CD4(-CELLS FROM MICE IMMUNIZED TO SYNGENEIC SARCOMAS RECOGNIZE DISTINCT, NON-SHARED TUMOR-ANTIGENS() T)

We have utilized a newly developed culture system to study the propert ies of antitumor CD4(+) T-cells relevant to the rejection of syngeneic methylcholanthrene sarcomas. Fresh syngeneic dendritic cells prepared from spleen, then pulsed with crude lysates of methylcholanthrene sar comas, evoke antigen-specific proliferation by CD4(+) but not by CD8() T-cells from tumor-immune mice. Unfractionated splenocytes display s imilar antigen presenting capacity if they are not irradiated before t he pulse with tumor lysate. CD4(+) T-cells from mice immunized to indi vidual methylcholanthrene sarcomas proliferate cross-reactively to den dritic cells pulsed with fresh tumor digests, but not to dendritic cel ls pulsed with cultured tumor cells. This apparent shared recognition of sarcoma lysates was demonstrated to be a result of sensitization to bacterial collagenase during the immunization procedure. Therefore, t he murine CD4(+) T-cell response to tumor immunization is similar to t he CD8(+) response in that sensitization occurs predominantly to tumor specific transplantation antigens rather than to shared tumor antigen s. Strategies to avoid artefactual tumor cross-recognition by CD4(+) T -cells are discussed.