Immunocytochemical reaction of Ca1 and HMFG2 monoclonal antibodies with cells from serous effusions.

The Ca1 antibody was used in an alkaline phosphatase immunocytochemical method on cells obtained from 150 specimens of pleural and ascitic fluids. The results were compared with the routine cytology report based on the light microscopical appearances. The Ca1 antibody identified tumour cells in 51 of 57 specimens with malignant cells. The exceptions were four small cell carcinomas, one malignant lymphoma, and one adenocarcinoma. A further seven specimens reported as containing atypical cells but without conclusive evidence of malignancy were Ca1 positive. The Ca1 antibody did not give a positive reaction with benign mesothelial cells. Similar results were obtained with the HMFG2 antibody and malignant cells, but in eight of 18 benign effusions it reacted with mesothelial cells.