Abstract
Both wild‐type and attenuated strains of poliovirus type 3 were found to replicate in the U‐937 cells, an established cell line derived from human histiocytic lymphoma. However, preincubation of the cells with phorbol ester (PMA) that brought about the typical adherent macrophagelike appearance of the cultures, converted the cells to practically nonpermissive for poliovirus, while their ability to replicate vesicular stomatitis virus was not impaired. RC2A, another human cell line derived from monocytic leukemia, showed no detectable progeny virus production within 48 hr. Poliovirus replication in U‐937 cells may be a suitable model for detailed studies of poliovirus‐leukocyte interactions.