Monoclonal Antibodies to Human Urothelial Cell Lines and Hybrids: Production and Characterization

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Abstract
Independent monoclonal antibodies, (11) the LBS series, were isolated after immunization of mice with RT112 cells, a continuous cell line derived from a transitional cell carcinoma of the human bladder. These antibodies were tested by indirect immunofluorescence on a panel of 28 human cell lines, of which 17 were urothelial carcinoma-derived, 4 of nonurothelial carcinoma origin, 3 fibroblast cell lines, 4 lymphoblastoid lines and 7 murine cell lines. Also tested were 7 somatic cell hybrid clones derived by fusion of human RT112 cells with murine bladder carcinoma MB63T/H cells. None of the LBS antibodies reacted with mesenchyme-derived cells, although all reacted with RT112 cells. On the basis of reactivity with the cell line panel, the antibodies were divided into 3 groups. Group I (LBS-1 and 19) reacted with all human epithelium-derived cell lines. Group II (LBS-2, 8,15 and 17) reacted only with human urothelium-derived cells, tending to recognise the least anaplastic types. Group III antibodies (LBS-10, 20A, 20B, 21 and 34)were urothelium-specific on the human continuous cell line panel, but additionally reacted with murine urothelial and epithelial cell lines. The 6 human-specific antibodies (group I and II) were used for preliminary analysis of human gene expression in a series of 7 mouse .times. human urothelial somatic cell hybrids. Each hybrid reacted with at least 1 LBS antibody, although there were changes in gene expression with time in culture, indicating both loss and unmasking of human genes. Apparently, the LBS-series antibodies recognize different determinants associated with epithelial and urothelial cell differentiation, and thus may be valuable probes in the study of normal differentiation and malignant transformation in human urothelial cells.