Abstract:

To explore the influence of tumor cells in the number and function of CD4+CD25+Treg cells.
Methods  Lewis lung cancer cells and mouse spleen lymphocytes co-culture system was established.Lewis lung cancer cells with different concentrations of lymphocytes co-cultured were divided into 4 groups:experimental group Ⅰ(5×105 Lewis lung cancer cells and 1×106 lymphocytes c
o-culture),control group Ⅰ(1×106 lymphocytes culture),experimental group Ⅱ(5×105 Lewis lung cancer cells and 2×106 lymphocytes co-culture),control group Ⅱ(2×106 lymphocytes culture);Lewis lung cancer cells were co-cultivated with lymphocytes for different time, 24,48, and 72 h three time points were selected.Lewis lung cancer cells culture supernatant was co-cultivated with lymphocytes,the concentrations of culture supernatant were 20% and 50%.The number changes of CD4+CD25+Treg cells in the co-culture system of Lewis lung cancer cells and splenic lymphocytes were detected by flow cytometry;the expression of Foxp3 mRNA after co-culture was detected by RT-PCR method.
Results Compared with control group,the number of CD4+CD25+Treg cells and the expression of Fo
xp3 mRNA were significantly increased in experimental group Ⅰ (P<0.05),and ther
e was no significant difference in experimental group Ⅱ (P>0.05);24　and 48 h 　
after co-culture of Lewis lung cancer cells and lymphocytes,the number of CD4
+CD25+Treg cells and the expression of Foxp3 mRNA were significantly increased (P<0.05),
and there was no significant changes at  72 h;20% and 50% Lewis lung cancer cells supernatant could significantly increase the number of CD4+CD25+Treg cells and Foxp3 mRNA expression (P<0.05).Conclusion Tumor cells and their supernatants could induce the increase of the number of CD4+CD25+Treg cells  and their function,this might be one of mechanisms of tumor-induced immune tolerance.

Key words: CD4+CD25+Treg cells;Foxp3;tumor immunity