Invasin of Yersinia pseudotuberculosis activates human peripheral B cells

The Yersinia pseudotuberculosis cell surface-located protein invasin was found to promote binding between the pathogen and resting peripheral B cells via beta(1) integrin receptors (CD29). B cells responded by expressing several activation markers and by growing. In contrast, T cells did not react, although these cells express CD29. An isogenic invA mutant failed to activate B cells. The mutation could be complemented by providing the invA(+) gene in trans. Purified invasin alone did not activate B cells, although it was able to block the binding of bacteria to the cells.