Relationship of tumor-specific transplantation antigens to the histocompatibility complex: dissociation of in vitro alloantigen expression and in vivo alloimmunity from tumor-specific transplantation antigen strength.

The studies reported here explore the relationship between tumor-specific transplantation antigens (TSTA) and (1) the expression of serologically defined specificities, and (2) the immunogenicity of H-2K- or H-2D-determined alloantigens on methylcholanthrene (MCA)-induced murine fibrosarcomas. Expression of H-2K and H-2D serologically-detected private specificities on groups of tumors raised in B10.A, B10.BR or B10.D2 strains varied greatly among tumors. No regular reciprocal or direct relationship to tumor TSTA strength was found. Each tumor, however, expressed H-2K or H-2D alloantigens stably as determined by direct cytotoxicity or absorption techniques. Even those tumors expressing little or no detectable alloantigen by serologic analysis were immunogenic in H-2K or H-2D incompatible congeneic hosts. This was assayed in terms of capacity to evoke primary or secondary tumor resistance, and to induce allo-antibody toward private H-2K or H-2D end specificities. An exception was that B10.BR tumors failed to induce anti-H-2Dk antibody despite strong surface alloantigen expression. While TSTA strength did not correlate with serologically detected alloantigen expression, TSTA strength did tend to correlate inversely with capacity to resist primary growth in the H-2K different host, and directly with resistance in the H-2D different host.