A study of the immune response to the organ-specific neoantigen of human bladder cancer.

The antitumor immune response of monocytes armed with cytophilic antitumor antibody to an organ-specific neoantigen of human bladder cancer was measured by the tube leukocyte adherence inhibition assay. Of 29 patients with Stage A bladder cancer, 27 had positive tests, whereas of 11 patients with Stage B, C and D bladder cancer, 2 had positive tests. If the leukocytes from advanced bladder cancer patients were preincubated briefly with prostaglandin E2, the negative response was converted to positive. Of 189 patients with diseases of other organs, 2 had positive tests. Patients with acute or chronic cystitis had negative tests. The sensitivity of the assay was 88 per cent; specificity was 95 per cent. The bladder cancer extracts prepared from metastatic tissue or the tissue-cultured cell line, T24, had similar activity in the assay. Normal bladder tissue did not share the bladder cancer organ-specific neoantigen nor did cancers of other organs. Bladder epithelial cells expressed the OSN before they acquired invasive properties since patients with dysplastic bladder epithelium or in-situ cancer had positive tests. Antitumor immunity was often detectable before a recurrence became obvious by cystoscopy or cytology of urine and became undetectable quickly after removal of the bladder cancer. Of 100 patients with prior bladder cancer without evidence of exophytic tumor, 18 had positive tests; the possibility must be considered seriously that some had precancerous changes which formed no visible gross abnormalities. The results suggested that antitumor immunity to bladder cancer was a sensitive indicator of precancerous or cancerous changes existing in epithelial cells.