IMMUNOHISTOCHEMICAL EVALUATION OF ESTROGEN AND PROGESTERONE RECEPTORSIN PARAFFIN-EMBEDDED, FORMALIN-FIXED ENDOMETRIAL TISSUES - COMPARISONWITH ENZYME-IMMUNOASSAY AND IMMUNOHISTOCHEMICAL ANALYSIS OF FROZEN TISSUE

Monoclonal antibody (MoAb) 1D5 with specificity to the estrogen recept or (ER), MoAb 1A6, and a polyclonal antibody (PoAb) (the latter two wi th specificity to the progesterone receptor [PgR]) were used to stain microwave-pretreated sections of formalin-fixed, paraffin-embedded nor mal and malignant endometrial tissues (n = 60), The tissues were previ ously evaluated for ER and PgR by enzyme immunoassay (EIA) (n = 44) an d immunohistochemical analysis of frozen tissue (ICA(froz), n = 59), W ith results of EIA as a reference, the ER-1D5 method yielded a better agreement on receptor status, i.e., positive versus negative (74 vs. 5 1%) and a higher sensitivity (71 vs. 45%) but a similar high specifici ty (100%) than the ER-ICA method. Compared with results of PgR-EIA, th e immunohistochemical assays for PgR gave similar results as to agreem ent (86-95%) and sensitivity (95-97%), Quantitative agreement on the f raction of cells stained for ER and PgR by immunohistochemical analysi s in frozen and formalin-fixed tissue was obtained in approximately 60 % of the cases. The results of semi-quantitation were correlated with the results of both ICA and EIA, The MoAbs 1D5 and 1A6, as well as the anti-PgR PoAb, thus seem to be valid for evaluation of ER and PgR sta tus in formalin-fixed endometrial tissue. Differences in the specifici ty of the Abs and in the sensitivity of the methods used to demonstrat e ER and PgR might explain some of the discordant findings.