Immunophenotypes, apoptosis, and expression of Fas and Bcl-2 from peripheral blood lymphocytes in patients with secondary early syphilis.

OBJECTIVES

Whether syphilis influences lymphocyte apoptosis has not been reported so far.

GOAL

The goals of this study were to determine whether syphilis influences lymphocyte apoptosis and to investigate the molecular mechanism of apoptosis.

STUDY DESIGN

Peripheral blood lymphocyte (PBL) immunophenotypes, apoptosis, and expression of Fas (CD95) and Bcl-2 were detected by flow cytometry in 33 patients with secondary early syphilis and 30 healthy subjects.

RESULTS

Compared with the control subjects, the percentage of CD4 T cells and the ratio of CD4:CD8 were significantly decreased, and that of CD8 T cells and the apoptotic rates of PBLs and CD4 T cells were obviously increased in syphilitic patients. Fas overexpression and Bcl-2 downexpression in the syphilitic group were observed in PBLs and CD4 cells but not in CD8 and CD19 cells.

CONCLUSIONS

The increased apoptosis of PBLs and CD4 T cells by Fas-mediated death pathway and downexpression of Bcl-2 protein could account for immune dysfunction in secondary early syphilis, which is responsible for the incomplete clearance of Treponema pallidum from the lesions and the chronic infection.