Fig. 4.

CD11b/CD18 does not mediate phagocytosis of unopsonized Ft. (A) MDM in RPMI containing 10% HI-FBS were left untreated or preincubated with 25 μg/ml anti-CD18, anti-CD11b, anti-CD11a, or a mixture of anti-CD18 and anti-CD11b antibody prior to addition of Ft at a MOI of 20:1, and phagocytosis was quantified after 1 h at 37°C. In all cases, blocking antibodies were without effect (P>0.05). Data are the mean ± SD of triplicate samples from a representative experiment and are normalized to the no-antibody control (6±3 Ft/100 MDM). Similar data were obtained in two other independent experiments. (B) MDM were infected with LVS in RPMI + 10% HI-FBS for 5 min at 37°C. Confocal sections show that CD11b was not recruited to forming phagosomes containing unopsonized bacteria (arrowheads).