Abstract: Objective To explore the possible formation mechanism of early syphilitic lesions.Method The lesions of 30 early syphilitic cases were examined by means of routine pathology,silver staining and immunohistochemistry to observe the pathological changes in the lesions and to locate Treponema pallidum as well as the expression ofTh1/Th2 cytokines.Results There were typical syphilitic pathological changes,and presence of T.pallidum in chancre and in different types of secondary syphilitic lesions except maeula.Th1 cytokines were predominant in chancre.In secondary syphilitic lesions the expression of Th1/Th2 cytokines varied according to the duration of the infection.Th2 cytokines were often seen in those lesions of long duration,except macular lesions.The expression of Th2 cytokines in macular lesions was not related to the duration of infection.Conelusion The macular lesions of secondary syphilis may be caused by hypersensitive reaction.

Key words: Syphilis, Treponema pallidum, Interleukin-2, Interleukin-4, Interleukin-10, Interfer-on TypeⅡ