CD4 and colitis: Encouraged by recent reports of exosome functionality and treatment effects [4,13,14,15,16], specifically by findings showing G-MDSC-exos suppressed immune responses and attenuated disease in animal models of colitis [17,18,19], and that G-MDSC-exos augmented delivery of miRNA to CD4+ T cells in a mouse model of rheumatoid arthritis [17], we reasoned that the therapeutic efficacy of G-MDSCs in murine AA/BMF might be partially mediated by G-MDSC-exos.