Abstract: Objective To characterize the human cell mediated immune response to Treponema pallidum(TP),and to determine the effect of TP infection on the various lymphocyte subpopulations and natural killer cells in the peripheral blood of the patients.Methods Twenty four untreated patients with early syphilis were analyzed,including 3 groups of 8 patients with disseminated syphilides,palmoplantar syphilides and latent syphilis each.Monoclonal antibodies of CD labeled with either fluorescein isothiocyanate or phycoerythrin were used on a flow cytometry to detect the changing of peripheral blood lymphocyte immunophenotypes.Results The results showed that the percentages of panT,T H,NK cells and the ratio of T_H/T_S were significantly lower (P<0.01) and those of T_S cells were significantly higher (P<0.01) than those of normal controls.No statistical difference of the immunophenotype distribution was found among groups of disseminated lesions,palmoplantar syphilides,and latent syphilis (P>0.05).Conclusion It suggests that there is prominent suppression of cellular immunity in the untreated patients suffering from early syphilis.Meanwhile,the difference of 3 groups in skin lesions was due to the different dermatobarrier function against the systemic invasion of TP,rather than attributed to the alteration of the lymphocyte immunophenotypes in the peripheral blood.

Key words: Syphilis, Lymphocyte immunophenotype, Flow cytometry