IgG binding to immobilized IL-8 and IL-8–dependent platelet procoagulant activity induced by IgG.
(A) Purified total IgG from patient P1 (black line) was injected over the IL-8–coated biosensor for 1200 seconds, followed by running buffer (spontaneous dissociation) for an additional 1200 seconds. Control sensorgram obtained with purified total IgG from a healthy donor is displayed as the gray line. (B) Washed human platelets from a healthy donor were incubated with serum (black bars; 5 mg IgG/mL), purified total IgG (white bars; 2.4 mg/mL), or affinity-purified anti–IL-8 IgG (gray bars; 7.7 μg/mL) from patient 1. Varying concentrations of IL-8 were added to the mixture, without or with unfractionated heparin (0.1 U/mL). With P6 control serum containing only IgG against heparin-PF4 (hatched bars, 2.35 mg IgG/mL), significant activation was recorded only in the presence of heparin alone. (C) Platelets were pretreated with buffer alone, acetylsalicylic acid (ASA), PGE1, or FcγRIIa receptor–blocking antibody IV.3 before incubation with P1 serum (black bars) or purified total IgG (white bars).
