The green tea extract epigallocatechin gallate is able to reduce neutrophil transmigration through monolayers of endothelial cells.

: Green tea is widely used in Asia and has also become popular in Western countries. The influence of green tea extracts on leukocytes is not well understood. Leukocytes play a crucial role in the process of inflammation. They migrate from the intravascular space into the tissue to attack micro-organisms. The aim of the current study was to investigate the influence of epigallocatechin gallate on leukocyte transmigration through endothelial cell monolayers and thereby evaluate its potential role in the inflammatory process. Human umbilical vein endothelial cells were cultured on microporous membranes to achieve a monolayer. Freshly isolated neutrophils from healthy subjects were measured with a migration assay. The amount of untreated neutrophils migrating through untreated endothelial cell monolayers was used as control and set as 100%. Neutrophils and/or endothelial cell monolayers were pre-treated with epigallocatechin gallate using relevant, as well as higher and lower concentrations. The relevant plasma concentration of epigallocatechin gallate was able to significantly inhibit neutrophil migration through endothelial cell monolayers (69 +/- 6.4% SD; p < 0.05 compared to control), when both cell types (leukocytes and endothelial cell monolayer) were treated. This is similar to the situation after resorption in-vivo. Treating either neutrophils or endothelial cell monolayers alone led to significant reductions in migratory response (only neutrophils treated: 86 +/- 8.1% SD, p < 0.05; only endothelial cell monolayers: 77 +/- 6.1%, p < 0.05). In conclusion, epigallocatechin gallate was identified as a potent inhibitor of leukocyte migration through endothelial cell monolayers. The treatment of both cell types showed an additive effect. Endothelial cells seem to be more affected than neutrophils. Further clinical investigations are necessary to understand the potential clinical consequences.