IL4 and B-cell chronic lymphocytic leukemia: Secretion of exosomes from B-cell lines is well documented but their release from normal or malignant primary B-cells is less well studied.[42–44] The generation of exosomes is not a constitutive activity of normal B cells, but is induced following activation signals such as IL-4 and anti-CD40.[45, 46] For our studies, we examined the miR cargo of primary CLL derived exosomes given the importance of miRs in CLL biology.[17, 18] Of significance, we show that CLL exosomes are highly enriched for small RNA species.