Immunosuppression regimens to address alloantibodies in transplant recipients

The purpose of immunosuppression in patients receiving a solid organ transplant is to prevent both acute and chronic rejection, while avoiding the complications of immunodeficiency such as infections and malignancy. Over the last 50 years, immunosuppressive agents have been developed and put into clinical practice to achieve this purpose. The majority of immunosuppressive agents developed during this time have focused on suppressing the T cells. T cell centric immunosuppressive development was a result of the early belief that the T cell caused an allograft to fail. However, emerging evidence from the use of new laboratory techniques has caused the field to reexamine this T cell centric view and focus on the role of the B cells. Today, humoral immunity is thought to be the major cause of allograft loss. As a result, newer immunosuppressive agents are being introduced to deplete the B cell populations in a patient's immune system. However, not all patients may need these immunosuppressive agents. It is only when patients are at high risk for donor specific anti-HLA antibody (DSA) development or when DSAs are present that these immunosuppressive agents may be necessary. This review will focus on the new agents and immunosuppressive regimens that may serve the high-risk subpopulations of solid organ transplant recipients who have or who develop DSA.