CONCISE REPORT Activation markers of peripheral blood mononuclear cells in late pregnancy and after delivery: a pilot study

Objective: To study the putative shift of a Th1 to a Th2 immune response in pregnancy and its reversal post partum in healthy women and patients with rheumatoid arthritis (RA). Methods: Peripheral blood mononuclear cells (PBMC) were examined by FACS analysis for the expression of activation markers CD25 and HLA-DR and chemokine receptors CXCR3 and CCR4 on CD4+ and CD8+ T cells in four healthy women and four patients with RA. Samples were analysed once in the third trimester and six and 12 weeks post partum. Eight healthy non-pregnant women served as controls. Results: No reduction of CD25 and HLA-DR+ T cells occurred in the third trimester, but a significant increase was observed post partum in healthy women and an even greater increase in patients. Proportions of T cells expressing the CXCR3 or CCR4 marker were similar in patients and controls during pregnancy, whereas a significant increase occurred post partum. The ratio of CXCR3+ to CCR4+ cells remained unchanged during the observation period and did not differ significantly from that in non-pregnant controls. Conclusion: A shift from a Th1 to a Th2 immune response was not detected in the circulation of healthy pregnant women or pregnant patients. The significant increase of T cell activation after pregnancy warrants further investigation into the mechanisms of adjustment of the immune system post partum and its clinical correlates in rheumatic patients.