LIPOPOLYSACCHARIDE AND SERUM CAUSE THE TRANSLOCATION OF G-PROTEIN TO THE MEMBRANE AND PRIME NEUTROPHILS VIA CD14

Lipopolysaccharide (LPS) in combination with human serum, in the absence of a second stimulus, causes an increase in the amount of the α -subunit (Giα2) of the guanine nucleotide binding protein Gi2 associated with the membrane. The LPS-serum complex also primes human neutrophils for O2- production in response to stimulation by the chemotactic factor fMet-Leu-Phe. Added serum factor is essential for priming at low concentrations of LPS. In the presence of serum, significant potentiation can be observed at LPS concentration as low as 0.1 ng/ml. The priming is dose and time dependent. Furthermore, the observed actions of the LPS-serum complex are not reversible since they cannot be overcome by washing. Monoclonal antibody against CD14 inhibits both the direct and priming actions of the LPS-serum complex. On the other hand, neither the antibody against CD11b nor the antibody against TNF-α inhibits the action of this complex. © 1992 Academic Press, Inc.