Antiviral immunity and T-regulatory cell function are retained after selective alloreactive T-cell depletion in both the HLA-identical and HLA-mismatched settings

CMV CTLs are retained after CD69⁺-based selective allodepletion. a, HLA-A2 CMV AE42 (NLV) peptide tetramer-binding CD3⁺ cells in an unmanipulated donor cell pool. b, HLA-A2 CMV AE42 (NLV) peptide tetramer-binding CD3⁺ cells in an HLA-matched selectively allodepleted fraction with OKT3-stimulated MLR. c, HLA-A2 CMV AE42 (NLV) peptide tetramer-binding CD3⁺ cells in an HLA-matched selectively allodepleted fraction with cytokine-stimulated MLR. (This figure show dot plots from a representative experiment.)

Functional CMV CTLs are retained after CD69⁺-based selective allodepletion. Retention of CMV CTLs by HLA-A2 CMV AE42 (NLV) peptide tetramer and retention of functional CMV CTLs by CMV peptide-stimulated IFN-γ ELISpot after selective allodepletion expressed as a percentage of the of value seen in unmanipulated cells.

CD4⁺ CD25⁺ T-regulatory cells are not removed by CD69⁺ selective allodepletion. Allostimulation in the OKT3-stimulated MLR in HLA-matched samples leads to an appearance of both CD69⁺ CD25⁻ and CD69⁺ CD25⁺ alloreactive CD3⁺ CD4⁺ T cells, which are removed by selective allodepletion based on CD69 expression. T-regulatory cells (CD4⁺ CD25⁺ CD69⁻) are not removed by this process. A, Allostimulated responder cells; B, untreated responder cells; C, selectively allodepleted responder cells.

CD4⁺ CD25⁺ T-regulatory cells present in selectively allodepleted cells retain immunosuppressive function. Proliferative responses to first-party stimulators in HLA-mismatched allogeneic MLRs is significantly reduced after the addition of CD4⁺ CD25⁺ T-regulatory cells (autologous to the responders) from selectively allodepleted cell fractions, whereas proliferation is not significantly affected after the addition of the CD4⁺ CD25⁺ T-regulatory cell negative fraction from selectively allodepleted cell fractions.