Abstract: Objective To investigate the effects of arsenic trioxide (ATO) on anti-dsDNA antibody and lymphocyte subsets proliferation in splenic cells of MRL/lpr mice. Methods The MRL/lpr mice were divided into three groups: ATO group (0.4mg/kg·d, ip), sodium chloride (NS) group (0.25ml,ip), and cyclophosphamide (CTX) group (50mg/kg·qw, ip). The additional control group consisted of 12 syngeneic normal C57/BL mice, which were divided into two groups: ATO group (0.4mg/kg·d, ip) and NS group (0.25ml,ip). Each group contains 6 mice. After two months' treatment, all mice were killed and their bodies and spleens were weighed. The levels of anti-dsDNA antibody in serum were detected by ELISA. The percentages of different cell subsets were detected by flow cytometry. Results (1)The spleen index、serum levels of anti-dsDNA antibody and the percentages of CD19+、CD3+、CD3+CD4+ lymphocytes in ATO group were much lower than that in NS group of MRL/lpr mice(P<0.01or P<0.05), while the percentage of NK cells was the higher (P<0.05). (2)The spleen index and the percentages of CD3+CD4+ lymphocytes in ATO group were obviously lower than that in CTX group of MRL/lpr mice(P<0.01). The serum levels of anti-dsDNA antibody is lower both in ATO group and CTX group, and it is was higher in ATO group than that in CTX group(P=0.033). (3)There was no difference between ATO group and NS group in C57/BL mice(P>0.05). Conclusion Arsenic trioxide can inhibit the activation of T and B lymphocytes, increase the percentage of NK cell and reduce the serum level of auto-antibody. And it was of no effect in the normal mice.

Key words: Arsenic trioxide, Systemic Lupus erythematosus, MRL/lpr mice, Lymphocyte subsets, NK cell