LPS was not involved in CD15-mediated TNF-α release. Human peripheral mononuclear cells were isolated and CD15 was cross-linked as in Fig 1. Incubation of either primary MoAb PM81 alone or secondary antibody alone did not increase TNF-α release. Also, boiling the primary MoAb (100°C for 15 minutes) abrogated the TNF-α-inducing effect. Incubating mononuclear cells with phosphoinositol specific phospholipase C (PIPLC, 15 μg/mL) for 60 minutes at 37°C, to remove the LPS receptor (ie, CD14) before cross-linking with CD15 MoAb had no effect. ⁺ = Significantly different from control (P < .05).