Exogenous laminin 8 protects neutrophils from apoptosis. The percentage of annexin V–binding cells (A) and the degree of caspase-3–like enzyme activity (B) were used as markers of apoptosis. Neutrophils were incubated for 12 hours at 37° C on plates coated with human serum albumin (HSA), mouse laminin 1 (mLN-1), recombinant human laminin 8 (rhLN-8), and recombinant human laminin 10 (rhLN-10). (A) Cells were incubated with both fluorescein isothiocyanate–annexin V and propidium iodide and analyzed by flow cytometry. Cells stained with only annexin V were considered apoptotic. (B) Caspase-3–like activity was determined by the in vitro cleavage of the fluorescent peptide substrate, DEVD-AMC. Mean and SD of 7 experiments for each assay are shown. P values (*P < .05; ***P < .001) compare laminin isoforms with HSA at 12 hours.