Specific blood group antibodies inhibit Shigella flexneri interaction with human cells in the absence of spinoculation.

The classical models of investigating Shigella flexneri adherence and invasion of tissue culture cells involve either bacterial centrifugation (spinoculation) or the use of AfaE adhesin to overcome the low infection rate observed in vitro. However clinically, S. flexneri clearly adheres and invades the human colon in the absence of 'spinoculation'. Additionally, certain S. flexneri tissue cell based assays (e.g. plaque assays and infection of T84 epithelial cells on Transwells®), do not require spinoculation. In the absence of spinoculation, we recently showed that glycan-glycan interactions play an important role in S. flexneri interaction with host cells, and that in particular the S. flexneri 2a lipopolysaccharide O antigen glycan has a high affinity for the blood group A glycan. During the investigation of the effect of blood group A antibodies on S. flexneri interaction with cells, we discovered that Panc-1 cells exhibited a high rate of infection in the absence of spinoculation. Select blood group A antibodies inhibited invasion of Panc-1 cells, and adherence to T84 cells. The use of Panc-1 cells represents a simplified model to study S. flexneri pathogenesis and does not require either spinoculation or exogenous adhesins.