[Initial experiences with a monoclonal antibody to the progesterone receptor complex].

Today, the immuncytochemical demonstration of estrogen receptors can be regarded as established. Recently, a monoclonal antibody (mab) against the progesterone receptor-complex became commercially available. The antibody Mi 60-10, developed by Milgrom and co-workers, is murine and principally directed against the progesterone receptor of the rabbit, but it also attacks an "epitop" of the human receptor. The Western-Blot analysis shows the antibody having several specific bands against T-47-D cells in the region of 110,000 dalton. To estimate the practical performance of this antibody, 73 primary breastcarcinomas were incubated with both the ER-ICA-Kit and the new "mab". The PAP method was used for visualisation. In a frozen section the mab Mi 60-10 proved as successful as the ER-ICA-Kit. However, in contrast to the ER-ICA-Kit, the mab Mi 60-10 is also successful in locating the receptor, also in formalin-fixed samples embedded in paraffin. This is also the case with blocks, which were stored for several years. In aspirated cytological samples the immunocytochemical demonstration of progesterone was just as successful as that of estrogen and comparable with results on the histological section. A satisfactory validity can be obtained today through the development of highly specific monoclonal antibodies against the progesterone receptor complex, with the complete receptor diagnosis of mammary carcinoma both immunocytochemically in frozen sections and additionally, of progesterone receptors in paraffin wax sections. The only current problems involve the exact quantification of the immunocytochemical results. It is predictable today, that the DCC-method, when compared to the immunocytochemical receptor analysis, will reduce in significance.