Abstract
An epithelial cell surface antigen is described which is defined by monoclonal antibody HEA125 (IgG1). The antibody was raised against the colon carcinoma cell line HT-29. Under reducing conditions HEA125 immunoprecipitates a surface glycoprotein of Mr 34,000 which was designated Egp34. The antigen does not contain disulfide-linked subunits. A slightly different migration behavior under non-reducing conditions (Mr 39,000) may be due to intrachain disulfide bonds. After enzymatic cleavage of N-linked carbohydrate residues the apparent molecular weight of the antigen was 29,000. Egp34 is a major cell surface component of HT-29 cells (10(6) molecules per cell). No antigen could be detected in the sera of colorectal cancer patients. A panel of malignant cell lines and normal cells was studied for surface expression of the antigen. 17/17 carcinoma lines of 6 different origins expressed the antigen, whereas 16/16 melanoma, neuroblastoma, sarcoma and lymphoma/leukaemia were unreactive as it was the case for normal fibroblasts and blood cells. Immunoperoxidase staining of frozen tissue sections with HEA125 demonstrated the presence of Egp34 in almost all normal epithelia and tumours derived therefrom. No reactivity with non-epithelial tissues was observed. Undifferentiated carcinomas of various origins homogeneously expressed Egp34. Therefore, HEA125 may become a valuable tool for the immunohistochemical diagnosis of carcinoma.
Highlights
In the present investigation we report on a monoclonal antibody that reacts with a cell surface antigen of Mr 34,000 present on all carcinoma cell lines tested, not on various cell lines and normal cells of non-epithelial origin
Monoclonal antibody HEA125 was selected out of 960 hybridoma cultures obtained in 4 fusions following immunization with the human colon carcinoma cell line HT29
Twenty-eight hybridomas that recognized each of the carcinoma lines HT-29, SK-LU-1 and HeLa but neither the melanoma line MML-I, nor the lymphoma lines Raji and JM-l were cloned by limiting dilution and further characterized
Summary
Received 24 February 1987; and in revised form, 10 July 1987. American Type Culture Collection (Rockville, MD): WiDr, SWI116, HeLa, T-24, Raji, Daudi, P3-HR1, HL-60, U-937 and K-562; from Drs J. Pfreundschuh (Memorial Sloan-Kettering Cancer Center, New York): HT29, SK-LU-1, SK-LC-LL, SK-MES-1, Calu-1, SK-N-SH, HEp-2, ME-180, AlAb, PSA and F136-35-36. Several other colleagues kindly donated their cell lines: ChaGo Heidelberg, FRG); LICR-LON-HMy-2 (Ludwig Institute of Cancer Research, UK)
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