Fig. 1. Complexity of phagocytic Ca²⁺ signals. A spectrum of ß2 integrin-mediated Ca²⁺ signals was observed. The left-hand column (a) shows examples of these Ca²⁺ signals as (i) single peak, (ii) a single broad peak, (iii) a shouldered peak and (iv) a twin peak. The right-hand column (b) shows Ca²⁺ responses in experiments in which individual neutrophils were challenged with two C3bi-opsonised particles. The character of the second response is similar to the first response by the same cell, whether (i) single peak, (ii) a single broad peak, (iii) a shouldered peak or (iv) a twin peak. In both sets of data, the upward arrow indicates the time of contact between the particle and the cell, and the downward arrow indicates closure of the phagosome.