a, Wild-type Y. pestis KIM D27 or its ΔlcrV variant (KLD29) were added to U937 cells (MOI of 10) and adherence quantified as percent inoculum. b, Adherence of Y. pestis KIM D27 to U937, FPR1−/− and FPR1−/− (pFPR1) cells. c, Treatment of U937 cells with 10 μM fMLF or αLcrV or LcrVS228 (10–103 ng/ml) reduces Y. pestis KIM D27 adherence. One of three repeats is shown and error bars represent the s.e.m. (n = 3 biological replicates) (a-c). Significant differences were measured with the two tailed t-test (a), and one-way ANOVA with Bonferroni post-hoc analysis (b, c): ***, P<0.001; ns= not significant. d, Cleared detergent lysates of U937 or FPR1−/− (pFPR1STREP) cells were incubated without (left panel) or with 10 MOI Y. pestis KIM D27 (right panel) and subjected to affinity chromatography on StrepTactin-sepharose. Load (L) and eluate (E) samples were analyzed by immunoblotting with IgG specific for FPR1, actin, YopD, LcrV, and RpoA. One of three repeats is shown.