Monoamine- and diamine oxidase activities in psoriasis

Monoamine- and diamine oxidase activities were measured by a sensitive photometric assay in 25 psoriasis vulgaris patients. Results were compared with plasma histamine values determined fluorimetrically. Increased plasma histamine levels were associated with significantly lowered diamine--and type B monoamine oxidase activities in platelet-rich plasma of the psoriasis patients. Our data suggest that cofactor levels and/or inhibiting factors are responsible for the observed monoamine- and diamine oxidase activities.