Transplant immunology II: overcoming acute and chronic rejection

Human leukocyte antigen (HLA) matching between donor and recipient for all six major histocompatibility antigens will minimize the immune activation of the recipient after solid-organ transplantation. Corticosteroids, the antiproliferative agents azathioprine and mycophenolate, calcineurin inhibitors cyclosporine and tacrolimus, antilymphocyte sera and rapamycin suppress different pathways of immune activation, although they have potential side-effects. Donor antigen-pretreatment of the recipient to induce graft acceptance and tolerance is difficult in renal transplantation, and impracticable for cardiothoracic transplantation. The stages leading to chronic obliterative bronchiolitis after lung transplantation are described. The role of cluster of differentiation-4+ (CD4+) T-cells, antigen-presenting cells and CD8+ T-cells in chronic rejection are also discussed. Different types of antigen are recognized through direct and indirect pathways.