IMMUNOHISTOCHEMICAL LOCALIZATION OF TRANSFORMING GROWTH-FACTOR-BETA IN HUMAN IMPLANTATION SITES

Transforming growth factor-beta (TGF beta), a protein known to antagon ize many of the functions of the epidermal growth factor-receptor syst em, was localized immunohistochemically in unruptured ectopic pregnanc ies (EP) removed by salpingectomy (n = 8), uterine decidua from EP (n = 4), and decidua and trophoblast from electively terminated first tri mester pregnancies (ETP; n = 8). Two rabbit polyclonal antisera that r ecognize both TGF beta 1 and beta 2 were used. Immunostaining for TGF beta was identified in all three forms of trophoblast, cytotrophoblast s, intermediate trophoblasts, and syncytiotrophoblasts, which were dif ferentiated histologically and immunohistochemically. Moderate cytopla smic immunostaining was found in villous cytotrophoblasts in both EP a nd ETP. Nonvillous (anchoring) cytotrophoblasts in these same tissues demonstrated moderate immunostaining adjacent to the villous and light immunostaining distal to the villous. In intermediate trophoblasts, m oderate to intense immunostaining was seen in EP and ETP. Syncytiotrop hoblasts demonstrated moderate cytoplasmic immunostaining in EP and ET P as well as moderate to intense staining of plasma membranes and micr ovilli. Nuclear staining was not evident in any form of trophoblast. T GF beta immunostaining was demonstrated in both glands and stroma of d ecidua from both EP and ETP; however, staining was more intense in dec idua from ETP. With the known presence of TGF beta receptors and mRNA in placenta, these results suggest an autocrine/paracrine sole for TGF beta regulation of endometrial-trophoblast function during human impl antation.