reduced to half in S37 bearing mice compared to controls (299 vs 691) while the number of indirect PFC/spleen were comparable. The number of direct anti-DNP PFC/spleen was even higher in the S37 bearing mice than in the controls (4849 vs 2646). However, direct and indirect PFC/10 nucleated spleen cells were reduced in both TEPC-183 and S37 bearing mice, reflecting both splenomegaly and a reduction in the number of antibody secreting cells/10 spleen cells. Thus, TEPC-183 severely suppressed the IR to both the DNP-ligand and three pneumococcal polysaccharides, while the IR of mice bearing S37 was generally comparable or higher than the controls to both DNP and Pn-SSS. Possible mechanisms for the myeloma induced suppression are discussed.