Figure 10.

αvβ5 integrin, but not αvβ3 integrin, requires actin microfilaments for apoptotic cell or OS binding. J774 macrophages were preincubated with or without 10 μM Cyt D for 5 min, then PMA or solvent was added for an additional 25 min. Cells were equilibrated to 18°C for 20 min and challenged with FITC-OS or apoptotic cells for 45 min. At this time point, 18°C binding was similar in amount to binding at 37°C (see Fig. 7). Binding by cells treated with DMSO or PMA alone reproduced the integrin inhibition pattern established for 30-min challenge at 37°C (see Fig. 6 b). Both integrins bound particles independently, as dual inhibition had an additive effect on particle binding by PMA-treated macrophages (cross-hatched bars). Cyt D reduced the particle binding index of PMA-activated samples to that of vehicle controls and abolished its sensitivity to αvβ5 inhibition. Binding indices are means ± SEM (n = 3) of results obtained with OS. Similar results were obtained challenging macrophages with apoptotic cells.