Increased serum levels of the pregnancy zone protein in psoriasis.

On the basis of immunological studies on psoriasis in recent years, it seems probable that immunological mechanisms are of importance and that psoriasis could be regarded as an immunogenetic disease. In this study, increased serum levels of an immunosuppressive factor, the pregnancy zone protein (PZ), were found in psoriatic patients. Patients with elevated levels (greater than 2 S.D. units) of PZ showed a positive association with continuous symptoms and a negative association with blood groups A and Fy(a+b-). Thus, induction of PZ occurs mainly in psoriatic patients who have a particular genetic constitution. The results support the hypothesis that PZ is not only an immunosuppressive but also an immunoreactive protein.