CHARACTERIZATION OF 2 MONOCLONAL-ANTIBODIES DIRECTED AGAINST BACTERICIDAL PERMEABILITY-INCREASING PROTEIN

In this study the production and characterization of two monoclonal an tibodies (MAbs), 4E3 and 5D7, against the bactericidal/permeability-in creasing protein (BPI) were described. Using ELISAs, both 4E3 and 5D7 were shown to detect recombinant (r) BPI. Furthermore, natural BPI pre sent in polymorphonuclear leukocytes (PMNL) was detected by both 4E3 a nd 5D7. The use of both MAbs in flow cytometry revealed that PMNL expr essed low levels of cell-surface BPI. Lipopolysaccharide (LPS) was sho wn to block the interaction between anti-BPI MAb and rBPI. In addition , the MAbs blocked biologic activity of rBPI. The inhibition by BPI of LPS activation of the limulus amebocyte lysate assay and of LPS-induc ed tumor necrosis factor-alpha release by monocytes was prevented by 4 E3 and 5D7, Both MAbs are specifically directed against BPI and can in hibit BPI bioactivity.