Neutrophils are a type of white blood cell that are produced in the bone marrow at a rate of 8 million per minute and have a lifespan of 2-4 days. They play an important role in innate immunity by migrating to sites of infection and inflammation and phagocytosing bacteria and other pathogens. Neutrophils adhere to blood vessel walls and migrate through the tissues using selectins, integrins, and chemotaxis in response to bacterial products and inflammatory signals. During phagocytosis, opsonins coat pathogens to facilitate their recognition and ingestion by neutrophils through surface receptors. Once ingested, pathogens are destroyed through the respiratory burst and lytic enzymes within the phagolysosome.

1. INNATE IMMUNITY: NEUTROPHILS AND THEIR PRODUCTS

3. Greek Myelos = bone marrow Bursa Bone marrow

4. Act rapidily Incapable of sustained effort Act more slowly

7. NEUTROPHIL 8 x 10 6 /min Life span: 2-4 days Cannot divide Fine granular cytoplasm Segmented nucleus Two pools: circulating and sequestered in microvasculature

8. Direct movement of cells (leucocytes) under the influence of an external chemical gradient.

11. CHEMOTAXIS Bacteria products Integrins/selectins (gradient) 1 2 3 4 5 6

12. Rolling Adherence Emigration Selectin- mediated Integrin- mediated Inflammatory stimuli Chemotaxis Blood flow The stages of neutrophil adhesion and emigration from blood vessels. PMN

13. The proteins and their ligands engaged in neutrophil-vascular endothelial cell binding

15. Phagocytosis

16. ADHERENCE AND OPSONIZATION Opsonin (Greek > sauce). A molecule that facilitates phagocytosis by coating foreign particles (neutralizes –ve charges) Zeta potential - + C +++

17. Receptor for C Receptor for Ab ADHERENCE AND OPSONIZATION

18. Streptococcus agalactie Neutrophil

19. ADHERENCE AND OPSONIZATION

20. INGESTION AND PHAGOSOME FORMATION

21. PHAGOLYSOSOME

22. Neutrophil Activation

23. DESTRUCTION The Respiratory Burst O 2 Superoxide anion Hydrogen peroxide 1 3 4 5 2

24. LYTIC ENZYMES

25. SURFACE RECEPTORS

26. The Removal of Apoptotic Neutrophils