Severe invasive GAS rapidly induce necrosis to human PMN 
In an acute bacterial infection, PMN were quickly recruited at the site of infectious foci according to the gradient of chemoattractants.
Therefore, we examined whether GAS clinically isolated from severe invasive infections could affect the migration ability of PMN in response to chemokines.
As a model of local infection of the initial phase, we utilized a transwell system and added IL-8 and GAS in culture medium within the lower wells.
PMN were applied in the upper wells and subsequently incubated for 90 min.
As shown in Figure 2A and 2B, a substantial number of PMN, consisted largely of viable cells, was detected in the lower wells consisted of IL-8 and non-invasive GAS, as a control.
Contrarily, number of PMN was significantly low in the presence of severe invasive GAS (p=0.016) compared to that of control culture.
Flow cytometry analysis suggested that although PMN was detected in the lower well consisted of IL-8 and severe invasive GAS, but most of them were dead as defined by propidium iodine staining (p=0.016) (Figure 2A and 2C) demonstrating that severe invasive GAS affected survival of PMN and its migration activity in a transwell system.
