Evaluation of commercial immunoperoxidase kits in diagnosis of prostate carcinoma

Comparison of one commercial immunoperoxidase kit for prostate specific acid phosphatase (PSAP) and two for prostate specific antigen (PA) with an unlabelled antibody peroxidase-antiperoxidase (PAP) technique using rabbit antihuman PSAP revealed generally good reproducibility of results on formalin fixed, paraffin-embedded sections of primary and metastatic prostatic carcinoma. Frequency of positivity was 92 per cent with both our noncommercial PAP and the kit method for PSAP, and 82 per cent and 89 per cent with kits for PA. Thus, sensitivity, with the PA kits was less than with our noncommercial PAP and the kit PSAP, with less intense immunostain and occasional false negatives. Specificity was good with all three kits, and no false positive results were obtained. Commercial immunoperoxidase kits provide a relatively easy and inexpensive means for practicing pathologists in a service-oriented setting to make more precise diagnoses in cases of poorly differentiated or metastatic carcinoma of prostatic origin.