Alien Histocompatibility Determinants on the Cell Surface of Sarcomas Induced by Methylcholanthrene. II. in Vitro Serological Studies

Abstract

In vitro serological studies were carried out in an attempt to identify the foreign histocompatibility antigens previously detected by transplantation methods on the cell surface of 2 methylcholanthrene-induced BALB/c fibrosarcomas (TZ15 and ST2). The reactivity of the anti-TZ15 and anti-ST2 syngeneic sera and of the C57BL/6J anti-TZ15 and anti-ST2 sera (the latters preabsorbed on normal BALB/c lymphoid cells) was evaluated on normal lymph node cells of C3Hf, C57BL/6J, DBA/2 and AKR strains by the complement-dependent cytotoxicity and on normal fibroblasts of C3Hf and C57BL/6J mice by the isotopic antiglobulin assay. The ability of in vitro-plated TZ15 and ST2 cells to bind BALB/c anti-C3Hf, anti-C57BL/6J, anti-AKR and anti-DBA/2 alloantisera was also examined by the antiglobulin assay. Contrary to the in vivo data, no cross-reactions were found between TZ15 and AKR normal cells, since both syngeneic and allogeneic anti-TZ15 sera were not cytotoxic to C3Hf, C57BL/6J or AKR lymphoid cells nor could BALB/c anti-C3Hf, anti-C57BL/6J or anti-AKR sera bind to TZ15 tumor cells in the antiglobulin assay. Both BALB/c anti-ST2 and C57BL/6J anti-ST2 sera were also ineffective in killing normal C3Hf, C57BL/6J, AKR and DBA/2 lymphoid cells in the complement–dependent cytotoxic assay, whereas a weak but significant binding of the syngeneic anti-ST2 serum to C57BL/6J but not to C3Hf fibroblasts was detected by the antiglobulin test. ST2 but not TZ15 cells were also able to significantly absorb the complement–dependent cytotoxic activity of a BALB/c anti-C57BL/6J but not of a BALB/c anti-C3Hf antiserum. In addition, BALB/c anti-C3Hf, anti-C57BL/6J and anti-AKR sera but not BALB/c anti-DBA/2 serum strongly bound to ST2 cells in the antiglobulin test; this binding activity was absorbed by C3Hf, C57BL/6J, AKR, and NIH but not BALB/c and DBA/2 lymphoid cells. Thus, among the cross-reactions observed in vivo between ST2 and normal cells of C3Hf, DBA/2 and C57BL/6J strains, only C57BL/6J normal antigens were detectable by serology. A new but still undefined system of alien normal antigens shared by C3Hf, AKR, C57BL/6J, NIH lymphoid and ST2 cells was revealed by the BALB/c alloantisera in the antiglobulin assay. The relationship of these findings with those previously obtained in the transplantation study with the same tumors is discussed.