Effect of ADP on S aureus internalization by platelets.

(A) Washed control platelets incubated with a S aureus suspension. Platelets remain discoid and fully granulated, displaying no morphological signs of activation. Bacteria (arrowheads) remain in the extracellular space and are not internalized within platelets. Original magnification, × 14 040. (B) Washed platelets stimulated with 10 μM ADP and incubated with S aureus. Some bacteria (arrowheads) have been internalized by platelets. These platelets present signs of morphological activation: loss of discoid shape, extension of small pseudopods (p), dilated OCS, disappearance of cytoplasmic granules. Original magnification, × 14 040.