| Abstract: | PROBLEM: Immunophenotypic profiles of perforin (P)-positive peripheral blood lymphocytes in the first trimester and at the term of human pregnancy were analyzed. METHOD OF STUDY: Perforin expression in peripheral blood lymphocyte subsets was measured by simultaneous detection of P (intracellular antigen) and cell-surface antigens (CD3, CD4, CD8, CD16, and CD56) by flow cytometry in nonpregnant (NP) and pregnant women in the first trimester (FTP) and at the time of parturition (TP). RESULTS: The percentage of total P+ cells in peripheral blood compared to nonpregnant women was slightly lower in the FTP but significantly higher at TP. Perforin-positive cells were significantly elevated in T lymphocyte subsets (CD3+P+, CD4+P CD8+P+) in both the FTP and TP groups, as was the percentage of CD56+P+ cells. Profound changes in the CD16+ subpopulation were found in the FTP group compared to both the NP and TP groups (a drastic decrease of CD16+P+ cells; CD16+ cells among P+ cells; P+ cells among CD16+ cells). A considerable part of CD3+ cells in both the FTP and TP groups are CD3+CD56+P+. The average fluorescence intensity (AFI) for P (a measure of P content per cell) was significantly decreased in FTP and increased in TP groups. CONCLUSIONS: The CD16 molecule is FcγRIIIA which is the only Fc receptor responsible for antibody dependent cell-cytotoxicity (ADCC) of NK and T-cells. In the first-trimester human pregnancy this mechanism is severely down-regulated compared to both the NP and TP groups. |
