DETECTION OF C-ERBB-2 AND OTHER TUMOR-MARKERS ON BLADDER-TUMOR SPECIMENS - MARKED DIFFERENCES AFTER FORMALIN OR BOUINS FIXATION

In the course of a multi-center retrospective study on the prognostic value of bladder tumor markers, it became apparent that tumor samples from one of the Centers showed reactivity patterns outside the normal range of variability. The antibodies investigated were a rabbit antise rum to c-erbB-2, the monoclonal antibody P12 to LewisX and the monoclo nal antibodies (mAb) M344 and 19A211 to bladder tumor-associated antig ens, The tumor specimens (total=171) were from comparable patient popu lations from each Center. The only difference was in the fixation of t he tumors, done with formalin in three Centers (12 tumors) and with Bo uin's solution (50 tumors) in one Center, Analysis of the results show ed significant differences in the rate of positivity between comparabl e tumors. Positivity of Mab 19A211 with Bouin's tumors was 30% of that with formalin-fixed tumors, while reactivity with the antiserum to c- erbB-2 was four fold more frequent in Bouin's-fixed tumors. The expres sion of these two antigens is clearly different from that expected fro m preliminary results and from other published studies, Thus, tissue f ixation with Bouin's solution can generate artificially high or low re sults with some antibodies. This may have important implications in th e study of tumor markers by immunohistochemistry.