Rôle physiopathologique des anticorps catalytiques et des anticorps polyréactifs. (Physiopathological role of catalytic and polyreactive antibodies)

Renal transplant is the treatment of choice for patients with end-stage renal disease. We have previously identified low levels of catalytic IgG as a potential prognosis marker for chronic allograft rejection. The origin and physiopathological relevance of catalytic antibodies is not well understood owing to the fact that catalytic antibodies have been studied in relatively small cohorts of patients with rare diseases and/or without systematic follow-up. In the present study, we have followed the evolution of levels of catalytic IgG in a large cohort of renal transplant patients over a period of 2 years. Our results demonstrate that, prior to transplant, patients with renal failure present with heterogeneous levels of IgG hydrolyzing the generic PFR-MCA substrate. PFR-MCA hydrolysis was greater in the case of patientsÕ IgG than in that of a preparation of pooled IgG from healthy donors. Renal transplant was marked by a drastic decrease in levels of catalytic IgG over three months followed by a steady increase during the next 21 months. Patients who displayed high levels of catalytic IgG pre-transplant recovered high levels of catalytic antibodies 2 years post-transplant. Interestingly, IgG-mediated hydrolysis of a model protein substrate, pro-coagulant factor VIII, did not correlate with that of PFRMCA prior transplantation, while it did 24 months post-transplant. Taken together, our results suggest that the level of circulating catalytic IgG under pathological conditions is an intrinsic property of each individualÕs immune system, and that recovery of pretransplant levels of catalytic IgG is accompanied by changes in the repertoire of target