Introduction

Recently, Todo et al. reported that ex-vivo generated immunomodulatory cells induced operational tolerance in 7/10 liver transplanted recipients. To allow wide spread application, it is crucial to address which cells are responsible for the donor-antigen specific immunomodulatory effects.

Methods

Immunomodulatory cells were generated by 14 days co-culture of recipient peripheral blood mononuclear cells (PBMCs) (50 x 10^6 cells) with irradiated HLA-mismatched donor PBMCs (20 x 10^6 cells) in presence of CTLA4-Ig (40 mg/10^6 recipient PBMCs). The generated cells were enriched for CD4+ CD25+ cells (Tregs) using MACS, or depleted of CD4+ or CD8+ (using MACS), CD19+, or CD25+CD127lo (using FACS). Suppressive functions of the non-sorted generated cells, and enriched or depleted cell-populations were measured in vitro: Freshly isolated recipient PBMCs were stimulated by irradiated donor or 3rd party PBMCs, with or without generated cells. Cell proliferation and cytokine production was compared.

Results

Non-sorted cells showed significantly stronger donor antigen-specific immunomodulatory effects compared to Treg enriched cells.

Treg or B-cell depleted generated cells showed immunomodulatory effects against both donor and 3rd party antigen.

Depletion of CD4+ or CD8+ cells maintained the donor-antigen specific inhibitory effects. IFN-γ was mainly produced by CD4+ cells. Depletion of B-cells or Tregs from the generated cells lower the production of IL-10.

Conclusion

The ex-vivo generated cells without any enrichment showed stronger donor antigen-specific immunomodulatory effect. The Tregs and B-cells seems to be important in generating the donor-specificity.

CITATION INFORMATION: Yao M., Kumagai-Braesch M., Watanabe M., Tokodai K., Lundgren T., Uhlin M., Ericzon B. Ex-Vivo Generation of Alloantigen-Specific Immunomodulatory Cells: Elucidating the Mechanistical Synergy of Cell Components Am J Transplant. 2017;17 (suppl 3).

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