Fcγriib Expression on B Cells Is Associated with Treatment Efficacy for Acute Rejection after Kidney Transplantation

BACKGROUND: Fcγ receptors (FcγR) play a role in the acute rejection (AR) of organ transplants. FcγRIIB is an inhibitory FcγR expressed on B cells. Intravenous IgG (IVIG) and CD28 monoclonal antibody (mAb) have been shown to have immunomodulatory properties against AR. AIM: To examine the association between FcγRIIB expression on B cell subpopulations and AR treatment efficacy. METHODS: Male F344 rats were used as kidney donors and Lewis rats as recipients to establish models of renal transplantation. Rats were divided into five groups: sham, AR-PBS, AR-IVIG, AR-PNGase F-IVIG, and AR-CD28. Serum creatinine (Scr), blood urea nitrogen (BUN), and urine protein content were determined. Inflammatory markers were measured by ELISA, FcγR by western blotting, and spleen B cell activation by flow cytometry. RESULTS: Scr, BUN, urinary protein content, levels of CRP, IL-10, TNF-α, IL-6, IL-8, and IgG were all increased in the AR-PBS group compared with the sham group (all P<0.01); these increases were partly reversed in the AR-IVIG, AR-PNGase F IVIG, and AR-CD28 groups (all P<0.01), with IVIG showing the better efficacy than PNGase F IVIG. Furthermore, blood and spleen FcγRIA and FcγRIIIA were increased by AR, while FcγRIIB expressions in splenic activated B cells and regulatory B cells were decreased; these changes were partly alleviated by all three treatments, with IVIG having the better effect than PNGase F IVIG. CONCLUSION: We observed an association between B cell FcγRIIB expression and treatment efficacy for AR after kidney transplantation in rats.