Biphasic effect of testosterone propionate on Sertoli cell secretory function.

When various doses of testosterone propionate (10 to 10,000 mug/day) were given to 21-day-old rats for 10 days a biphasic effect was seen both on testis weight and production of androgen-binding protein (ABP). At low doses (10 to 100 mug testosterone propionate/day) there was a reduction in testis weight as well as ABP content in the epididymis. At higher doses of testosterone propionate, there was a stimulation of both testicular weight and ABP production in spite of suppressed serum FSH and LH levels. These effects of testosterone propionate on Sertoli cell secretory function strongly suggest that the Sertoli cell is a target cell for androgen.

Carcinoma-associated MUC1 detected by immunoradiometric assays.

Fifty-four anti-MUC1 antibodies submitted to the International Society for Oncodevelopmental Biology and Medicine (ISOBM) Workshop (TD-4) were evaluated in immunoradiometric assays, using sera from carcinoma patients and healthy donors. The carcinoma serum pool contained sera from 30 patients with advanced cancer (10 breast, 10 colon, and 10 ovarian). This serum pool contained 696 kU/l MUC1, 770 micrograms/l CEA, and 3,700 kU/l CA 125. The reference serum pool was obtained from 10 healthy women combined with 20 sera from pregnant women, of which half had elevated CA 125 (range 82-254 kU/l). The reference serum pool contained 13 kU/l MUC1, 2 micrograms/l CEA, and 65 kU/l CA 125. The Workshop antibodies were tested both as solid-phase antibodies and as tracer antibodies with the carcinoma serum pool. Twenty-two tracer antibodies and 38 solid-phase antibodies gave at least one combination with > 10% binding of the tracer antibody for a total of 836 combinations. These were tested further with the reference serum pool. Antibodies used as tracers could be separated into three categories: Group 1 antibodies, MF06, MF11, B27.29, MF30, and Ma552, gave mainly 'carcinoma-specific' assays in combinations with the solid-phase antibodies, i.e. binding ratio between carcinoma MUC1 and reference MUC1 > 10. Group 2 antibodies, DF3, 7540MR, A76-A/C7, BC4N154, M38, 7539MR, B12, GP1.4, 232A1, Mc5, and Ma695 gave both 'specific' and 'nonspecific' binding ratios depending on the solid-phase antibody used. Group 3 antibodies, 214D4, BC4E549, E29, BCP8, BC3, and 3E1.2, gave mainly 'nonspecific' combinations, i.e. ratios < or = 10. All antibodies used to capture MUC1 on the solid phase gave both 'specific' and 'nonspecific' combinations depending on the tracer antibody used. Ten antibodies were clearly more efficient as solid-phase capture antibodies; Ma695, B12, M38, GP1.4, 214D4, MF06, B27.29, A76-A/C7, BC3, and KC4. Our findings indicate that the ability to detect 'carcinoma-specific MUC1' cannot be deduced from epitope specificity alone.

Protein epitopes in carcinoembryonic antigen. Report of the ISOBM TD8 workshop.

To characterize antigenic sites in carcinoembryonic antigen (CEA) further and to investigate whether there are differences between colon tumor CEA and meconium CEA (NCA-2) that can be detected by anti-CEA monoclonal antibodies (MAb), 19 new anti-CEA MAb were analyzed with respect to specificity, epitope reactivity and affinity. Their reactivities were compared with 10 anti-CEA MAb with known CEA-domain binding specificity that have previously been classified into five nonoverlapping epitope groups, GOLD 1-5. Cross-inhibition assays with antigen-coated microtiter plates and immunoradiometric assays were performed in almost all combinations of MAbs, using conventionally purified CEA (domain structure: N-A1B1-A2B2-A3B3-C) from liver metastasis of colorectal carcinomas, recombinant CEA, meconium CEA (NCA-2), truncated forms of CEA and NCA (CEACAM6) as the antigens. The affinity of the MAbs for CEA was also determined. The new MAbs were generally of high affinity and suitable for immunoassays. Three new MAbs were assigned to GOLD epitope group 5 (N-domain binding), 3 MAbs to group 4 (A1B1 domain), 1 to group 3 (A3B3 domain), 3 to group 2 (A2B2 domain) and 3 to group 1 (also the A3B3 domain). Three MAbs formed a separate group related to group 4, they were classified as GOLD 4' (A1B1 domain binding). The remaining 3 MAbs appear to represent new subspecificities with some relationship to GOLD groups 1, 2 or 4, respectively. Five MAbs, all belonging to epitope group 1 and 3, reacted strongly with tumor CEA but only weakly or not at all with meconium CEA, demonstrating that the two products of the CEA gene differ from each other, probably due to different posttranslational modifications.