High Resolution Autoradiographic Studies of RNA, Protein and DNA Synthesis during Human Eosinophil Granulocytopoiesis: Evidence for the Presence of RNA on or within Eosinophil Granules

Human bone marrow cells which had been incubated with 3H]uridine or 3H]leucine for I h were studied using the technique of electron microscope-autoradiography. The autoradiographs revealed the presence of newly-synthesized RNA and protein molecules within or on a proportion of (I) the primary and secondary granules in all classes of eosinophil precursors and (2) the secondary granules in eosinophil granulocytes. It is suggested that the granule-associated RNA molecules may be concerned with the synthesis of at least some of the new protein molecules which were incorporated into the limiting membrane or substance of eosinophil granules long after the immature primary granule stage. Studies of eosinophil precursors which had been incubated with 3H]thymidine for I h showed that the eosinophil granules do not label with this DNA precursor.