TREG Cells are highly regulated through the menstrual cycle: Implications in Human Reproduction

L. ARRUVITO, M. SANZ, M. BARBOZA, L. FAINBOIM

Austria

Congreso; 4th European Congress of Reproductive Immunology; 2006

Medical University of Graz

st1:*{behavior:url(#ieooui) } <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Regulatory T cells (Treg) represent an active mechanism to suppress autoreactive T cells that escape central tolerance. CD4+ T cells with high expression levels of CD25 (CD4+CD25high Treg) have been isolated from human blood, peripheral lymphoid organs, umbilical cord blood, and thymus. Phenotypically, they constitutively express CD25, GITR, CTLA-4 and the transcription factor fork head box P3 (FOXP3). Functional characteristics are hyporesponsiveness to T-cell receptor (TCR)- mediated stimulation and cytokine- independent, cell contact dependent suppression of co cultured CD25- T cell.       Pregnancy constitutes a major challenge to the maternal immune system, because it needs to tolerate the persistence of paternal alloantigen. Treg cells, are also able to suppress antigen-specific immune responses and participate in  allograft tolerance. During pregnancy, hormonal changes might provide an explanation for the enhanced maternal Treg development during fetal gestation because pregnancy-associated hormones, such as estradiol and progesterone, promote immunosuppression.