IL-1β–stimulated PMN transmigration is composed of PECAM-1–dependent and –independent components.

Cell monolayers were treated for 24 hours with 10 U/mL IL-1β (luminal). Transmigration rates are expressed as the proportion of transmigrating PMNs compared with “unblocked” controls (set at 1.0). Data represent the mean ± SEM from a minimum of 3 transwells for each condition from at least 3 separate experiments unless otherwise indicated. (*Significantly different from “unblocked” controls,P < .05.) (A) Transmigration following exposure of neutrophils and REN or RHP monolayers to anti–PECAM-1 (Houston, ▨) or anti-β2 microglobulin (░) antibodies. (B) Transmigration following exposure of PMN and REN or RHP monolayers to anti-β2 microglobulin (reference set at 1.0), anti–MHC-1, anti-βGal antibodies, BSA, or anti–PECAM-1 (Houston) antibodies (all 100 μg/mL). (C) RHP cells. Luminal BSA (“unblocked” reference control) or anti–PECAM-1 antibodies Houston, mAb62, Hec7, or 4G6 (100 μg/mL) were added as indicated. Data represent the mean ± SEM from a minimum of 3 transwells for each condition from at least 2 separate experiments. (D) Confluent REN monolayers transduced with Ad.PECAM-1 or Ad.LacZ (PECAM null) and subsequently treated for 24 hours with 10 U/mL IL-1β (luminal). PMNs and tranduced REN monolayers were exposed to anti–PECAM-1 (Houston, ▨) or anti–MHC-1 (░) antibodies as indicated. Values are normalized to LacZ transfected (PECAM-1 null), “unblocked” (anti–MHC-1 antibody-treated), negative control. (*Significantly different from Ad.LacZ negative controls,P < .05; **significantly different from “unblocked” Ad.PECAM-1, P < .05.)