Mycobacterial 65,000 MW Heat-Shock Protein Shares a Carboxy-Terminal Epitope with Human Epidermal Cytokeratin 1/2

The study demonstrated that mycobacterial heat-shock protein (hsp) 65 shared a carboxy-terminal epitope with human epidermal cytokeratin 1/2, suggesting a potential role in autoimmune skin diseases. Two monoclonal antibodies, Ne5 and Nd4, were found to cross-react with suprabasal cytokeratin in normal human skin, specifically staining the cytoplasm of epidermal keratinocytes but not HeLa cells or fibroblasts. Immunoblotting confirmed that these antibodies reacted with a 65,000-67,000 MW keratin protein, consistent with cytokeratin 1/2. The cross-reactivity was abolished by preincubation with purified mycobacterial hsp 65, indicating a shared epitope. This molecular mimicry might be significant in the pathogenesis of certain skin conditions.