Neutrophils can present antigens to antigen-specific memory CD4⁺T cells but MDCs and monocytes have the highest capacity. Sorted APCs from CMV- or influenza-seropositive donors were pulsed respectively with CMV pp65 or influenza HA and cocultured with autologous CFSE-labeled CD4⁺ T cells. Their capacity to present antigen to CD4⁺ T cells was evaluated by measuring proliferating T cells (CFSE dilution). (A,B,D) Proliferating (CFSE low) CD4⁺ T cells in presence of the indicated APCs from 2 CMV-seropositive donors (A-B) or 1 representative HA-seropositive donor (D) are shown. Bars show percentages of (C) pp65-specific and (E) HA-specific proliferating CD4⁺ T cells (mean ± SEM, n = 6 and n ≥ 2 healthy human donors, respectively). **P < .01, *** P < .001, **** P < .0001.