Ex vivo generation of human alloantigen-specific regulatory T cells from CD4posCD25high T cells for immunotherapy

Abstract

Background: Regulatory T cell (Treg) based immunotheraphy is a potential treatment for several immune disorders. By now, this approach proved successful in preclinical animal transplantation and auto-immunity models. In these models the success of Treg based immunotheraphy crucially depends on the antigen-specificity of the infused Treg population. For the human setting, information is lacking on how to generate Treg with direct antigen-specificity ex vivo to be used for immunotheraphy. Methodology/Principle Findings: Here, we demonstrate that in as little as two stimulation cycles HLA mismatched allogeneic stimulator cells and T cell growth factors a very high degree of alloantigen-specificity was reached in magnetic bead isolated human CD4pos CD25high Treg. Efficient increases in cell numbers were obtained. Primary allogeneic stimulation appeared a prerequisite in the generation of alloantigen-specific Treg, while secondary allogeneic of polyclonal stimulation with anti-CD3 plus anti-CD28 monoclonal antibodies enriched alloantigen-specificiy and cell yield to a similar extent. Conclusions/Significance: The ex vivo expansion protocol that we describe will very likely increase the success of clinical Treg-based immunotheraphy, and will help to induce tolerance to selected antigens, while minimizing general immune suppression. This approach is of particular interest for recipients of HLA mismatches transplants. © 2008 Peters et al.