Comparison of rates of virus isolation from leukocyte populations separated from blood by conventional and Ficoll-Paque/Macrodex methods.

One hundred fifty-two blood specimens, largely from immunocompromised patients, were collected in heparinized Vacutainer tubes and divided into paired aliquots of equal volume. Buffy-coat preparations, containing mixed leukocyte and separate mononuclear and polymorphonuclear leukocyte populations were obtained by treatment of blood with conventional and Ficoll-Paque/Macrodex (F-P/M) methods. The development of cytopathic effect in monolayers of WI-38 fibroblasts inoculated with cell suspensions derived from the two methods was used to assess virus infectivity. Twice as many virus isolations were obtained using F-P/M. Of those viruses isolated by both conventional and F-P/M, the development of cytopathic effect was more extensive using the latter method. Moreover, a greater variety of viruses was isolated using F-P/M method, as compared to the conventional method. The F-P/M method is no more time consuming than conventional procedures, is readily adaptable for use in the diagnostic virology laboratory, requires only minimal additional cost, and is a particularly suitable and effective means of monitoring viremia.