Inflammatory properties of IgG modified by oxygen radicals and peroxynitrite.

In inflammatory arthritis, there is evidence indicating that the affected tissues produce large amounts of oxygen-free radicals and NO. Herein, we examine the biologic effects of exposure of IgG to hypochlorous acid (HOCl) and peroxynitrite (ONOO). The concentrations of IgG modified by chlorination and nitrosation were measured in synovial fluids from inflammatory and noninflammatory arthritis. Human IgG was exposed to increasing concentrations of HOCl and ONOO, and the resulting products were tested for complement component binding; binding to FcgammaRI; activation of polymorphonuclear neutrophils; effect on the Ab-combining site of Abs; and in vivo inflammatory activity in a rabbit model of acute arthritis. Rheumatoid synovial fluids contained significantly greater concentrations of nitrosated and chlorinated IgG compared with ostearthritic specimens. In vitro exposure of human IgG to HOCl and ONOO resulted in a concentration-dependent decrease in C3 and C1q fixation. The decrease in Fc domain-dependent biologic functions was confirmed by competitive binding studies to the FcgammaRI of U937 cells. HOCl-treated IgG monomer was 10 times less effective in competing for binding compared with native IgG, and ONOO-treated IgG was 2.5 times less effective. The modified IgGs were also ineffective in inducing synthesis of H(2)O(2) by human PMN. The Ag-binding domains of IgG also showed a concentration-dependent decrease in binding to Ag. The ability of the modified IgGs to induce acute inflammation in rabbit knees decreased 20-fold as gauged by the intensity of the inflammatory cell exudates. These studies clarify the modulating role of biological oxidants in inflammatory processes in which Ag-autoantibody reactions and immune complex pathogenesis may play an important role.

[The determination of 210Pb in lead (author's transl)].

Since lead contains more or less 210Pb, the selection for lead materials has to be done before construction of the low level radiation shield. In this paper, a method for determination of 210Pb is based on radioanalytical separation such as DDTC (sodium diethyl dithio carbamate) extraction followed by beta ray counting of 210Bi. Fourteen commercial lead samples and three old lead samples were analysed for 210Pb. The concentration for 210Pb in commercial samples was found to range from 0.063 to 11 Bq/g (1.7 to 300 pCi/g) and in old samples was less than 0.01 Bq/g (0.3 pCi/g). These results will be useful to the selection of shielding material. The detection limit and the time required for 210Pb determination was 0.003 Bq/g (0.1 pCi/g) and 5.5 hours, respectively.