The overall objective of this project is to study in detail human tumor-specific immunity directed against melanomas, sarcomas and carcinomas, to correlate this with the clinical status of the patient's disease, and to define cellular variations in the expression of tumor- specific antigens. During the year 1973-74 the following will be investigated: 1. Further studies will be carried out on the specificity of tumor reactive antibodies in the sera of patients with melanoma using fluorescent antibody methods. More sera will be titered and compared to non-melanoma cancer patients' sera. Their reactivity with fetal antigens will be investigated by absorbing them with fetal tissues and then testing them against tumor cells. The unabsorbed sera also will be tested against fetal tissues. 2. Melanoma sera will be screened for cytotoxic antibodies using the trypan blue dye exclusion method. 3. Attempts will be made to determine whether sera from melanoma patients contain antibody-antigen complexes by separating out the immunoglobulins, treating them with low pH glycine buffer, followed by column chromatography or ultrafiltration to separate out complexes. 4. Studies on cell-mediated immunity to melanomas will be continued using the 99mTc microcytotoxicity assay. Data obtained by the visual enumeration of surviving cells will be compared to that obtained by gamma counting for 99mTc. Attempts will be to correlate this reactivity with the clinical status of disease. 5. The 99mTc microcytotoxicity assay will be further evaluated by employing it in studies of tumor- specific immunity in murine model systems with mythylcholanthrene induced sarcomas and the B16 melanoma.