Donor's and recipient's antigen presenting cells co-operatively enhance the allo-reactive proliferation of peripheral blood lymphocytes

Abstract Antigen-presenting cells (APC) play important roles in the alloreactive proliferation of T cells in vitro and in the allo-graft rejection in vivo . This work was aimed at establishing whether a co-operation of any kind occurs between donor's and recipient's APC during alloreactions, and whether certain cell surface molecules, such as β 2 -microglobulin( β 2 m) and human leucocyte antigens (HLA), are involved in such an interaction. The data herein reported show that the alloreactive proliferation of peripheral blood lymphocytes (PBL) is markedly intensified by a positive co-operation between donor's and recipient's APC. Such a synergistic co-stimulatory action can be significantly hindered by a monoclonal antibody aimed against β 2 m while being not changed by monoclonal antibodies binding to either HLA-A-B-C or HLA-DR molecules. Hence, our preliminary results indicate that a positive interaction between donor's and recipient's APC may be of importance for allo-graft rejection.