Exposure To Dextran During Isolation Enhances The Chem0- Tactic Response Of Human Peripheral Polymorphonuclear Leukocytes To Synthetic N-F-Met-Leu-Phe But Not To Zymosan Activated Serum (ZAS)

The effect of the method of isolation of human peripheral polymorphonuclear leukocytes (PMN) on their chemotactic response to ZAS and N-f-met-leu-phe was studied. Chemotoxis was measured in Boyden chambers by counting the cells at consecutive 10 μM depths of the filters and calculating the chemotactic index (CI). PMN isolated by two-step ficoll-hypaque gradients and resuspended in medium 199 with 0.035% human albuman had a control CI of 9.75. With ZAS (1:2) as the chemoattractant in the lower chamber (1 hr at 37°C, CO₂ incubator) the CI was 31.44 (222% increase). Exposure of gradient isoalted PMS to a 1-1000 dilution of DMSO increased the baseline CI to 24.72 when the medium remained the same. N-f-met-leu-Phe as the chemoattractant in the lower chamber illicited a very modest (19% increase) over a range of 10_-10 to 10_-5 M. In contrast, PMN isolated by a combination if ficoll- hypaque cushion and dextran sedimentation responded to N-f-met-leu-phe with an increase from baseline CI of 18.75 to stimulated CI of 33.18 at 10_-8 M (77% increase). After exposure to dextran PMN isolated by the two-step gradient also responded to N-f-met-leu-phe. Thus, a low concentration of dextran or other glucose polymer may be required for the response of PMS to synthetic chemotactic peptides. This is consistent with the wide spread use of PMN isolated by dextran sedimentation or PMN from pero-tineal exudate elicited by the injection of glycogen solution. Glucose polymers might replace bacterial surface carbohydrates and function to absorb the peptides thereby making an active polyvalent ligand.