Leukocyte Chemotaxins Types of chemotaxins C5a attracts neutrophils and monocytes Made by bacteria Peptide clipped off N-terminus(beginning with N formylmethionine during peptide maturation after protein synthesis Made by bacteria and nucleated blood cells Leucotrienes--lipid products of cell membrane metabolism BIOL 533 Lecture 6
BIOL 533 2 Lecture 6 Leukocyte Chemotaxins • Types of chemotaxins – C5a attracts neutrophils and monocytes – Made by bacteria • Peptide clipped off N-terminus (beginning with Nformylmethionine) during peptide maturation after protein synthesis – Made by bacteria and nucleated blood cells • Leucotrienes—lipid products of cell membrane metabolism
Leukocyte Chemotaxins Function of chemotaxins Enhance and direct motility of phagocytic cells To a limited extent oxidative metabolism of phagocytic cells BIOL 533 Lecture 6
BIOL 533 3 Lecture 6 Leukocyte Chemotaxins • Function of chemotaxins – Enhance and direct motility of phagocytic cells – To a limited extent, oxidative metabolism of phagocytic cells
3 Opsonization and Opsonins y General aspects Substances that enhance ability of phagocytes to ingest microbes Defend against presence of capsules and other microbial mechanisms that interfere with phagocytosis BIOL 533 Lecture 6
BIOL 533 4 Lecture 6 Opsonization and Opsonins • General aspects – Substances that enhance ability of phagocytes to ingest microbes • Defend against presence of capsules and other microbial mechanisms that interfere with phagocytosis
3 Opsonization and Opsonins y Types of opsonins Antibodies C3b component of complement Binds covalently to bacterial surface and is recognized by receptors on neutrophils, monocytes and macrophage Bacteria become bound to surface of phagocyte facilitating their uptake BIOL 533 Lecture 6
BIOL 533 5 Lecture 6 Opsonization and Opsonins • Types of opsonins – Antibodies – C3b component of complement • Binds covalently to bacterial surface and is recognized by receptors on neutrophils, monocytes, and macrophage – Bacteria become bound to surface of phagocyte facilitating their uptake
3 Opsonization and Opsonins y Types of opsonins, continued Mechanism White blood cell receptors for C3b At least 3--CR1, CR2, CR3(complement receptor) Children deficient in CR3 very vulnerable to bacterial infections BIOL 533 Lecture 6
BIOL 533 6 Lecture 6 Opsonization and Opsonins • Types of opsonins, continued – Mechanism • White blood cell receptors for C3b • At least 3—CR1, CR2, CR3 (complement receptor) • Children deficient in CR3 very vulnerable to bacterial infections