[Clinical analysis and study of immunological function in syphilis patients with seroresistance].

OBJECTIVE

To investigate the relevant factors of seroresistance of syphilis by clinical analysis and study of immunological function.

METHODS

The clinical data of 172 patients with syphilis were analyzed to observe the correlation of seroresistance with the factors including original titer of rapid plasma regain (RPR), disease course, and medication. Flow cytometry was used to analyze the proportions of T-lymphocyte subset and NK cells in the peripheral blood of 40 untreated syphilitic patients at various stages, 20 syphilitic patients whose serology turned negative after treatment, 20 serum resistance patients, and 18 healthy controls.

RESULTS

The seroresistance rate was 8.7% in the primary syphilis patients (2/23), significantly lower than that of the latent syphilis patients (42.2%, 38/90, P = 0.001). The seroresistance rate of the patients treated with benzathine penicillin was 26.4% (42/159), significantly lower that of the patients treated with macrolides (76.9%, 10/13, P = 0.000). The proportion of CD8(+) T cells of the untreated syphilitic patients was (30% +/- 8%), significantly higher than that of the normal controls [(24% +/- 4%), P < 0.01]. The proportion of NK cells of the untreated syphilitic patients was (13% +/- 5%), significantly lower than that of the normal controls (16% +/- 6%, P < 0.05). The proportion of CD3(+) T cells of the patients whose serology turned negative after treatment was (71% +/- 7%), significantly higher than that of the normal controls (65% +/- 7%, P < 0.05). The proportion of CD8(+) T cells of the patients whose serology turned negative after treatment was (29% +/- 7%), significantly higher than that of the normal controls (24% +/- 4%, P < 0.01). There were not significant differences in the proportions of different cells among the patients with seroresistance, serological negative conversion, and normal controls.

CONCLUSION

Syphilis patients with a high baseline RPR titer, a latent course and macrolide therapy are prone to be seroresistant. Whether the occurrence of serum resistance is related to the inhibition of cell-mediated immunity requires further exploration.