[Immunohistochemical analysis of the expression of HLA on the trophoblast of normal pregnancy].

The expression of MHC class II antigens (HLA-DR, -DP, -DQ) on trophoblast was analyzed by an immunoperoxidase technique using monoclonal antibodies. Tissues were obtained after pregnancy hysterectomy with the medical indications and after normal deliveries. They were snap-frozen in liquid nitrogen, cut in a cryostat and fixed in acetone for 10 minutes. Mouse monoclonal antibodies used in this study were anti-HLA-ABC (W6/32, Sera lab), anti-HLA-DR (Cappel), anti-HLA-DP (B7/21, Becton Dickinson) and anti-HLA-DQ (anti-Leu-10, Becton Dickinson) in addition to anti-cytokeratin (CAM5.2, Becton Dickinson) to recognize trophoblast. In the first trimester, HLA-DP could be identified on cytotrophoblastic cell column, cell island, extravillous trophoblast invading the decidua basalis, which were positive for HLA-ABC, and villous cytotrophoblast. In term placenta, villous syncytiotrophoblast and extra-villous trophoblast found in the decidua were positive for HLA-DP. In contrast, no trophoblast reacted with anti-HLA-DR or anti-HLA-DQ.