A new marker for human cancer cells, 2 immunohistochemical detection of the Ca antigen in human tissues with the Ca1 antibody.

The Ca1 antibody has been used in an immunohistochemical procedure to detect the Ca antigen in sections of tissues routinely embedded in paraffin wax. A representative sample of benign and malignant tumours from all the systems of the human body has been examined. The majority of malignant tumors express the Ca antigen. The exceptions are: prostatic carcinomas, testicular teratocarcinomas and seminomas, some sarcomas, some lymphomas, malignant brain tumours, neuroblastomas, and melanomas. The antigen is least readily detected in epithelial malignancies of the alimentary system, particularly of the colon. The Ca1 antibody does not react with any benign tumour. The only normal tissues that react specificity with this antibody are the epithelium of the fallopian tube and the transitional epithelium of the urinary tract. The Ca1 antibody also readily distinguishes malignant cells in smears of malignant effusions. These findings indicate that the Ca1 antibody may be useful in the diagnosis of malignancy in routine clinical practice where the morphological interpretation of the biopsy or cytological smear is in doubt.