CD46-activated IL-10–secreting CD4⁺ T cells express high amounts of CD40L and GM-CSF. Purified peripheral-blood T cells (sorted CD4⁺CD45RA⁺ cell population) were activated with the indicated immobilized mAbs for 18 hours, and Monensin was added to the last 8 hours of culture. Cells were permeabilized and fixed, and intracellular cytokine staining was then performed for (A) IL-10 and CD40L or (B) IL-10 and GM-CSF. Shown is 1 representative FACS analysis of 3 independently performed experiments (with each activation condition in triplicate). The observed level of significance for the differences in the amount of IL-10/CD40L or IL-10/GM-CSF production between CD3/CD28- and CD3/CD46-activated cells was P < .001 by the paired Student t test in all cases.