Regulatory T-cell depletion does not prevent emergence of new CD25⁺ FOXP3⁺ lymphocytes after antigen stimulation in culture

Abstract

Background

The removal of human regulatory T (T_reg) cells from a cellular product prior to the induction of a T-cell response has the potential to boost the total yield of antigen (Ag)-specific CD4⁺ and CD8⁺ T cells.

Methods

We examined the effect of this manipulation on the generation of human anti-cytomegalovirus (CMV) T-cell responses. Furthermore, we examined the clonotypic composition of Ag-specific CD4⁺FOXP3⁺ and CD4⁺FOXP3⁻ T cells.

Results

We found that the immunomagnetic depletion of CD25⁺ cells had an unpredictable effect on outcome, with total yields of CMV-specific T cells either increasing or decreasing after the removal of these cells. The depletion of CD25⁺ cells both removed a proportion of Ag-specific T cells and failed to eliminate a substantial population of T_reg cells. Furthermore, using a novel T-cell receptor clonotyping technique, we found that Ag recognition induces the expression of FOXP3 in a proportion of specific T cells; these FOXP3-expressing Ag-specific CD4⁺ and CD8⁺ T cells were no longer capable of producing inflammatory cytokines.

Discussion

The depletion of CD25⁺ cells from the starting population has a variable effect on the total yield of Ag-specific T cells, a proportion of which invariably acquire FOXP3 expression and lose effector function.

• CD25 depletion
• cytomegalovirus
• FOXP3
• human
• regulatory T cells
• in vitro