[Study of the immune profile of pregnant women].

During pregnancy, the fetus is an hemiallograft perfectly tolerated by the mother. With the aim of elucidating the mechanism of this tolerance, we have looked to see whether lymphocyte subsets are modified by pregnancy. Using monoclonal antibodies and flow cytometry, we have studied the changes in the immune profile of normal pregnant women and compared them with non pregnant women. In pregnant women, a significant decrease in the percentage of CD3+ cells is observed in the first trimester (61.1 +/- 14.7% versus 73.8 +/- 6.8%; p less than 0.001). The same data are obtained for CD4+ cells (38.2 +/- 10.7% versus 44.0 +/- 7.0%; p less than 0.05) and CD8+ cells (22.8 +/- 5.6% versus 28.0 +/- 8.9%; p less than 0.05). On the other hand, B lymphocytes (CD19+), monocytes (Leu M3+) and natural killer (NK) cells (Leu7+) remain stable during pregnancy. CD11a+ cells decreased during the 1st and 2nd trimesters. Lastly, activated T lymphocytes (CD3+DR+, CD8+DR+) are not modified. Using absolute numbers, a significant decrease is shown only for CD3+ cells in the 2nd and 3rd trimesters and for CD11a+ cells in the 2nd trimester of pregnancy. The decrease of T lymphocyte subsets, NK and CD11a+ cells during pregnancy partially explains the tolerance for the fetus.