Fig. 7.
Engagement of PSGL-1 by the monoclonal antibody PL2 triggers genistein-sensitive, β2-integrin–dependent PMN aggregation and stimulates protein-tyrosine phosphorylation. (A) PMN were preincubated at 4°C with PL2 (anti-PSGL-1), rapidly washed to remove unbound antibody, and incubated in the absence [PL2-F(ab)2] or in the presence [PL2+F(ab)2] of 10 μg/mL of rabbit anti-mouse IgG F(ab)2 fragments in standard conditions. The anti-CD18 antibody (IB4) was preincubated with PMN together with PL2 for 15 minutes at 4°C before cross-linking. PMN were treated with genistein (10 μg/mL; GEN) for 1 minute after preincubation with PL2 and before cross-linking. In control experiments, PMN were preincubated at 4°C with HC1.1 (anti-CD11c), washed to remove unbound antibody, and incubated in the presence of 10 μg/mL of anti-mouse F(ab)2 fragments in standard conditions [HC1.1+F(ab)2]. PMN aggregation was evaluated as in Fig6. Values are means ± SEM (n = 3). (B) PMN were treated and incubated exactly as for aggregation experiments. The figure shows the Western blot of a representative of three different experiments and the corresponding optical density of P∼110 (means ± SEM, n = 2 to 3).