Comparative effects of F1 and P1 fractions obtained from a Klebsiella pneumoniae glycoproteic extract (RU 41740) on polymorphonuclear leukocytes.

RU 41740 is a glycoprotein extract from Klebsiella pneumoniae described as a macromolecular aggregation of a lipopolysaccharide (LPS)-associated protein (F1 fraction) and a glycoproteic complex (P1 fraction). The human polymorphonuclear (PMN) response was studied after incubation of the cells in the presence of RU 41740, F1 and P1 fractions, or F1-P1 complex. Oxidative metabolism was assessed by chemiluminescence, O2 consumption, O2- generation, and degranulation by beta-glucuronidase release. Results were compared to data obtained with a homologous LPS. RU 41740, F1 fraction, and F1-P1 complex increased the respiratory burst of PMNs stimulated by opsonized zymosan (OZ). N-formylmethionylleucylphenylalanine (fMLP), phorbol myristate acetate, or the calcium ionophore A23187. The beta-glucuronidase release was stimulated by the same compounds when OZ or fMLP were used as stimuli. These effects were dose-dependent. In contrast, P1 fraction was inactive. Addition of polymyxin B resulted in a profound inhibition of both the F1 fraction and LPS activities but only in a partial inhibition of RU 41740 effects. These results strengthen the hypothesis that different biochemical pathways are involved in the enhancement of stimulated neutrophil functions by RU 41740.