In this review the interaction between invasive human pathogens expres
sing plasmin(ogen) receptors and/or producing plasminogen activators w
ith the human plasmin(ogen) system is described. Evidence is presented
for multiple mechanisms by which human pathogens can acquire a surfac
e bound form of plasmin that cannot be regulated by host serpins. The
potential importance of these pathways in providing the organisms with
the ability to cross tissue barriers is discussed.