Transplantation 50 years later--progress, challenges, and promises

Infectious complications in organ transplant recipients with the use of calcineurin-inhibitor agent-based immunosuppressive regimens

PURPOSE OF REVIEW

The rates and types of infections associated with conventional immunosuppression regimens comprising calcineurin-inhibitor agents, tacrolimus, and cyclosporine could be used to compare similar data with the use of novel immunosuppressive regimens in organ transplant recipients.

RECENT FINDINGS

Tacrolimus appears to be superior to cyclosporine in preventing rejection. The frequency and spectrum of infections in organ transplant recipients does not appear to be notably modified by the choice of calcineurin-inhibitor agents per se. A higher risk of cytomegalovirus and poorer outcomes associated with hepatitis C virus with cyclosporine in some studies may be related to a greater requirement of adjunctive immunosuppression with cyclosporine-based regimens. Potent immunosuppression with tacrolimus, however, particularly when combined with mycophenolate mofetil, is believed to be a significant contributor to a higher incidence of BK virus nephropathy in renal transplant recipients in recent years. Calcineurin-inhibitor agents possess in-vitro activity against a number of fungal pathogens. In the clinical setting, however, the immunosuppressive effect outweighs their antifungal activity.

SUMMARY

Calcineurin inhibitor-based regimens have been the mainstay of immunosuppression after organ transplantation for almost two decades. However, suboptimal long-term outcomes in transplant recipients have led to a growing interest in the use of calcineurin inhibitor agent-sparing regimens. Whether novel immunosuppressive agents with a more selective mechanism of action would lead to a further reduction in the risk of posttransplant infections remains to be discerned.

Design of effective immunotherapy for human autoimmunity

A better understanding of the molecules involved in immune responses has identified many potential targets for the treatment of autoimmune diseases. But although successful therapies have been found for immune disorders in animal studies, few have passed the much harder test of treating human diseases. So far, non-antigen-specific approaches, such as the blocking of tumour-necrosis factor, are achieving some success but the same is not true for antigen-specific approaches. Future therapies will probably include both non-antigen-specific strategies that target cytokines (cell-cell signalling molecules) or block the molecules that stimulate immune responses, and antigen-specific therapies that induce tolerance to self antigens.