Immune characteristics of renal allograft donors with mesangial IgA deposition

•Our data showed that 26% blood-related donors had mesangial IgA deposition.•IgA deposited in healthy donors contains galactose-deficient IgA1.•Levels of serum IgG anti-glycan antibodies in donors with IgA deposition were between healthy control and patients with IgAN. There are few studies describing the prevalence and immune features of people with subclinical mesangial immunoglobulin A (IgA) deposition in the Chinese population. We sought to investigate the prevalence of mesangial IgA deposition among kidney donors and the immune characteristics of donors with mesangial IgA deposition. Fifty blood-related living donors with zero-hour allograft biopsies obtained at Peking University First Hospital were enrolled. Galactose-deficient IgA1 (Gd-IgA1) in glomerular deposits was examined by double immunofluorescent staining using the specific monoclonal antibody KM55. Plasma IgA, IgA1, Gd-IgA1 and antibodies directed against Gd-IgA1 were measured using enzyme-linked immunosorbent assay. Thirteen of 50 (26%) donors had mesangial IgA deposition, which was confirmed by both immunofluorescence and electron microscopy. The levels of plasma IgA, IgA1 and Gd-IgA1 were all increased in donors with IgA deposition compared with those without IgA deposition (mean ± SD, 3.54 ± 0.505 versus 2.356 ± 0.265 mg/ml, p = 0.049; 3.003 ± 0.4048 versus 2.356 ± 0.265 mg/ml, p = 0.057; and 4.719 ± 0.4357 versus 3.356 ± 0.4707 ug/ml, p = 0.0440, respectively). Colocalized IgA1 and Gd-IgA1 indicated that there were galactose-deficient IgA1 deposits in the glomerular mesangium. While donors with IgA deposition showed lower levels of IgG anti-glycan antibodies than patients with IgA nephropathy (37.71 ± 8.886 versus 78.86 ± 5.155 units/ml, p = 0.001). The immune features of donors with IgA deposition, including IgA1 and Gd-IgA1 deposition, were similar to those of patients with IgA nephropathy, but donors with IgA deposition had lower levels of antiglycan antibodies, which may explain the subclinical status of IgA deposition in donors. Mesangial IgA deposition was common in the Chinese blood related donors cohort, further large study with both living and cadaveric donor kidneys was still needed to confirm these findings.