FIGURE 7.

Annexin V inhibits apoptotic cell recognition by C1q. Apoptotic HeLa cells were harvested 2 h after UV-B irradiation and incubated at 2.5 × 10⁵ cells/ml in the presence of increasing concentrations of annexin V for 20 min at room temperature in 140 mM NaCl, 5 mM KCl, 1 mM MgCl₂, 2.5 mM CaCl₂, and 25 mM HEPES (pH 7.4) containing 0.005% surfactant P20. Apoptotic and control cell samples were then passed over a C1q-coated sensor chip as described in Materials and Methods and cell capture was measured after association for 2 min as described in the legend to Fig. 1. Results are expressed relative to the capture of either viable cells or apoptotic cells by C1q in the absence of annexin V. The data shown represent the mean value ± SD of three independent experiments.