FIGURE 3.

LTB₄ potentiates Rac activation during FcγR-dependent phagocytosis. A, effect of BLT1 deficiency on Syk phosphorylation in BMMφ stimulated with IgG beads and LTB₄. BMMφ from WT and BLT1-deficient mice were incubated with IgG beads and 100 nm LTB₄ for the indicated periods of time. Cell extracts were separated by SDS-PAGE and immunoblotted with the indicated antibodies. B and C, effect of BLT1 deficiency on Rac activation. BMMφ from WT and BLT1-deficient mice were stimulated with IgG beads in the presence or absence of LTB₄ (B and C) and BLT1 antagonist CP105696 (C). Activated Rac (GTP-Rac) was pulled down with GST-PAK followed by immunoblotting. TCL, total cell lysates. GTP-Rac/Rac ratio was normalized to 1 for the WT (unstimulated) (C and D). Data represents the means ± S.D. (n = 3). ##, p < 0.05 versus #. D, effect of PTX on BLT1-dependent Rac activation in WT BMMφ. Cells were stimulated with LTB₄ in the presence or absence of PTX. Rac pulldown assay was performed as described above. Data represent the means± S.D. (n = 3). *, p < 0.05; **, p < 0.01.