TIME-COURSE ANALYSIS OF ALPHA(-CELL CLONES DURING NORMAL-PREGNANCY()BETA(+) T)

During normal pregnancy, the fetus continues to mature inside the uter us without rejection. Inherited paternal antigens could be targeted by the maternal immune system. These reactions are believed to play a ro le in a number of habitual abortions. However, the precise maternal me chanisms preventing fetal tissue rejection are not well understood. Ma ternal T cells should recognize fetal antigens. so it is conceivable t hat antigen-specific T cell response to fetal antigens would occur by proliferation and accumulation of certain T cell clones in the pregnan t mother. To elucidate the maternal immune response to the fetus, we i nvestigated the clonality of expanded T cells in peripheral blood lymp hocytes in ten normal pregnant women. We employed reverse transcriptas e-polymerase chain reaction for T cell receptor beta chain gene and su bsequently analyzed the PCR product by single-strand conformation poly morphism analysis. A large number of distinctly expanded T cell clones were detected during pregnancy. These accumulations were observed as early as the ninth to tenth week post-conception and reached a maximum during the second trimester. suggesting the existence of dynamic anti gen-specific T cell responses in the pregnant mother. However, after t he 30th week of gestation, nearly all expanded T cell clones disappear ed before parturition and the degree of clonality reached almost norma l levels. Our results clearly indicate the existence of dynamic matern al T cell responses during pregnancy.