Immunospecific Regression of Various Syngeneic Mouse Tumors in Response to Neuraminidase-Treated Tumor Cells

Summary

Firmly established tumors in syngeneic mice regressed if the host was challenged with living tumor cells that were exposed to Vibrio cholerae neuraminidase (VCN) in vitro. The effect was immunospecific and could be induced only with VCN-treated tumor cells identical with the growing tumor. Although these Findings were initially discovered in methylcholanthrene-induced fibrosarcomas, we extended them to C3HBA strain of transplantable mammary adenocarcinomas in C3H/HeJ mice, 2 transplantable C3H/HeJ mammary adenocarcinomas that arose spontaneously (M-1, M-2), and B16 melanoma in C57BL/6J mice. Regression could not be induced in Sal or C1300 tumors in A/J mice. VCN-treated M-1 tumors could not induce the regression of M-2 tumors (or vice versa) in virus-infected C3H/HeJ mice. Thus VCN-treated cells possessing virus-associated antigens could not break the immunologic unresponsiveness of the virus-infected mouse. VCN-treated M-1 (or M-2) tumor cells induced the regression of M-1 (or M-2) tumors. Thus VCN altered the immunogenicity of the “private” tumor-specific antigens on these tumors. The origin of the tumor, strain of mouse, and characteristics of the tumor antigens may have an effect on the determination of responsiveness to specific immunotherapy.