Latent IgA deposition from donor kidney is the major risk factor for recurrent IgA nephropathy in renal transplantation.

Background: Previous studies have recognized risk factors for recurrent IgA nephropathy (r-IgAN) in renal transplantation. However the clinical significance of latent IgA deposition from the donor kidney remains to be determined.

Patients And Methods: Between 1992 and 1999, 0-hour allograft biopsies were performed in 510 renal transplantation recipients at the Kidney Center of Tokyo Women's Medical University. Among these 510 patients, there were 49 whose primary disease was identified as IgAN. Among these 49 patients, 13 patients (26.5%) were diagnosed as having r-IgAN based on renal biopsy. We compared risk factors of r-IgAN, including IgA deposition, between the r-IgAN and non-r-IgAN groups.

Results: We assessed factors previously reported to be risk factors for r-IgAN, such as follow-up period after transplantation, sex, ages of donors and recipients, donor type, ABO compatible or incompatible transplantation, number of HLA-A, B, and DR mismatches, number of donors with HLA-A2, B35, B46, and/or DR4, duration to end stage renal disease, duration of dialysis, and latent IgA deposition from donor kidneys. Latent IgA deposition was the only risk factor that differed significantly in frequency between patients with and without recurrence (38.5% in r-IgAN group vs. 9.1% in non-r-IgAN group, p = 0.037). Other factors did not differ significantly between the two groups. Clinical factors, such as urinary protein excretion, urinary red blood cell sediment and serum creatinine, were significantly worse and the number of patients who required hemodialysis 5 yr after transplantation was significantly higher in the r-IgAN group than in the non-r-IgAN group (38.5 vs. 5.6%, p = 0.001). Four of the five patients who required hemodialysis in the r-IgAN group had latent IgA deposition from the donor kidney.

Conclusion: Our data suggest that 26.5% out of patients with primary IgAN will develop recurrence within 5 yr after transplantation. Latent IgA deposition from the donor kidney was one of the risk factors of r-IgAN and it would lead to the development of r-IgAN. Moreover, r-IgAN will compromise graft survival, especially in cases with latent IgA deposition from the donor kidney.