CD28 and KIR2D receptors as sensors of the immune status in heart and liver transplantation

Viral infections and cellular acute rejection (AR) condition immunosuppressive therapy and compromise the evolution of allografts. Immune monitoring can be useful for ascertaining rejection and for differentiating allo-reaction from activation induced by infections. This work analyzes the usefulness of monitoring the expression of CD28 and KIR2D receptors in peripheral blood T lymphocytes by flow cytometry, to ascertain the immune response in heart and liver transplant recipients. In both types of transplant, the up-regulation of CD28 in CD4+ lymphocytes in the periods of greatest AR frequency indicates an effective allo-response, whereas the post-transplantation emergence of circulating CD8+CD28− and CD8+CD28−KIR2D+ T cells correlates with better early clinical results. Cytomegalovirus (CMV) infection, but not hepatitis C virus (HCV) or other infections, abrogated both CD28 up-regulation and CD8+CD28−KIR2D+ T-cell expansion. Our results show that monitoring the expression of CD28 and KIR2D receptors on T lymphocytes might be considered as sensors of the immune status of heart and liver recipients.