Promotion of corneal allograft survival by the induction of oxidative macrophages.

Abstract

A Th1-type immune response was detected in allotransplanted, rejected corneas. Because the intracellular thiol redox status of antigen-presenting cells (APCs) reportedly regulates the Th1/Th2 balance through distinctive cytokine production by APCs, this study was conducted to investigate the effect of the intracellular thiol redox status of macrophages (Mps) on corneal allograft survival. N,N'-diacetyl-L-cystine dimethylester (NACOMe)(2) was injected intraperitoneally into BALB/c (H-2(d)) mice to induce Mps with a low intracellular glutathione content (icGSH). Corneal grafts from C57BL/10 (H-2(b)), B10.D2 (H-2(d)), and DBA/2 (H-2(d)) donor mice were placed on neovascularized BALB/c graft beds for assessment. B10.D2-grafted recipients were evaluated for donor-specific delayed-type hypersensitivity (DTH), and the cytokines produced by their lymphocytes were examined (IFN-gamma, IL-4, and IL-10). In other experiments, naïve BALB/c mice, injected intravenously with Mps of low icGSH content, received B10.D2 corneal grafts. In (NACOMe)(2)-treated mice, 13 of 20 B10.D2 grafts and 6 of 10 DBA/2 grafts survived indefinitely. No grafts survived in the control mice (P < 0.0001). (NACOMe)(2) treatment did not enhance C57BL/10 graft survival. At 2 weeks after B10.D2 grafting, control mice exhibited DTH, but (NACOMe)(2)-treated mice did not (P < 0.01). Lymphocytes from (NACOMe)(2)-treated mice did not respond to donor splenocytes. Those of control mice showed Th1-type cytokine secretion. The intravenous transfer of peritoneal Mps from (NACOMe)(2)-treated mice prolonged corneal allograft survival (P < 0.003). The observed enhanced graft acceptance may be due to the suppression of alloantigen-induced Th1 polarization through the induction of Mps with reduced icGSH levels.