Immunologic enhancement of allogeneic tumor growth with soluble histocompatibility-2 antigens.

Soluble, partially purified, histocompatibility antigens that were obtained from the membranes of A/J spleen cells have been assayed for their capacity to elicit immunologic enhancement of two tumors of A-strain origin: YAA-C1 and Sarcoma I. Crude membrane material and a partially purified, soluble antigen that were contained in a specific fraction, obtained after chromatography on a Sephadex G-150 column, elicited enhancement; this fraction has been shown to contain immunogenic histocompatibility-2(a) antigens as well as alloantigenic specificities that were detected serologically. Another soluble fraction did not induce enhancement; this fraction has been shown to contain antigens other than H-2. Passive enhancement of both tumors was achieved with antisera produced in allogeneic mice that were inoculated with crude membrane material or with a fraction obtained by Sephadex G-150 chromatography. These antisera contained cytotoxic and/or hemagglutinating antibodies. Immunologic enhancement was specific. A readily enhanceable tumor, Py 89, of C57BL origin was not enhanced with anti-H-2(a) antisera. These results suggest strongly that all important H-2(a) transplantation antigenic determinants of spleen cells can be recovered by partial papain digestion and fractionation on a Sephadex G-150 column.