HEPATOTOXICITY OF RICIN, SAPORIN OR A SAPORIN IMMUNOTOXIN - XANTHINE-OXIDASE ACTIVITY IN RAT-LIVER AND BLOOD-SERUM

Male Wistar rats each received an i.p. injection of the ribosome-inact ivating proteins ricin or saporin, or a Ber-H2 (anti-CD30)-saporin imm unotoxin at a dose corresponding to three times the LD(50) calculated for mice. Animals were killed 24, 48 or 72 h after treatment. Histolog ical examination showed hepatic necrosis in all treated animals, altho ugh the sinusoidal lining was affected only in ricin-poisoned rats. Th e activities of xanthine dehydrogenase (D-form) and oxidase (O-form) w ere determined spectrophotometrically in liver and serum samples. In r icin-treated animals the liver enzyme was progressively converted from the D- to the O-form, which accounted for more than 60% of total acti vity after 48 h of poisoning, whilst no change in the xanthine oxidase activity was found in the serum. In the liver of rats treated with fr ee or Ber-H2-conjugated saporin, the D-form was more than 75%, as in n ormal animals. In the same animals the serum xanthine oxidase activity was up to three-fold control values. The determination of serum xanth ine oxidase may prove helpful in the evaluation of liver damage in pat ients treated with immunotoxins. It may become a diagnostic tool for t he differential diagnosis of liver diseases.