CD40LG and Autoimmunity: Two studies have investigated the role of autoimmunity in islet allograft rejection.[50, 51] Makhlouf et al., compared the survival of islet transplants with cardiac transplants, the former subject to autoimmunity while the latter not, and found that in the presence of CD80/86 and CD40L blockade, MHC matching favored heart but not islet survival, while the absence of full or MHC class II matching resulted in no difference between the survival of the heart and the islet.[50] This indicates that autoimmunity played a significant role in islet allo‐rejection.