ANALYSIS OF CYTOKINES AND ANTI-HLA ANTIBODIES IN KIDNEY TRANSPLANTATION: TRANSFORMING GROWTH FACTOR-BETA1 EXHIBITED A PROTECTIVE EFFECT ON CHRONIC REJECTION.

Abstract

P995 Aims: Chronic rejection (CR) is the most important problem to be overcome in modern transplantation medicine. This study was designed to elucidate which cytokine (IL-2, IFN-γ, IL-4, IL-10, or TGF-β1) and what type of antibodies (anti-HLA class I or II, IgM or IgG) is associated with the progress of CR of kidney allografts. Methods: Peripheral blood serum was isolated from kidney allograft recipients at the episode of CR (37 cases, CR group) and from those without rejection (40 cases, NR group). Serum concentrations of IL-2, IFN-γ, IL-4, IL-10, and TGF-β1 were measured using the commercial ELISA kits (Biosource Inc.). Anti-HLA class I and class II antibodies were detected by reacting the serum with FlowPRA class I and class II beads, respectively (One Lamda Inc.). Antibodies of IgG and IgM immunoglobulin classes were detected by flowcytometry using FITC-conjugated second antibodies against each human immunoglobulin class. The degree of HLA compatibility between recipients and donors were estimated using the MatchMaker program (Duquesnoy). Results: No significant difference was detected between the CR and NR groups in the serum levels of IL-2, IFN-γ, IL-4, or IL-10. On the other hand, serum level of TGF-β1 of the CR group was significantly lower than that of the NR group (p<0.006 in both t-test and Mann-Whitney test). Furthermore, TGF-β1, but none of other cytokines, exhibited weakly but significantly negative correlation with the serum creatinine level (r=-0.24, p<0.05). These results suggested that TGF-β1 served as a protective factor against CR, contrasting to the several reports revealing the CR-promoting effect of this cytokine. Our results would stress the immunosuppressive and anti-inflammatory activity rather than the fibrosis-inducing activity of TGF-β1. In the analysis of anti-HLA antibodies, only anti-HLA class I IgM antibody in the CR group exhibited a significant correlation with the degree of HLA mismatches (r=0.59, p<0.01 against class II mismatches; r=0.68, p<0.01 against class I+II mismatches). However, no significant difference was detected between the CR and NR groups in any type of anti-HLA antibodies (anti-class I or II, IgM or IgG). None of anti-HLA antibody types showed significant correlation with the serum creatinine level. Further follow up of the patients is continued to elucidate the role of anti-HLA antibodies in the progress of CR. Conclusions: CR was associated with the low serum level of TGF-β1. The contribution of anti-HLA antibodies to CR was not confirmed.