Detection by direct immunofluorescence of antibodies to Treponema pallidum in the cutaneous infiltrates of rabbit syphilomas.

By direct immunofluorescence, with use of fluorescein-labeled sonified Treponema pallidum, specific antibodies were detected in the tissue infiltrates of cutaneous syphilomas in rabbits. Specimens from cutaneous and mucosal inflammatory lesions induced by intradermal injection of a keratinous substance from an epidermal cyst served as controls. Granular fluorescence was detected in the dermis of 11 of the 12 syphiloma specimens and corresponded to areas of heavy plasma cell infiltrates, and some fluorescence was found directly on plasma cells identified by subsequent staining with hematoxylin and eosin. This fluorescence could be blocked by preabsorption. Control slides did not show any fluorescence. Immunopathologic techniques using labeled antigens may be of diagnostic value in syphilis and other infectious disorders which feature specific infiltrates.