FACS analysis of changes in T and B lymphocyte populations in the blood, spleen and lymph nodes of pregnant mice.

Using the fluorescence-activated cell sorter (FACS), the percentages of T and B lymphocytes in the peripheral blood, spleen and lymph nodes of CBA syngeneic and allogeneic pregnancies were determined. At 19 days of syngeneic pregnancy, the level of T cells in the blood had decreased and that of B cells had increased. In the spleen, a decrease in both T and B cells occurred earlier in pregnancy and had returned to control levels by 19 days. During the last few days of pregnancy, the para-aortic lymph nodes (PALN) draining the pregnant uterus of syngeneically mated mice showed a 1 . 7-fold increase in the level of B cells over that in virgin controls. The T-cell level dropped at the end of pregnancy by approximately 10%. There was no change in T- or B-cell status in the brachial (underarm) nodes taken from the same animals.