Allogeneic reactivity of maternal lymphoid cells during the course of gestation. Modifications and sex differences in a local GVH assay.

The immune reactivity of lymphoid cells from pregnant mice was studied during the course of pregnancy in primiparous and multiparous animals either " isopregnant " (male and female of same strain) or " allopregnant " (male and female differing at H-2), using a local GVH assay (CBA lymphoid cells injected into (CBA X A/J)F1 recipients). The findings were as follows: The lymphoid cell number in the para-aortic lymph nodes ( PALN ) was increased at all stages of gestation. The peak occurred in the 2nd week in primiparity and as early as 60 h after fertilization in multiparity. PALN cell alloreactivity was weak at the beginning and higher than normal in the third week of pregnancy. Spleen cell alloreactivity was increased in the second week and decreased in the third week in primiparous compared with multiparous animals. Anti-paternal alloreactivity exhibited by spleen cells of allogestation was decreased (as compared to cells of isogestation ) especially in primiparous mice, particularly in the third week. At this time, the anti-paternal alloreactivity of PALN cells was increased. The influence of the recipient's sex on GVHR intensity was reversed when the cells were obtained from a pregnant donor, becoming stronger in male compared with female hybrids.