Fig. 1

Bovine PMN are responsive to IL-8, but unresponsive to fMLP in the chemotaxis assay. A Schematic representation of the chemotaxis assay. Bovine PMN are loaded into the upper chamber of a Transwell inset and are allowed to migrate through the porous bottom membrane toward the lower chamber containing chemotactic stimuli (left) or whole Lm, either free in medium (upper right) or trapped under a layer of agarose (lower right). Free bacteria move into the upper chamber, while the agarose layer limits Lm access to the upper chamber (see also Fig. 2C). B PMN chemotaxis toward medium alone (control, random migration), bovine IL-8 (positive control), and fMLP at a concentration of 0.1 and 1 µM. Data are represented as means on a superimposed scatter dot plot of 3 independent experiments, each performed in triplicates. Data are color-coded according to the donor cows, from which PMN were extracted. Statistical analyses: Mann–Whitney U tests (**P < 0.01; ns non-significant)