Acid phosphatase localization in prostatic carcinoma. A comparison of monoclonal antibody to heteroantisera

A series of 39 prostatic carcinomas was characterized in terms of grade, stage, histologic pattern, and serum acid phosphatase values. These cases were studied immunohistochemically with two different heteroantisera, a goat and rabbit antiserum, and with a monoclonal antibody to prostatic acid phosphatase (PAP). Eighty‐three percent of carcinomas had some degree of PAP positivity when stained by the goat anti‐PAP. Seventy percent were positive with the rabbit antiserum, and 59% showed positivity with the monoclonal antibody. Microacinar patterns were consistently the most positive for PAP, followed by cribriform patterns. The least positivity was observed in the undifferentiated, singlefile and sheet‐like patterns. Likewise, there was more PAP positivity in the lower Gleason and Mostofi grades. When the serum PAP positivity (done by counterimmunoelectrophoresis [CIEP]) was compared with tissue positivity (using the same goat antiserum), 37% were positive in both serum and tissue; 48% were negative in serum, but positive in tissue; and in only 9% the tissue sample was negative when the serum was positive. Based on these data, conclusions are drawn about the significance of the serum acid phosphatase elevations and the role of monoclonal antibodies and heteroantisera in clinical–diagnostic and research work.