Release of gram-negative outer-membrane proteins into human serum and septic rat blood and their interactions with immunoglobulin in antiserum to Escherichia coli J5

Prior studies indicate that 3 bacterial outer-membrane proteins (OMPs) are released into serum associated with lipopolysaccharide (LPS) and are bound by IgG in antiserum to Escherichia coa J5 (anti-J5 IgG). The present studie s analyzed the interaction of the OMPs with anti-J5 IgG and evaluated their release in an infected burn model of gram-negative sepsis, Affinity purifi cation studies were performed on filtrates of bacteria incubated in human s erum and plasma from rats with sepsis by use of O chain-specific anti-LPS I gG and anti-J5 IgG. All 3 OMPs were captured from septic rat blood by anti- LPS IgG, Release of OMPs into serum was highest for immature bacterial cult ures and was increased by antibiotics in vitro and in vivo. Anti-J5 IgG sel ectively captured an 18-kDa OMP released into serum and into plasma from se ptic rats. The results raise the possibility that anti-J5 IgG may, in part, protect via anti-OMP antibodies.