A monoclonal antibody to human transitional-cell carcinoma of the bladder cross-reacting with a differentiation antigen of neutrophilic lineage.

A monoclonal antibody (MAb) to human transitional-cell carcinoma of the bladder (TCCB) was obtained by immunization of a BALB/c mouse with formalin-fixed TCCB cells and subsequent fusion of the spleen cells with SP2-OAg14 myeloma line. GF 26.7.3 MAb was selected by indirect immunofluorescence (IIF) as reacting agent with target cells and negative with autologous lymphocytes and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell-line. GF 26.7.3 reacts with a high percentage of bladder and colon carcinomas when examined by IIF and immunoperoxidase techniques and cross-reacts with a determinant expressed on neutrophilic cell lineage. The IIF analysis performed on bone marrow and peripheral blood (PB) from healthy subjects and leukemic patients and on leukemic cell lines showed that the expression of the structure detected by GF 26.7.3 is restricted to the neutrophilic cell lineage and first expressed at the promyelocytic level. Immunoprecipitation and SDS-polyacrylamide gel electrophoresis (PAGE) of 125 I-labelled membrane proteins from target cells were performed, but no bands were detected by autoradiography. In addition, pronase insensitivity and periodate sensitivity suggest the possible involvement of a carbohydrate determinant.