Kinetics of CD15-mediated TNF-α release. Human peripheral blood mononuclear cells (2 × 10⁶) were purified as in Fig 1 and incubated with primary anti-CD15 IgM PM81 (10 μg/mL), anti-lactosamine IgM IB2 (10 μg/mL) or no MoAb. Following addition of a cross-linking secondary F(ab) ′₂ goat anti-mouse IgM, culture supernatants were harvested at various timed points from 2 to 6 hours. TNF-α levels in the supernatant were then determined by ELISA after centrifugation to remove cellular debris. One of three representative experiments with similar results is shown. Each point represents mean TNF-α released. Standard deviations (not shown) were 10% or less of the means.