The major internal protein, p27, of a retrovirus-like particle participates in immune complex formation in psoriasis.

The major internal protein, p27, of a retrovirus-like particle isolated from the urine of a patient with psoriasis has been purified and used in an indirect ELISA to detect human antibodies against the virus antigen. Rabbit anti-p27 antiserum has been applied to detect p27 antigen present in clinical specimens. p27 and anti-p27 antibodies have been demonstrated in extracts from psoriatic scales. Insignificant amounts of free anti-p27 antibodies are present in serum, but both p27 and anti-p27 antibodies have been detected in circulating immune complexes obtained from serum or synovial fluid from patients with psoriatic arthritis.