Preparation of a "chemical vaccine" against tumor progression.

A synthetic antigen containing the presumed receptor site for wheat-germ agglutinin (a lectin capable of specifically agglutinating tumor cells) elicits an immune response in mice capable of cross-reacting with receptor sites for wheat-germ agglutinin on tumor-cell surfaces. Mice immunized against the antigen in complete Freund's adjuvant are able to reject five times as many transplanted myeloma tumor cells as are rejected by otherwise identically treated control mice. Methylcholanthrene-induced tumors appear later in mice immunized against the antigen than in controls. The protection of mice against tumor transplants can be transferred to unimmunized mice with spleen cells, but not with serum from immunized donors. Immunization of mice against the wheat-germ agglutinin receptor seemed to have no marked deleterious effect on biological processes in normal dividing cells.