Objective: To study the localisation of treponemes and to analyse the inflammatory infiltrate in biopsy specimens from patients with primary or secondary syphilis, or early infectious yaws.
Materials and methods: Skin biopsies originating from human lesions of primary (29x) or secondary (15x) syphilis (Rotterdam), or early yaws (18x) (West Sumatra) were studied. Different histochemical and immunohistochemical detection methods were used in this study.
Results and conclusion: The histochemical silver staining method according to Steiner revealed the presence of T. pallidum in all cases of primary syphilis studied. In 10 out of 14 cases of secondary syphilis, treponemes were demonstrated. With an immunofluorescence staining technique (IF) using anti-T. pallidum antiserum raised in rabbits (a-Tp), T. pallidum was demonstrated in 28 out of 29 cases of primary syphilis, and in 14 out of 14 studied cases of secondary syphilis. The silver staining method and IF showed identical localisations of T. pallidum (mainly in the dermal-epidermal junction zone or throughout the dermis). Using a-Tp antiserum in the indirect immunofluorescence technique, T. pertenue could be demonstrated in the dermis more often than with Steiner silver staining. However, epidermotropism of T. pertenue in yaws specimens was remarkable, compared with more mesodermotropism of T. pallidum; numbers of T. pertenue in the dermis were limited in all specimens. The dermal inflammatory infiltrate in primary and secondary syphilis was composed mainly of lymphocytes and plasma cells. In most cases more T (CD3 positive) cells than B (CD22 positive) cells were present. Regarding T cell subpopulations, in primary syphilis, T helper/inducer (CD4 positive) cells predominated in 86% of cases. In secondary syphilitic lesions, numbers of T helper/inducer cells were less frequent than or equal to T-suppressor/cytotoxic (CD8 positive) cells in 60% of cases. Remarkably, in yaws specimens the inflammatory infiltrate consisted mainly of IgG, but also IgA and IgM producing plasma cells. T or B lymphocytes were scarce, which is in sharp contrast with findings in syphilitic lesions.