FIG. 2.

Involvement of β₁ integrins in Yersinia-induced [Ca²⁺]_i elevations in neutrophils. Time courses of [Ca²⁺]_i in single neutrophils after receptor blockage and during infection with Y. pseudotuberculosis are shown. Adherent neutrophils were pretreated with blocking antibodies (10 μg/ml) directed against β₁ integrins (A) or HLA (B) for 10 min. The Y. pseudotuberculosis plasmid-cured strain was then added at a calculated bacterium/cell ratio of 50:1 (arrow). The “✗” symbol indicates contact between a bacterium and the neutrophil. Attachment of bacteria was visually observed on a video screen, and this was correlated with the [Ca²⁺]_i transients. Representative time courses are presented (of 4 to 10 separate experiments). The mean numbers of [Ca²⁺]_i transients are shown in Table 2.