Since MZ heterozygotes are almost always, and MS phenotypes sometimes, associated with decreased serum alpha 1-AT levels, and since Z and MZ phenotypes are associated with increased hepatic fibrosis or cirrhosis, these variants may be relevant to problems of spontaneous fibrosis or methotrexate-induced hepatotoxicity in psoriasis. alpha 1-AT deficiency may also contribute to guttate flares with infection and to increased O-2 . production by psoriatic sera-stimulated polymorphonuclear leukocytes (PMNs).