B220 is an antiviral agent which can inhibit the growth of HSV-1, HSV-2 and human cytomegalovirus (CMV). B220 inhibits neutrophil release of reactive oxygen species, as well as intracellular generation of reactive oxygen species. The inhibition is not achieved through direct oxygen radical scavenger activity of B220, and B220 has no immediate effects on the activity of the assembled oxidase. The neutrophil capability to phagocytose fluorescein-labeled opsonized yeast cells is reduced by B220. Cells preincubated with B220 (10 μg/mL) and then stimulated with the formylated peptide fMLP mobilize fewer C3 receptors on their surface than the control cells.