An antigenic determinant is shared by psoriasis-associated p27 antigen and the Fc part of human IgG

Rabbit antisera against the major internal protein, p27, of retrovirus-like particles from psoriatic urine, and against the serologically cross-reacting antigen, pso p27, from psoriatic scale, reacted with the Fc part of human IgG. Evidence indicating that the p27 antigen and the pso p27 antigen are identical has been presented in previous reports. A commercial antiserum against human IgG recognized a component in the pso p27-containing solution used as the source of antigen for immunization of the rabbits. By means of monoclonal antibodies against the pso p27 antigen, it was demonstrated that the Fc-reacting antibodies, and the antiserum against human IgG, recognized an epitope on the pso p27 antigen. The data indicated that an antigenic determinant is shared by the p27 antigen(s) and human IgG, suggesting that p27 antigen(s) may act as antigen(s) eliciting the production of antibodies with rheumatoid factor activity in psoriatic patients.