IL-2–KO macrophages have augmented phagocytosis activity. Splenic macrophages were seeded into tissue-culture plates overnight with and without LPS simulation. (A) Representative experiment showing E coli particle uptake by nonstimulated CD11b⁺ macrophages. The number in parentheses represents the mean fluorescent intensity (MFI). (B) Ratio of the MFI of E coli particle uptake by CD11b⁺ cells relative to nonstimulated WT cells is shown. Bar graph represents the mean plus or minus SD of 5 independent experiments. E coli particle uptake by unstimulated IL-2–KO CD11b⁺ cells is statistically different from all other genotypes (P < .05).