Pregnancy-induced expansion of regulatory T-lymphocytes may mediate protection to multiple sclerosis activity

Pregnancy represents a physiological transitory state of immune tolerance to avoid the rejection of the foetus, and concomitantly of stabilisation of many autoimmune diseases, such as multiple sclerosis (MS). Alterations in regulatory T-lymphocytes (T-Reg) are known to be involved in organ-specific autoimmune disease pathophysiology. Our goal was to quantify CD4(+)CD25(+) and CD4(+)CD25(hi+) T-Reg and activated (CD4(+)HLA-DR(+)CD38(+)) T-lymphocytes during pregnancy and puerperium in 13 MS patients in comparison with healthy pregnant and non-pregnant women. During pregnancy, it progressive parallel increase in CD4(+)CD25(+) T-lymphocytes in healthy pregnants as well as MS pregnant patients was observed. The proportion of T-Reg was significantly higher in all pregnants than in non-pregnant women (p=0.01), whereas no differences were observed neither in the percentages of total nor activated CD4(+) T-lymphocytes. In MS patients, CD4(+)CD25(+) T-lymphocytes significantly decreased when comparing the third trimester with the puerperal period proportions (p=0.01), whereas CD4(+)CD25(hi+) T-lymphocytes significantly increased (p=0.002). Our findings are consistent with the expansion of circulating regulatory CD4(+)CD25(+) T-lymphocytes pool with suppressive activity during normal pregnancy and in MS. A different pattern of CD4(+)CD25(hi+) T-lymphocytes between healthy pregnants and MS women, which may represent relevant factors in the activity course of MS. (C) 2004 Elsevier B.V. All rights reserved.