RESUMO
Objective:To investigate the possible role of NKT cells in unexplained recurrent spontaneous abortion by measuring the NKT cell numbers,maturity and cytokine secretion of the placenta of mice with unexplained recurrent spontaneous abortion.Methods:Normal pregnancy model in hybrid by feeding CBA / J and BABL/C in a cage,and the model of unexplained recurrent spontaneous abortion was established by feeding CBA / J and DBA2/J in a cage.The number of NKT and CD3~+T cells was determined by flow-cytometry;Th1/Th2-relative cytokines were assayed by ELISA and T-bet expression was determinded by fluorescence quantitative PCR.Results:There was not significant change of CD3~+ T cells when compared between normal pregnancy and unexplained recurrent spontaneous abortion group (P＞0.05).In the course of normal pregnancy,the IFN-γ secreted by placenta lymphocytes decreased gradually,accompanied by the decline of NKT cell number and the proportion of mature cells;whereas in the course of unexplained recurrent spontaneous abortion,it was on the opposite.There was significant difference of T-bet mRNA expression between the two groups.T-bet mRNA expression was related to the proportion of mature NKT cells or placenta IFN-γ secretion by lymphocytes.Conclusion:Unexplained recurrent spontaneous abortion may be related to NKT cells disorders,NKT cells are of low-mature proportion and inadequate secretion of IFN-γ during early pregnancy,whereas are shown high-mature proportion and excessive secretion of IFN-γ during latter pregnancy;the anomaly of T-bet mRNA expression may be one of the factors leading to NKT cells disorder.