Depletion of alloreactive T cells via CD69: implications on antiviral, antileukemic and immunoregulatory T lymphocytes

Abstract

Selective depletion of alloreactive T cells from stem-cell allografts should abrogate graft-versus-host disease while preserving beneficial T cell specificities to facilitate engraftment and immune reconstitution. We therefore explored a refined immunomagnetic separation strategy to effectively deplete alloreactive donor lymphocytes expressing the activation antigen CD69 upon stimulation, and examined the retainment of antiviral, antileukemic, and immunoregulatory T cells. In addition to the CD69 high T cell fraction, our studies retrieved two T cell subsets based on residual CD69 expression. Whereas, truly CD69 neg cells were devoid of detectable alloresponses to original stimulators, CD69-low (CD69 low )-expressing T cells elicited significant residual alloreactivity upon restimulation. In interferon-c enzyme linked immunospot assays, anti-cytomegalovirus and anti-Epstein-Barr virus responses were preserved at significant numbers among CD69 neg T lymphocytes. Accordingly, T cells recognizing the leukemia-associated Wilm's tumor-1 antigen were still detectable in the CD69 neg subset. However, antiviral and antileukemic specificities were also consistently found within CD69 low T cells, suggesting that memory-type donor T cells were partially captured due to residual CD69 expression. Finally, CD4 þ CD25 þ Foxp3 þ immunoregulatory T cells did not upregulate CD69 upon allogeneic stimulation. Our data suggest that CD69-mediated removal of alloreactivity can result in efficient allodepletion, but may partially affect the persistence of antiviral and antileukemic donor memory specificities captured among CD69 low -expressing lymphocytes.

Isolation of human antigen‐specific regulatory T cells with high suppressive function

“…CD69 is not an appropriate marker for specifically activated Treg cells as it can also be increased by cytokines in a bystander fashion [30]. In addition, both markers are not specifically expressed on Treg cells.…”

“…Sagoo et al suggested that the upregulation of CD69/CD71 on Treg cells after an allogeneic activation can be used for the isolation of Ag-specific Treg cells [29]. CD69 is not an appropriate marker for specifically activated Treg cells as it can also be increased by cytokines in a bystander fashion [30]. In addition, both markers are not specifically expressed on Treg cells.…”

Haploidentical hematopoietic transplantation: current status and future perspectives

“…T-cell preparations are purged of alloreactive donor T cells by activation in mixed lymphocyte reaction against host stimulators, followed by depletion with immunotoxins, immunomagnetic selection, or FACS, all of which exploit expression of cell surface activation markers (CD25, CD69, CD134, CD137, CD147, and HLA-DR). [59][60][61][62][63] Other methods include FasL-mediated killing of activated T cells, 64 apoptosis induction by heat shock protein 90 (HSP 90), 65 or anergy induction by costimulatory blockade. 66 The anti-CD25 antibody conjugated to ricin toxin was first used in pediatric patients with immune deficiencies.…”

Expression of a dominant T-cell receptor can reduce toxicity and enhance tumor protection of allogeneic T-cell therapy

“…18 Various approaches have been developed, including the transfer of purified memory T cells 19,20 or the in vitro depletion of allo-reactive T cells stimulated with recipient antigen-presenting cells. [21][22][23] Similarly, in vitro stimulation of allo-reactive T cells in the presence of co-stimulation blockade was used to induce T-cell anergy. 24 An elegant alternative to the in vitro depletion of allo-reactive T cells is the introduction of 'suicide genes' that can be triggered in vivo in patients developing GvHD after T-cell transfer.…”