P-selectin–IgG chimera triggers genistein-sensitive, β2-integrin–dependent PMN aggregation and stimulates protein-tyrosine phosphorylation. (A) PMN were incubated in standard conditions in the presence of 50 μg/mL of nonimmune human IgG in the absence (control) or in the presence of 10 μg/mL of P-selectin–IgG chimera (P-sel). PMN were preincubated with the anti-CD18 antibody (IB4) or with genistein (GEN) as reported in Figs 2 and 3. The reaction was stopped, and PMN remaining single, nonaggregated were counted by optical microscopy in a Burker chamber. Values (means ± SEM, n = 3 or 4) are reported as percentage of the basal level. (B) PMN were challenged with P-selectin–IgG chimera as reported above. The reaction was stopped at different times. The figure shows the Western blot from a representative of three different experiments and the corresponding optical density of P∼110 (mean ± SEM, n = 2 or 3).
