Abstract: Objective：To study the alteration of the leukocyte differentiation antigens 28/cytotoxic T lymphocyte antigen 4 (CD28/CTLA-4) in maternal blood lymphocyte from patients with early-onset severe preeclampsia to investigate the function of CD28/CTLA-4 in the pathogenesis of early-onset severe preeclampsia. Methods：Peripheral blood from 30 patients with early-onset preeclampsia (PE) [prior to delivery (PTD) and after parturition (AP)]. It applies flow cytometry to detect expression of CD28/CTLA-4 of peripheral lymphocytes in CD4+T and CD8+T cells. At the same time, to determine blood pressure and the functions of liver and kidney. Results：The CD3+CD4+CTLA-4+, CD3+CD8+CTLA-4+ cells in early-onset severe preeclampsia before delivery above after childbirth, CD3+CD4+CD28+/CD3+CD4+CTLA-4+, CD3+CD8+CD28+/CD3+CD8+ CTLA-4+ below after childbirth, was statistically significant (P＜0.05). There isn′t correlation between the CD3+CD4+CD28+/CD3+CD4+CTLA-4+ and CD3+CD8+CD28+/CD3+CD8+CTLA-4+ (r=-0.037, P=0.844). Conclusions：After parturition, the station about the decrease of CTLA-4 and the increase of CD28/CTLA-4 might be relation to early-onset preeclampsia.

Key words: Pre-eclampsia, Antigens, CD28, T-lymphocyte subsets, Th1 cells, Th2 cells, Cytotoxic T-lymphocyte-associated antigen 4