Studies of sera from IgA nephropathy patients to explain high kidney graft survival

Posttransplant recurrence of primary glomerulonephritis

All forms of primary GN may recur after kidney transplantation and potentially jeopardize the survival of the graft. IgA nephritis (IgAN) may recur in approximately one third of patients, more frequently in younger patients and in those with a rapid progression of the original disease. However, with the exception of few patients with rapid progression, there is no evidence that recurrence of IgAN has a deleterious effect on graft survival at least up to 10 years. Recurrence of focal segmental glomerulosclerosis (FSGS) is often associated with nephrotic proteinuria and is more frequent in children, in patients with rapid progression of the original disease, and in those who lost a previous transplant from recurrence. The natural course of recurrent FSGS is usually unfavorable. Early and intensive plasmapheresis may obtain complete or partial response in several patients. Good results have also been reported with rituximab. Idiopathic membranous nephropathy (IMN) may recur in 30% to 40% of patients. The graft survival in patients with IMN is not different than that of patients with other renal diseases. Good results with rituximab have been reported. Membranoproliferative GN (MPGN) may recur in 27% to 65% of patients. The recurrence is more frequent and the prognosis is more severe in type II MPGN. Although recurrent GN is relatively frequent and may worsen the outcome of renal allografts in some patients, its effect is diluted by several other risk-factors that may have a greater effect than recurrent GN on the long-term graft survival.

Renal transplantation in patients with IgA mesangial glomerulonephritis

Most patients with IgA nephritis are suitable candidates for renal transplantation. In about 33% of patients the disease may recur after transplantation, although there are differences in the various series because of the different criteria for biopsy, the different length of follow-up and the different ethnicities. Living donation, genetic factors and time of progression of original disease have been found to be related with the risk of recurrence by some investigators, but these associations were not confirmed by other studies. The graft survival in patients with IgA nephritis is similar or even better than that observed with other renal diseases. The available data indicate that recurrence has a little impact on the 10-yr graft survival. However, a minority of patients may show a rapid progressive course after recurrence. Little information is available on the impact of recurrence in the very long term. There is no established treatment for preventing or treating the recurrence of IgA nephritis.

IgA class antibodies and flow cytometric cross-matching in renal transplantation

BACKGROUND

The established method of pretransplant cross-matching does not detect IgA antibodies, and IgA antibodies have thus been ignored when assessing patients for transplantation. The aim of this study was to detect IgA allo- and autoreactive antibodies using flow cytometry and to correlate the results with transplant outcome.

METHODS

Pretransplant sera from 231 sequential renal recipients were tested for serum IgA levels and antibodies directed against the Fab portion of the human IgG molecule. Fifty-nine recipients with sufficient stored donor lymphocytes were also tested by flow cytometry for donor-specific alloantibodies of the IgA isotype.

RESULTS

Graft survival was improved in recipients with higher IgA levels. High IgA anti-Fab levels led to a significantly higher 1-year graft survival (P<0.05). Graft survival was further enhanced where both serum IgA and IgA anti-Fab were raised (P<0.01). Although the mean IgA level tended to be higher for recipients with a positive IgA flow cytometric cross-match (FCXM), the IgA FCXM was not associated with increased IgA anti-Fab, suggesting that the IgA FCXM is detecting a different subset of IgA reactivity. Additionally, for primary grafts, a positive IgA FCXM was not associated with enhanced graft survival.

CONCLUSIONS

Within the repertoire of IgA activity, there are two recognizable groups, the IgA anti-Fab specificity, which is significantly associated with enhanced graft survival, and that detected by the IgA FCXM, which surprisingly is more likely to be positive in less sensitized first grafts and is not associated with enhanced graft survival.