[Cellular mechanisms implicated in anti-erythrocyte alloimmunization]

In many clinical situations patients are dependent on blood transfusions. Occurrence of alloimmunization to blood group antigens (BGA) complicates the transfusion strategy and may be involved in clinical transfusion stalemate situations. B cell differentiation into antibody-secreting plasma cells is triggered by antigen and requires helper T cells which produce cytokines. Although antibodies implicated in BGA alloimmunization have been studied for many years, little is known about helper T cell responses that drive their production. Few studies on BGA specific T cell responses have been published today. This review summarizes the new developments in the field of cellular mechanisms implicated into antibody production. The definition of immunodominant peptides derived from RhD and Jk(a) BGAs, the cytokine patterns induced and the HLA class II molecules implicated in their presentation are analyzed. A tolerogenic route for RhD immunodominant peptides is experimented. Identification of such immunodominant peptides, the cytokine patterns induced and the HLA class II molecules implicated in their presentation, would facilitate the design of new therapeutic strategies including the specific control of alloimmunization with peptide antigen tolerogens or the ex-vivo induction of regulatory T cells.