Binding of vitronectin and clusterin by coagulase-negative staphylococci interfering with complement function

Coagulase-negative staphylococci (CoNS) are commonly associated with infect ions of prosthetic devices mediated by adsorbed host factors on biomaterial surfaces. Complement activation is known to occur and induce unspecific in flammation around the biomaterials. Human vitronectin (Vn) and clusterin (C lu), two potent inhibitors of complement, can be bound by CoNS. With a hypo thesis whether binding of Vn or Clu influences complement activation, two m easurements were determined. For Vn, complement activation was measured wit h a mouse anti-activated human C9 antibody. In the presence of Vn-binding s train, Staphylococcus hemolyticus SM13I, complement activation on a surface pre-coated with Vn occurred as it did in the absence of Vn pre-coating. Fo r S. epidermidis 3380, which does not express binding of Vn, complement act ivation on a Vn-presented surface was significantly decreased. For Clu, ery throcytes lysis was measured to reflect the end product of complement activ ation (membrane attack complex). The complement-induced hemolysis increased when human serum was pre-incubated with Clu-binding strains, S. epidermidi s J9P. The enhancement of hemolysis by J9P decreased when serum was supplem ented by exogenous Clu. The data imply that interaction between CoNS and Vn or Clu interferes with one of their physiological functions, complement in hibition. (C) 2001 Kluwer Academic Publishers.