Infection of Primary Human Myeloid Cells.

Circulating phagocytic cells often serve as cellular targets for a large number of pathogens such as parasites. Studying primary human cells in an infectious context requires lengthy procedures for cell isolation that may affect the analysis performed. Using whole blood and a no-lyse and no-wash flow cytometric assay ( assay), we monitored the infection of primary human cells. We demonstrated, using fluorescent parasites, that among monocyte cell populations, preferentially infects classical (CD14CD16) and intermediate (CD14CD16) primary human monocytes in whole blood. Because classical monocytes are the preponderant population, they represent the larger reservoir. Moreover, we also found that, concomitantly to monocyte infection, a subset of PMNs is infected early in whole blood. Of interest, in whole blood, PMNs are less infected compared to classical monocytes. Overall, by using this assay, we provided a novel avenue in our understanding of host-leishmania interactions.