Until recently, the vigorous T-cell response via the direct pathway has overshadowed
studies involving the indirect pathway. Thus, while the direct pathway has previously been
considered to be the main driving force in alloimmune responses, there is an increasing
body of data to support a prominent role of the indirect pathway in transplant rejection. Most
importantly, the direct antidonor alloresponse diminishes with time after transplantation,
possibly due to the tolerogenic effects of alloantigen presentation by the parenchymal cells …