INCREASED SURFACE EXPRESSION OF CD11B C AND CD18 APPEARS TO BE DISSOCIATED FROM ANTI-CD11B/C MONOCLONAL-ANTIBODY STIMULATED O2-, ANION GENERATION IN IN-VIVO ESCHERICHIA-COLI LIPOPOLYSACCHARIDE AND TUMOR NECROSIS FACTOR-ALPHA-TREATED RAT NEUTROPHILS/

The purpose of this investigation was to determine the effect of anti- rat CD11 b/c monoclonal antibody (MAb) on in vitro superoxide anion (O -2(-)) generation in in vivo Escherichia coli lipopolysaccharide (LPS) and tumor neorosis-alpha (TNF)-treated rat polymorphonuclear leukocyt es (PMN). After a continuous infusion of a nonlethal dose of E. coli L PS (.5 mg/kg) or TNF (6.0 x 10(5) units) into rats, PMN were recovered by centrifugal elutriation and discontinuous density gradient centrif ugation from the liver (LPS-treated) and whole blood (LPS- and TNF-tre ated) and compared for CD11b/c, CD11a, and CD18 upregulation and their capacity for basal and agonist-stimulated O-2(-) production. Immunofl uorescence flow cytometry studies of rat whole blood PMN demonstrated that, upon LPS infusion, there was a time-dependent upregulation of CD 11b/c and CD18, but not of CD11a. Similarly, TNF infusion upregulated CD11b/c although to a lesser degree. Stimulation of LPS- and TNF-treat ed PMN with phorbol 12-myristate 13-acetate (PMA), opsonized zymosan ( OPZ), and anti-rat CD11b/c MAb triggered O-2(-) generation. Although t otal O-2(-) generated by OPZ and anti-rat CD11b/c MAb was less than th at generated by PMA stimulation, the in vivo LPS- and TNF-induced beta (2) integrin upregulation did not result in a statistically significan t enhancement of O-2(-) generation with respect to normal saline-treat ed PMN. Our results do not appear to support the hypothesis that enhan ced expression of CD11b/c or CD18 might be associated with enhanced in vitro anti-CD11b/c MAb-triggered O-2(-) generation in LPS- and TNF-tr eated PMN in vivo.