Fig. 1.

Pregnancy imparts CD4⁺ T cell awareness. (A) Splenocytes harvested from virgin (8 weeks old, n = 4) and previously bred (14 weeks old, n = 4) C57BL/6 mice from the same colony: Cellular proliferation assay 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), the I-A^b presented lysteriolysin peptide epitope (10 μM Lso), or no peptide stimulation. Cultures were pulsed with 1 μCi per well ³[H]TdR for the final 18 h of a 72-h culture (cpm ± SD). Statistical difference determined by one-way ANOVA with Bonferroni–Dunn posttest (N.S., nonsignificant; *, P < 0.05). Pregnancy primes maternal CD4⁺ T cell awareness in proportion to fetal antigenic mass. (B) Splenocytes harvested from virgin 8-week-old C57BL/6 mice (8 weeks, n = 4) and timed first pregnancy of 8-week-old female C57BL/6 × C57BL/6 males (n = 4 each time point) at days post coitus (dpc 6.5, 12.5, 18.5): Cellular proliferation assay 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 1 μCi per well ³[H]TdR for final 18 h of a 72-h culture. Composite fold increase in proliferation with Dby/Lso ± SEM. Statistical difference determined by one-way ANOVA with Bonferroni–Dunn posttest (*, **, #, P < 0.05). (C) Days postcoitus 6.5. Splenocyte proliferative response determined for individual mice ± SD along with fetal gender determination. (D) Days postcoitus 12.5. (E) Days postcoitus 18.5. Statistical difference determined by two-tailed, unpaired Student's t test (N.S., nonsignificant; *, P < 0.05).