In Vitro Model of Suppression of the Alloantigen Response by Tolerogenic Dendritic Cells Transfected with Personalized DNA Constructs Encoding HLA Epitopes

Abstract

Background: A search for efficient graft rejection modulation techniques for the promotion of durable engraftment remains to be a matter of close study all over the world. Despite the variety of immunosuppressive drugs, the schemes currently used show a lack of selectivity and have a number of side effects. Here we investigated an approach for the induction of antigen-specific tolerance in a human "stimulator-responder" model in vitro, using dendritic cells (DCs) transfected with designed DNA constructs encoding the stimulator's major histocompatibility complex (MHC) epitopes.

Methods: The object of the study is peripheral blood mononuclear cells (PBMCs) from 10 healthy donors. To induce antigen-specific tolerance, personalized DNA constructs were created for five responder-stimulator pairs, based on the sequences of donors' and recipients' MHCs. DNA sequencing was performed to select epitopes for incorporation into genetic constructs. A mixed lymphocyte culture assay was used (i) to assess the proliferative response in both directions for all possible stimulator-responder pairs (90 reactions) and (ii) to assess the tolerogenic properties of the generated transfected DCs (5 reactions).

Results: A significant increase in the amounts of FoxP3+ CD4+CD25+ cells and in IL-10 production was shown in culture of donor mononuclear cells after co-cultivation with the responder's dendritic cells transfected with donor-specific plasmids. The tolerogenic cultures generated using tolerogenic DCs transfected with MHC epitopes had a significantly greater ability to inhibit the proliferation of autologous MNCs in response to an allogeneic MHC stimulus.

Conclusions: The produced DCs transfected with DNA constructs against HLA stimulating epitopes exhibited tolerogenic properties and may be used to develop antigen-specific tolerance. Thus, we proposed a perspective approach to the induction of antigen-specific tolerance, which should subsequently be studied for use in clinical practice.

Keywords: DNA constructs; HLA; MHC; T regulatory cells; alloantigens; mediated immune suppression; mixed lymphocyte culture; tolerogenic dendritic cells.