Cell-mediated immunity against particulate and solubilized tumor-associated antigens of murine plasmacytomas detected by macrophage migration inhibition assays.

Cell-mediated immunity (CMI), as detected by the agarose microdroplet macrophage migration inhibition (MMI) assay, was investigated using peritoneal exudate cells (PEC) of BALB/c mice and several crude membrane (CM) and solubilized preparations of murine plasmacytomas. The MMI assay was quite sensitive and detected inhibition of macrophage migration as low as picogram quantities of CM, NP40 detergent- and papainsolubilized preparations (CS) of ADJ-PC5 and LPC-1 plasmacytomas. The data were highly reproducible from one experiment to the next with the same or different lots of the CM or solubilized extracts. Specificity studies demonstrated that ADJ-PC5 and LPC-1 plasmacytomas expressed cross-reactive tumor-associated antigens (TAA) as detected by MMI and confirmed by tumor challenge and Winn neutralization experiments. No cross-reactivity was observed with similar extracts prepared from an unrelated syngeneic simian virus 40 (SV40)-induced sarcoma. The inhibition of macrophage migration observed was mediated by culture supernatants generated from the mixture of plasmacytoma-immune spleen cells with antigens and then assayed in an indirect MMI assay on normal PEC. The agarose microdroplet MMI assay appeared to be a rapid and sensitive method to measure TAA recognition and to monitor TAA isolation and solubilization with minimum numbers of immune cells.