Secondary syphilis in persons infected with and not infected with HIV-1 - A comparative immunohistologic study

To better understand the cutaneous immune response to Treponema pallidum, w e performed an immunohistologic study of skin biopsies from a total of 11 p atients with secondary syphilis; biopsies from five persons infected with H IV-1 were included in the analysis to assess at the tissue level the impact of concomitant HIV-1 infection on disease expression. In all of the biopsi es, staining for HLA-DR, a marker for cellular activation, was observed amo ng infiltrating leukocytes, dermal vascular endothelial cells, and keratino cytes. Infiltrating mononuclear cells stained positively for CD4 or CD8, wi th CD4(+) cells always being in the majority. Surprisingly, most of the CD4 + cells had histiocytic, rather than lymphocytic, morphologic characteristi cs. Immunostaining for CD14 confirmed that these cells were monocytic in or igin, whereas immunostaining for CD3 revealed that the lymphocytes were pre dominantly CD8(+) cytotoxic T cells. B cells were not detected despite the presence of variable numbers of plasma cells in all specimens. By immunoflu orescence, all of the specimens demonstrated perivascular deposition of imm unoglobulins, complement, or fibrinogen; linear staining at the dermal-epid ermal junction also was observed in most of the specimens. No differences i n immunocytochemical or immunofluorescence staining patterns were observed between the specimens from patients who were HIV positive and patients who were HIV negative. In addition to providing a more precise definition of th e infiltrating cells ia syphilitic lesions, our results, taken as a whole, indicate that cellular immune processes are largely responsible for the dev elopment of cutaneous manifestations during syphilitic infection and that c oinfection with HIV-1 has little discernible effect on the cutaneous respon se to T. pallidum.