A, kinetics of LTC4 generation by mouse peritoneal macrophages stimulated with zymosan (10 particles/cell). B, peritoneal macrophages isolated from BALB/c mice were stimulated with unopsonized zymosan (10 particles/cell) for 15 and 60 min, fixed in 2% paraformaldehyde, permeabilized with 0.025% saponin, and incubated with specific antibodies for each of the enzymes of LTC4 biosynthesis followed by FITC-conjugated secondary antibodies. C, to demonstrate LTC4 formation at the phagosome, the cells were fixed with EDAC and immunostained with rat mAb anti-Cys-LTs followed by Cy3-conjugated donkey anti-rat IgG. Immunofluorescence images are paired with the corresponding Nomarski or bright field image.