Carrageenan stimulates reduction of nitroblue tetrazolium by human neutrophils without membrane depolarization, myeloperoxidase secretion, or increased oxygen consumption.
The mode of action of carrageenan (9000071), a sulfated polyanionic polysaccharide, was investigated in human neutrophils (PMN), in a serum free medium. Carrageenan is an inflammatory agent that is commonly used to test antiinflammatory drugs. PMNs were isolated from citrated whole human blood by countercurrent elutriation and were used for in-vitro experiments, in which they were stimulated by carrageenan and tested for several parameters. Included in the criteria tested were, their effect on nitroblue-tetrazolium (NBT) reduction, oxygen consumption, hydrogen-peroxide reduction, luminol dependent chemiluminescence, release of myeloperoxidase and lactate- dehydrogenase, and membrane depolarization. Carrageenan stimulated the reduction of NBT by PMNs, but did not stimulate membrane depolarization, oxygen consumption, hydrogen-peroxide production, or myeloperoxidase secretion. The authors conclude that carrageenan stimulates a heat labile, NBT reducing system, a mechanism different from that of other PMN activators.