Combined standard and novel immunosuppressive substances affect B-lymphocyte function

A considerable fraction of renal transplanted patients is susceptible to humoral rejection. Today well-established therapy regimens are available to control antibody-mediated rejection in the short term. Nevertheless, donor-specific antibodies persist and graft function deteriorates over time. This might be due to insufficient maintenance immunosuppression — which always consists of two to three drugs with different mechanisms of action. Since T- and B-cell functions always depend on each other in the alloimmune response it is of interest to analyze the effects of combined standard and new immunosuppressive substances with T-cell inhibitory properties on B-cell function. The effectiveness of complementary administrations of sotrastaurin, mycophenolic acid and everolimus on the activation and function of human primary B-lymphocytes was tested. Everolimus and mycophenolic acid alone and in combination proved to be highly effective in suppressing B-cell activation, whereas the proteinkinase C inhibitor sotrastaurin had an unexpected and reverse impact on various B-cell functions when applied in combination with the mammalian target of rapamycin and the inosine monophosphate dehydrogenase inhibitor.