A study of CD45RO, CD45RA and CD29 antigen expression on human decidual T cells in an early stage of pregnancy

The decidua is the place where the fertilized egg is implanted and where the immunocompetent cells of the mother come into direct contact with genetically disparate cells of the conceptus. Although the T cells in the decidua are exposed to fetal antigens, the fetus is not rejected by maternal immunocompetent cells. In the present study, we examined surface markers to determine whether the T cells in the human decidua are naive T cells without or memory T cells with a history of antigen stimulation. Although few T cells were present in the decidua, as compared to the peripheral blood, CD45RO⁺, CD29⁺ and CD45RA⁻ CD4⁺ T cells as well as CD45RO⁻, CD29⁺ and CD45RA⁻ CD8⁺ T cells, which are considered to be memory T cells, were in the majority, with only small numbers of CD45RO⁻, CD29⁻ and CD45RA⁺ CD4⁺ and CD8⁺ cells, which are naive T cells, present. Also, the decidual mononuclear cells secreted IL-2 and IL-4. Since IL-4 is secreted only by memory T cells, it is suggested that in the decidua memory T cells increase in number and secrete cytokines, thereby in some way influencing the phenomenon of fertility.