Humoral immunity after kidney transplantation: impact of two randomized immunosuppressive protocols

Controlling alloimmune humoral response is a challenge in transplantation. Few studies have evaluated the impact of maintenance immunosuppression on blood humoral parameters.

We performed a post-hoc analysis on 307 kidney transplant recipients included in a prospective randomized trial comparing tacrolimus/mycophenolate mofetil (Tac/MMF) vs. cyclosporine/azathioprine (CsA/AZA), both used with antithymocyte globulin induction and steroids. Humoral parameters were analyzed at D0, D15, and M12.

IgG, IgA, and IgM levels decreased significantly as soon as D15 in both groups (–35%, –26%, and –35% respectively, vs. D0). At M12, although peripheral B-cell counts did not differ between the groups, Tac/MMF regimen was associated with lower IgG, IgA, and IgM levels than CsA/AZA (–5.9%, –14.6%, and –34%, respectively). Hypogammaglobulinemia at D15 was not associated with an increased risk of infections during the first year. The proportion of HLA-sensitized patients decreased in the Tac/MMF group (15.9% at D0 and 6.7% at M12, p=0.02) and remained stable in the CsA/AZA group (10.3% at D0 and 8.9% at M12, p=0.5). More patients sensitized at baseline became non-sensitized at M12 with Tac/MMF than with CsA/AZA.

Our results suggest humoral immunosuppression is better with Tac/MMF than with CsA/AZA during the first year of kidney transplantation.