T Cell Stimulating Stratum Corneum Antigens: Characterization by Chromatography and Electrophoresis Indicates Limited Diversity

Abstract

As part of a search for T cell autoantigens in inflammatory skin diseases, we have demonstrated proteinase K sensitive, denaturation stable, T cell stimulatory material with antigenic properties in aqueous extracts of stratum corneum from normal human skin. Activity was also demonstrable in extracts of whole epidermis. A combination of preparative, analytical, and microbore reversed phase high performance liquid chromatography, chromatofocusing, and denaturing preparative sodium dodecylsulfate-polyacrylamide gel electrophoresis indicated limited structural diversity. Five components were separated, with Mr values from 5 to 18 kDa and apparent PI values from 4.5 to 10. Three components were purified to near homogeneity and showed molecular weights of 5, 13.5, and 18 kDa. Their potency was shown by the ability to induce stimulation indices of 20-89 with peripheral blood mononuclear cells and >500 with T cell lines. Use of inhibitors indicated that the active materials were not generated by the in vitro actions of proteases during extraction. The five partially purified components induced a time course of peripheral blood mononuclear cell proliferation compatible with the effects of antigen rather than superantigen. The 5 kDa component was rigorously bulk purified to yield a fraction that induced potent T cell activation but contained minimal detectable protein, a further indication of its biologic potency. Normal stratum corneum thus contains previously undescribed T cell antigens of high potency but limited structural diversity. The present data form a basis for determining their structure, cellular origin, and pathogenic relevance.