Depression of Mitogenesis and Mixed Lymphocyte Reactivity of Maternal Lymphocytes during Pregnancy in Cynomolgus Monkeys

Abstract

In vitro responses of lymphocytes to PHA, ConA and PWM as well as the mixed lymphocyte reactivity (MLR) were determined with 83 pregnant cynomolgus monkeys (Macaca fascicularis) from 39 to 157 days of gestation age. The mitogenesis to PHA in pregnant monkeys was significantly lower during 5 to 8 weeks and more than 20 weeks after conception than in non-pregnant animals. The responses to ConA and PWM did not change during the first 18 weeks of gestation, but decreased remarkably after 20th week.
The mixed lymphocyte reactivity was also significantly decreased after 20 weeks of gestation age. This highly significant reduction was observed regardless of the origin of stimulator cells; mated male lymphocytes or third party male lymphocytes. This finding suggests that the depression of MLR in the present study is not specific to fetal histocompatibility antigens but nonspecific. In addition, MLR was apparently suppressed when maternal lymphocytes were incubated with autologous serum (pregnant serum) as compared with that when incubated with pooled young male serum. From these results, it can be postulated that the mixed lymphocyte reactivity of maternal lymphocytes is suppressed by some soluble factors that may be contained in pregnant serum 20 or more weeks after conception.