TGF-BETA-2 IN RABBIT BLASTOCOELIC FLUID REGULATES CD4 MEMBRANE EXPRESSION - POSSIBLE ROLE IN THE SUCCESS OF GESTATION

PROBLEM: During pregnancy, major changes occur in the decidual cell po pulation. One of these changes involves some phenotypical transformati ons of lymphocyte sub-populations. Since these variations might be due to the presence of the embryo, the current study was designed to inve stigate the implication of blastocoelic fluid (BF) in these changes an d to determine the mechanism by which this phenomenon occurs. METHOD: Lymphocytes isolated from human peripheral blood (PBL) were cultured f or 72 h in RPMI-FCS 10% and with or without BF day 12 (BF d-12) or Con canavalin A (ConA). After 72 h, T cells were labelled with anti-CD4 an tibodies and Quantum Simply Cellular microbeads were used as a standar d to evaluate the antibody binding capacity (ABC). RESULTS: Treatment of human PBL with BF d-12 decreases the percentage of CD4 and TCR posi tive cells, as compared to non-stimulated cells, but has no significan t effect on CD2, CD3, and CD8 positive cells. It was also demonstrated , for the first time, that transforming growth factor beta-2 (TGF beta 2) in BF day 12 diminishes the percentage of CD4 positive cells by do wnregulating CD4 membrane expression on leucocytes. CONCLUSION: These findings suggest that the embryo plays a key role in its own protectio n. Furthermore, it is predicted that any tissue producing TGF beta 2, such as certain types of tumor, downregulates the immune response, thu s allowing tumor growth.