人类T细胞的各种防御和调节功能是由表型异源性的亚群所完成的.曾被视为“天然”和“记忆”T细胞的人类互补T细胞亚群所差异表达的膜抗原是共同的细胞抗原家族中的CD45RA和CD45RD.CD45RA最早表达在胸腺内成熟晚期的T系细胞、继而大多数免疫学上天然新生期的T细胞也表达该抗原.随着年龄的增加和抗原的暴露,在循环中CD45RA-RO~+的细胞越来越占优势并成为细胞中的主要细胞. The diverse defense and regulatory functions of human T cells are accomplished by phenotypically heterogeneous subpopulations that have been identified as a subset of human complementing T cells that are “natural” and “memory” T cells The expressed membrane antigens are CD45RA and CD45RD in a common family of cellular antigens. CD45RA is the earliest mature T cell line expressed in the thymus and most of the immunologically naive T cells also express this antigen. Increased and antigen exposure, CD45RA-RO ~ + cells are increasingly predominant in circulation and become the dominant cells in the cell.