Induction of human granulocyte chemiluminescence by bacterial lipopolysaccharides

Bacterial lipopolysaccharides (LPS) have been reported to influence the oxidative response of human polymorphonuclear leukocytes (PMN). However, results sometimes conflict. In the present study, we demonstrated that activation of human PMN by LPS depends on the class (smooth [S] or rough [R]) to which the LPS belongs. Lucigenin-dependent chemiluminescence was used to assay oxygen radical production. Twenty different S- and R-form LPS and free lipid A were tested in concentrations of 0.01 to 100 micrograms/ml. S-form LPS activated PMN only at maximal concentrations and to a low extent. R-form LPS and free lipid A were potent inducers of granulocyte chemiluminescence even at a concentration of 0.1 microgram/ml. The results indicated that R-form LPS are very effective in inducing granulocyte chemiluminescence, whereas true S-form preparations are inactive. It is not known at present whether this higher activity is due to a more lipophilic character of R-form LPS or whether the presence of the O polysaccharide in S-form LPS exerts an inhibitory effect on their action on granulocytes.