A renal cell carcinoma neoplastic antigen detectable by immunohistochemistry is defined by a murine monoclonal antibody

BALB/c mice were hyperimmunized with ACHN (ATCC CRL 1611, American Type Culture Collection, Rockville, Maryland), a stable in vitro cell line derived from a malignant pleural effusion in a 22‐year‐old man with renal cell carcinoma. The hyperimmune spleen cells were fused with NS‐1 murine myeloma cells using polyethylene glycol. Hybridoma supernatants were screened for the presence of IgG reactive with detergent extracts of ACHN and nonreactive with detergent extracts of normal kidney tissue. A stable, rapidly growing clone named 5F4 was isolated. Supernatant from 5F4 was used as a primary antibody preparation for avidin‐biotin complex immunoperoxidase staining of multiple cases of renal cell carcinoma, normal tissues, and other tumors. 5F4 produced IgG which reacted with a cytoplasmic structure in paraffin‐embedded sections of all renal cell carcinomas tested. There was occasional, weak, granular, cytoplasmic staining of isolated tubular lining cells in adjacent normal kidney.