INCREASED EXPRESSION OF CELL-SURFACE MARKERS ON ENDOMETRIAL GAMMA-DELTA T-CELL RECEPTOR(+) INTRAEPITHELIAL LYMPHOCYTES INDUCED BY THE LOCALPRESENCE OF THE SHEEP CONCEPTUS

PROBLEM: In sheep, gamma delta T-cell receptor (TCR)(+) cells are a ma jor lymphocyte subpopulation in the luminal epithelium of the uterine endometrium. During late pregnancy, this population of T cells increas es in number and becomes more granulated. This study was performed to determine whether this apparent activation was induced by local effect s of the conceptus or systemic effects of pregnancy. METHODS: The unil aterally-pregnant ewe, in which the conceptus is surgically confined t o one uterine horn, was used to distinguish between systemic and local effects of pregnancy on function of endometrial gamma delta TCR(+) in traepithelial lymphocytes. Lymphocytes col lected from peripheral bloo d, and from the endometrial luminal epithelium of cyclic and unilatera lly-pregnant ewes (day 140 of gestation) were analyzed by flow cytomet ry. RESULTS: As compared to gamma delta TCR(+) lymphocytes in peripher al blood, gamma delta TCR(+) intraepithelial lymphocytes from non-preg nant ewes had a lower percentage of cells staining positive for CD25, CD44, and L-selectin. There was no effect of pregnancy on the percenta ge of gamma delta TCR(+) peripheral blood lymphocytes staining positiv e for CD25, CD44, CD29, or L-selectin. Similarly, the percentage of in traepithelial lymphocytes staining positive for these antigens was sim ilar for cells collected from cyclic ewes and cells from the nonpregna nt uterine horn of unilaterally-pregnant ewes. In contrast, there was a higher percentage of CD25, CD44, CD29, and L-selectin(+) cells for g amma delta TCR(+) intraepithelial lymphocytes from the conceptus-conta ining uterine horn of pregnant ewes than for gamma delta TCR(+) intrae pithelial lymphocytes from the endometrium of cyclic ewes or from the nonpregnant uterine horn of pregnant ewes. CONCLUSION: The local prese nce of the conceptus causes changes in cell surface marker expression on endometrial gamma delta TCR(+) intraepithelial lymphocytes during p regnancy. These changes may reflect conceptus-induced activation of th is population of cells.