Demonstration by labeled treponemal antigen of specific antibodies in the tissue infiltrates of secondary syphilis.

Specific antitreponemal antibodies have been demonstrated by immunofluorescence techniques in the lymphoplasmocytic infiltrates which characterize early symphilitic lesions. A purified suspension of Nichols strain Treponema pallidum was sonified and labeled with fluorescein isothiocyanate and applied to cryostat sections of 12 biopsy specimens from the cutaneous lesions of 11 patients with proven secondary syphilis, using a modified direct immunofluorescence procedure. Specimens from various inflammatory dermatoses processed similarly served as controls. Granular fluorescence was noted in the dermis in 9 of the 12 specimens corresponding to areas of heavy plasma cell infiltration and some fluorescence was found directly on plasma cells which were identified by subsequent hematoxylin and eosin staining. This fluorescence could be blocked by prior incubation of the sections with unlabeled sonified treponemal suspension. Control slides did not reveal any fluorescence. The use of labeled treponemal antigen may aid the tissue diagnosis of early syphilitic lesions which can mimic a variety of dermatological disorders.