CD4 and rheumatoid arthritis: Consistent with the poor proliferative but good cytokine response of RA T cells in response to citrullinated peptides in the current studies, CD4+CD45RBdimCD27- memory T cells from healthy donors were previously shown to proliferate poorly but to produce large amounts of IL-4 and IL-10 in response to mitogen, and to provide effective B-cell help for immunoglobulin production [40].