Purging effect of reovirus on SLL cells. (A) Cytopathic effect of reovirus on human SLL cells 72 hours after infection. Purified cells were infected with reovirus (40 MOI), and cells were photographed 72 hours after infection (original magnification, × 200). Cytopathic effect was seen in reovirus-infected but not in uninfected cells. (B) Flow cytometric analysis of SLL following reovirus purging. Apheresis product cells were mixed with SLL cells (10%) and purged for 5 days with reovirus. Samples were analyzed using flow cytometry. Dim CD5⁺CD19⁺CD20⁺ B cells were gated using 2 regions (A and B) and assessed for clonality. The λ-positive SLL cells were clearly distinguished from the normal polyclonal B cells. (C) Representative histograms of viable SLL cells before and after purging with reovirus. The arrow indicates that SLL cells were not detected.