Introduction: Studies of incidental IgAGD have been mostly reported from the eastern hemisphere where IgA nephropathy is common. The incidence and significance of incidental IgAGD in donor kidneys in North American populations is not widely reported. We examined the frequency, clinical significance and histological fate of incidental IgAGD in an ethnically diverse population the southern USA.
Methods: All time-zero biopsies of kidneys transplanted from 2009-2016 were reviewed for the presence of IgAGD identified by direct immunofluorescence. Subsequent biopsies of recipients of kidneys with incidental IgAGD were examined for the fate of the deposits. Clinical data was obtained and two tailed T test was used to compare categorical variables. Kaplan Meier (KM) analysis was used to analyze patient and graft survival.
Results: Of 958 time-zero biopsies, 94 biopsies (9.8%; age 43 ±14 yrs , range of 10-70; 10% African American, and majority Caucasian ) had mesangial IgA deposits  (12.5% in deceased donor kidneys and 4.62% in living donor kidneys). Donors with IgAGD were older 44 vs 37yrs (p = 0.001), had more HTN (24.7% vs. 13.4 %, p = 0.002), and DM (12.3% vs 5.7%, p = 0.022). Thirty six IgA +ve biopsies (38%) had associated glomerulosclerosis with 8 showing ≥ 16% glomerulosclerosis .Mild interstitial fibrosis and tubular atrophy involving 10-15% of the cortical area and Arterial sclerosis were noted in 31and 25 biopsies respectively.
43 recipients of IgA +ve kidneys had a total of 58 subsequent biopsies of which 74% of the first year biopsies demonstrated resolution or significant decrease of IgAGD. Further clearance was noted in in the small number of second year biopsies. Overall biopsies with resolution were later (285 vs 125 days), had lower baseline intensity of IgA staining (1.63 vs 2.23) and had lower serum creatinine (2.2 vs 2.6). Kaplan Meier (KM) analysis at 5 years showed a patient/graft survival of 90%/88% in IgA positive recipients’ vs 88%/80% in recipients without IgAGD.
Conclusion: The incidence of incidental IgAGD in kidneys donated by an ethnically diverse population in the US is around 10%. Donor IgA has a benign prognosis post-transplant. The prevalence of IgAGD emphasizes the utility of time zero biopsies in differentiating donor IgAGD from recurrence of recipient IgA. Of concern is the finding of IgAGD in well screened living kidney donors, which should prompt longitudinal follow-up of these donors.