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Effect of phagocytosis by human polymorphonuclear leukocytes and rabbit alveolar macrophages on 2-deoxyglucose
Abstract:
2-Deoxyglucose transport was characterized in human polymorphonuclear leukocytes (PMN) and rabbit alveolar macrophages (AM). The Km was 1 mM for human PMN and 1.6 mM for rabbit AM, and the Vmax was 0.66 x 10(-3) micromoles/45 sec/10(6) PMN and 5.09 x 10(-4) micromoles/45 sec/10(6) AM. The rate of 2-deoxyglucose transport was the same before and after phagocytosis in PMN from normal individuals and three patients with chronic granulomatous disease, as well as rabbit AM. Studies of the kinetics of 2-deoxyglucose transport and intracellular fate of 2-deoxyglucose in human PMN indicate that the nature of the membrane transport system is not altered by phagocytosis. The results support the concept that the plasma membrane is mosaic in character with geographically separate transport and phagocytic sites.
Insights
This study shows that glucose transport in human white blood cells (PMN) and rabbit macrophages (AM) remains unchanged after phagocytosis. This suggests separate sites for transport and cell engulfment on the cell membrane.
Area of Science:
- Cell biology
- Immunology
- Biochemistry
Background:
- Glucose transport is crucial for cellular energy.
- Phagocytosis is a key immune process involving cell engulfment.
- Understanding these processes in immune cells is vital.
Purpose of the Study:
- To characterize 2-deoxyglucose transport kinetics in human polymorphonuclear leukocytes (PMN) and rabbit alveolar macrophages (AM).
- To investigate the effect of phagocytosis on glucose transport in these cells.
- To explore the functional organization of the leukocyte plasma membrane.
Main Methods:
- Characterization of 2-deoxyglucose (a glucose analog) transport using kinetic analysis (Km and Vmax).
- Comparison of transport rates before and after phagocytosis in human PMN and rabbit AM.
- Evaluation of cells from normal individuals and patients with chronic granulomatous disease.
Main Results:
- Kinetic parameters (Km and Vmax) for 2-deoxyglucose transport were determined for both cell types.
- Phagocytosis did not alter the rate of 2-deoxyglucose transport in human PMN or rabbit AM.
- Transport rates were consistent in PMN from normal individuals and patients with chronic granulomatous disease.
Conclusions:
- The mechanism of 2-deoxyglucose transport in human PMN is not affected by phagocytosis.
- Results support a mosaic model of the plasma membrane with distinct transport and phagocytic domains.
- Immune cell membrane function exhibits specialized, spatially separated sites.