Figure 1.

MV infection induces syncytia in cultured DC and skin LC. DC derived from day 9 cultures of cord blood CD34⁺ progenitors were either mock-infected (a and d  ) or infected with either MV-Hallé (b and e) or MV–LYS-1 (c and f  ) at an MOI of 0.05. DC syncytia were observed on day 2 of infection by phase-contrast microscopy analysis (final magnification, ×400) (a–c) and by May-Grunwald Giemsa staining (final magnification ×400 (d  ); ×1,000 (e and f   )). LC-enriched epidermal cell suspensions either uninfected (g) or infected with the Edmonston strain at an MOI of 0.05 (h) were cultured for 3 d in the presence of 100 ng/ml of rGM-CSF. On day 3 of infection, the cells were processed for staining with a polyclonal rabbit antiserum directed against S100 and counterstained with hematoxylin. No staining was detected with control normal rabbit serum (not shown). (g) Specific staining of LC for S100 in uninfected LC-enriched suspension; (h) S100 expression by LC syncytia in MV-infected LC-enriched suspension. ×400. The results are representative of five experiments.