Immunochemical behaviour of a tumour-associated antigen obtained from an AKR mouse lymphoma.

A soluble tumour-associated antigen was prepared by homogenizing AKR lymphoma cells (L15) followed by treatment with acetone and glycine-HCl buffer pH 3. It was analyzed by immunoelectrophoresis, rocket electrophoresis in the presence of Concanavalin A and SDS-PAGE. It showed rapid electrophoretic mobility, and the major component had an estimated molecular weight of 70,000 daltons. The molecular composition of the antigen included a glycoprotein. Specific antibodies against this antigen were demonstrated in BALB/c mice in which the AKR lymphoma was conditioned to grow by introducing the L15 cells into a subcutaneously implanted glass cylinder. In this model antibodies were found in both tumour-bearing (progressor) and tumour-rejecting (regressor) animals. In vivo experiments showed that pretreatment of BALB/c mice with L15 acellular extracts, 10 days before tumour challenge, led to a significant increase in allogeneic tumour growth. A rabbit anti-tumour extract serum was prepared and was rendered tumour -specific by exhaustive absorption with normal AKR serum and tissues. It shared the same epitopic specificity with tumour progressor or regressor mouse sera since indirect immunofluorescence using L15 cells could be reciprocally inhibited.