Oxidation of glucosamine by human polymorphonuclear leukocytes

When exposed to a phagocytic stimulus (opsonized zymosan), human polymorphonuclear leukocytes (PMNs) produced 14CO2 from [1-14C]glucosamine at a rate 10-25% of that produced from glucose under the same conditions. The production of CO2 from glucosamine by intact PMNs was inhibited by glucose and dependent upon activation of the hexosemonophosphate shunt (HMPS). However, the metabolic pathways for the oxidation of glucose and glucosamine by PMNs are not identical. This is suggested by the fact that glucose-6-phosphate dehydrogenase, the initiating enzyme for the HMPS, did not utilize glucosamine-6-phosphate as a substrate. In addition, glucosamine was not oxidized by sonically disrupted PMNs whereas oxidation of glucose by the same preparation was increased sevenfold over intact cells. Taken together, the data suggest that PMNs oxidize glucosamine by converting it to a compound compatible with the enzymes of the HMPS. This conversion requires intact PMNs and/or an as yet unidentified cofactor.