In this application we propose to prepare a series of hybrid cell lines that produce monoclonal human antibodies against cell surface antigens of human melanoma cells. These hybrids will be prepared by the fusion of myeloma cells with the lymphocytes of melanoma patients who are undergoing an active immune response to their tumor cells. Culture fluids from the hybrid cells will be tested for serological activity against melanoma cells. For the initial screening procedure we have established a series of matched cell lines (melanoma cells, skin fibroblasts, and B cells) from eleven individual melanoma patients. Hybrid cells which produce antibodies that react selectively with the melanoma cells in vitro will be cloned and used as the source of homogeneous immunoglobulin. Subsequently, these monoclonal anti-melanoma antibodies will be examined further for specificity by immunofluorescence and immunoperoxidase tests with biopsied tissues that will be obtained from melanoma patients. In these biopsied samples we will be able to compare the reactions of the anti-melanoma antibodies with both tumorous tissues and the normal cell counterparts that reside in adjacent segments of the tissue.