Pilot Study of Rituximab Treatment to Inhibit HLA Antibodies in Renal Allograft Recipients

A long established risk factor for late renal allograft loss is the development of DSA. Recent studies from our group and others have shown that these antibodies are probably responsible for chronic rejection by attacking the vascular endothelium and fixing complement (detected as C4d in renal biopsies). Studies in humans and monkeys have shown that circulating antibody and complement deposition precede the development of chronic graft injury. Interruption of antibody production is a potential beneficial strategy to prevent late graft loss from this mechanism.

Therapeutic regimens that have been used in an attempt to deplete HLA or ABO antibodies include plasmapheresis, IVIg, tacrolimus and mycophenolate mofetil (MMF), and anti-CD20 (rituximab). Of these regimens, the most specific is anti-CD20, rituximab (rituxan), a therapy now FDA approved for B cell proliferative diseases. Although initially introduced for the treatment of neoplasm, the humoral immunosuppressant effects of rituximab have been shown to have clinical significance. Rituximab interferes with both primary and secondary humoral responses by eliminating B-cells prior to antigen exposure, thus interfering with differentiation into antibody secreting cells and specific antibody production.