Development of sensitive and specific microassays of direct and indirect migration inhibition was conducted. These assays were used in guinea pig hepatocarcinoma and mouse mammary tumor virus-induced tumor models to measure reactivity against tumor-associated antigens and to monitor immunotherapy with BCG. The microassay appeared to detect a cross-reactive antigen between BCG and the guinea pig hepatocarcinoma. Microassays were used to longitudinally monitor reactivity against tumor antigens or BCG in guinea pigs bearing hepatocarcinomas and treated with BCG or mice bearing mammary tumors in attempts to see if they could be used as predicators of tumor recurrence or survival. Conventional direct capillary tube migration inhibition tests were used to measure reactivity of human breast and lung cancer, melanoma and Ewing's sarcoma patients against extracts prepared from fresh and tumor cell lines derived from these tumors. Indirect assays demonstrated interaction of patient's cells and tumor antigen cause the release of the lymphokine, leukocyte inhibitory factor. Studies were performed with indirect migration inhibition with supernatants containing leukocyte inhibitory factor. BIBLIOGRAPHIC REFERENCES: McCoy, J.L., Dean, J.H., Cannon, G.B., Maurer, B.A., Oldham, R.K. and Herberman, R.B.: Detection of cell-mediated immunity against tumor-associated antigens of human breast carcinoma by migration inhibition and lymphocyte-stimulated assays. In Wybran, J., and Staquet, M. (Eds.): Clinical Tumor Immunology. Oxford, Pergamon Press, 1976, pp. 77-86. Dean, J.H., McCoy, J.L., Cannon, G.B., Leonard, C.M., Perlin, E., Kreutner, A., Oldham, R.K. and Herberman, R.B.: Cell-mediated immune response of breast cancer patients to autologous tumor-associated antigens. J. Natl. Cancer Inst. 58: 549-555, 1977.