Manno(rhamno)biose-containing capsular polysaccharides of klebsiella pneumoniae enhance opsono-stimulation of human polymorphonuclear leukocytes

Abstract

We tested the relationship between the capsular and the O-antigen structures and the ability of bacteria to trigger respiratory burst in human polymorphonuclear leukocytes (PMNL).Capsulated and non-capsulated variants as well as capsule-switched derivatives of Klebsiella serotypes bearing or lacking manno(rhamno)biose repeats in their capsular polysaccharides and expressing either mannose-rich or mannose-poor O antigens were tested for their ability to induce respiratory burst and survive in human PMNL. Luminol-enhanced chemiluminescence (CL) was measured to quantify respiratory burst. Intracellular survival was quantified by determining the viable counts of intracellular bacteria. K serotypes and the capsule-switched derivative lacking manno(rhamno)biose induced significantly lower CL than those expressing manno(rhamno)biose. Manno(rhamno)biose-lacking serotypes survived in the cells significantly better than serotypes expressing these repeats. C1q depletion did not affect CL induced by the manno(rhamno)biose-containing serotype, whereas factor B depletion revealed a significantly reduced CL. Likewise, EGTA in the presence of Mg 2+ significantly decreased CL, but the values were higher than those induced by the bacterium opsonized with factor B-depleted serum. In the presence of EGTA, Mg 2+-treated factor B-depleted serum revealed a significant reduction in the CL response compared with the responses induced by opsonization with factor B-depleted serum alone. These results indicate, in addition to the alternative pathway, a manno(rhamno)biose pattern recognition of Klebsiella by PMNL probably by the complement lectin pathway. Copyright © 2008 S. Karger AG, Basel.