FIGURE 2.
C1q binds dose-dependently to apoptotic Jurkats but not to live cells. A, Characterization of apoptotic cells. Apoptosis of Jurkat cells was induced in complete media (early apoptotic) or Xvivo serum-free media (late apoptotic). Cells were stained with Annexin V and PI and analyzed by flow cytometry. Data are from one experiment, representative of at least 10. B, Live, early apoptotic, or late apoptotic Jurkat cells were incubated with 0 μg/ml (filled histogram) or 75 μg/ml (open histogram) C1q. C, Cultures of live (◆), early apoptotic (■), or late apoptotic (□) Jurkat cells were incubated with 0–300 μg/ml human C1q for 30 min at 37°C before being washed. C1q binding was measured by the MFI of fluorescently labeled secondary Ab detection of anti-human C1q using flow cytometry. D, A typical dose-response histogram of C1q binding to late apoptotic Jurkats when incubated with purified C1q or 10% NHS. Data (B–D) are from a single experiment, representative of three.