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[Progress of leukocyte research]
13rd Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo.
Abstract:
Over 170 years ago Metchnikoff described the bacteriocidal activity of leukocytes. It has been clarified that leukocytes play an important role in first defense mechanism against infection due to microorganism. Leukocytes immigrate to the lesion, which various microorganisms invade across mucosal barrier, and phagocyte and kill ingested microorganisms. The inability of the chronic granulomatous disease (CGD) granulocytes to generate superoxide has prompted the analysis of NADPH oxidase responsible for superoxide generation. The study on CGD has provided profound informations into NADPH oxidase system of leukocytes. Recruitment leukocytes to inflammatory lesion is essential for the inflammatory process, and it is regulated by various chemotactic factors and the adhesion molecules interaction between leukocytes and endothelium of vessels. Identification of interleukin-8 (IL-8) to be one of chemotactic cytokines and its gene cloning offered the progressive understanding for the immigration mechanism of leukocytes from vessels to inflammatory lesion. On the other hand, LFA-1 deficiency revealed that emigration, adhesion and phagocytosis of leukocytes are associated closely with the adhesion molecules on their surfaces. More recently, the cytokine networks of myelopoiesis or inflammatory process have been clarified. Among various cytokines, the cloning of G-CSF has provided the clinical application of rhG-CSF for neutropenic patients who may be induced by the treatment with anticancer agents. This symposium focused on above-mentioned items for an important aspect of neutrophil research.
Insights
Leukocytes are crucial for the immune system, engulfing microbes at infection sites. Research into chronic granulomatous disease (CGD) and NADPH oxidase has advanced understanding of leukocyte function and inflammatory responses.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Context:
- Leukocytes are vital for innate immunity, mediating the first line of defense against microbial invasion.
- The study of chronic granulomatous disease (CGD) has illuminated the role of NADPH oxidase in leukocyte function.
- Understanding leukocyte recruitment and function is critical for inflammatory and immune responses.
Purpose:
- To review recent advancements in neutrophil research, focusing on leukocyte function in infection and inflammation.
- To highlight the molecular mechanisms underlying leukocyte recruitment, adhesion, and phagocytosis.
- To discuss the clinical applications of cytokines like G-CSF in managing neutropenia.
Summary:
- Leukocyte bactericidal activity, initially described by Metchnikoff, involves phagocytosis and microbial killing at infection sites.
- Defects in NADPH oxidase in CGD patients have provided insights into superoxide generation and leukocyte function.
- Chemotactic factors like interleukin-8 (IL-8) and adhesion molecules (e.g., LFA-1) regulate leukocyte migration and interaction with endothelium.
- Cytokine networks, including G-CSF, are increasingly understood, leading to clinical applications such as rhG-CSF for neutropenia.
Impact:
- Advances in understanding leukocyte function, particularly NADPH oxidase and cytokine networks, have direct clinical implications.
- The research provides a foundation for developing novel therapeutic strategies for infectious and inflammatory diseases.
- This work underscores the importance of neutrophil research in both basic science and clinical practice.