Fig. 3.

Pregnancy results in a functional T regulatory response in proportion to the fetal mass. (A) Splenocytes harvested from a timed first pregnancy of a 6-week-old C57BL/6 × C57BL/6 male at dpc = 18.5 (six male fetuses). Splenocyte proliferative response determined for individual mice ± SD. (B) Splenocytes from virgin 6-week-old C57BL/6 (no prior plugs). Treg depletion by magnetic bead separation of CD25⁺ cells. Cellular proliferation assay was performed using 1 × 10⁶ cells per mL to the CD4⁺ T cell peptide epitope of the H-Y antigen presented by I-A^b (10 μM Dby) or the I-A^b presented lysteriolysin peptide epitope (10 μM Lso). Cultures were pulsed with 1μCi per well ³[H]TdR for the final 18 h of a 72-h culture (cpm ± SD). Statistical difference determined by two-tailed unpaired Student's t test (N.S., nonsignificant; *, P < 0.05). (C) Splenocytes from virgin, timed first pregnancy of C57BL/6 × C57BL/6 (8 weeks old, n = 4 each time point) dpc 6.5, 12.5, and 18.5, or 14-week-old retired breeder (parous). Depletion of CD25⁺ cells (Treg) by magnetic bead. Composite fold increase in proliferation with Dby (CD25⁺ depleted)/Dby (whole splenocytes) ± SEM. Statistical difference determined by one-way ANOVA with Bonferroni–Dunn posttest (*, **, #, †, ‡, P < 0.05).