BIOT 307: MOLECULAR IMMUNOLOGY

1. BIOT 307: MOLECULAR IMMUNOLOGY Cells and Organs March 7-9, 2011

2. IMMUNE CELLS • B lymphocytes • T “ • NK • Macrophages • Dendritic Cells Antigen Specific Antigen-presenting cells (APCs), non-specific • characteristic (See Fig. 2-2) • antigen receptors - B, T, NK • cell surface markers – all • functions - all

3. NATURAL KILLER (NK) • Large granular lymphocytes • Lack cell-surface markers like B and T cells, pattern recognition markers (PRRs), Ig or TCR gene rearrangements • Positive for • FcR(CD16)  receptor for binding to Fc of Ig • Activated by cytokines (IL-2, -12, -15, -18) and CCL5 and migrate to inflamed or tumor tissue • Lymph nodes, peripheral blood, spleen and liver

4. NATURAL KILLER (NK) • Influence specific acquired IR • Secrete IFN-γ and TNF-α  neutrophil, macrophage (Φ) activation • Activation  cytokine secretion that activates NK cells • Killing • Tumor cells • Cells infected by intracellular pathogens, e.g., viruses

5. NATURAL KILLER (NK) T CELLS • Killing • Direct: recognize altered MHC I, i.e., its lack, on target cells • Two receptor superfamilies • Inhibitory • Activating

6. NK: Killing by Antibody Dependent Cellular Cytotoxicity (ADCC) Killing: Indirect • Fc portion of Ab bound to Ag on target cell binds to FcR on NK • Fas on target cell binds to Fas ligand on NK • Release of perforin and granzymes

7. ADCC FUNCTIONS IN MANY CELLS • NK • Eosinophils • Macrophages • Monocytes • neutrophils

9. IMMUNE CELLS • B lymphocytes • T “ • NK • Macrophages • Dendritic Cells Antigen Specific Antigen-presenting cells (APCs), non-specific • characteristic (See Fig. 2-2) • antigen receptors - B, T, NK • cell surface markers – all • functions - all

10. MACROPHAGE (Φ) = major scavenger ROUTE 1: monocyte into circulation  inflamed tissues  inflammatory Φ and DCs ROUTE 2: Monoblast  promonocyte  monocyte  tissue  tissue (resident) macrophages (Φ) – different in different tissues .

11. MACROPHAGE (Φ) large quantities in the spleen, lymph nodes, alveoli, and tonsils; 50% found in the liver as Kupffer cells In tissue 2-3 mo..

12. MACROPHAGE INGESTING YEAST CELL

13. MACROPHAGE FUNCTIONS Accessory Secretory Effector Regulatory

14. MACROPHAGE FUNCTIONS • Accessory: Encounter and internalize Ag • Endocytosis • Phagocytosis ROUTE: APC amplifiers Cell surface receptors recognize Ag  ingestion  Ag processing in lysosomes  cell surface presentation of peptides to T cells  activated - activate specific immune response

15. MACROPHAGE • Varied and prolific secretory abilities • Pro-inflammatory cytokines • Attractants for neutrophils, immature dendritic cells, natural killer cells, and activated T • Pro-apoptotic factors • Chemokines, cytokines, lytic enzymes, complement components, oxygen radicals, NO, bioactive lipids, interleukins 1, IL-12, TNF-α and growth factors, self-activators.

16. MACROPHAGE ACTIVATION • Stimulated by Th cytokines • Inflammatory promoting cytokines • Bacterial cell wall components – lipopolysaccharide (LPS) • IFN-γ further activates Φ  better functioning • Fully activated • Larger, ruffled,  gene expression of effector molecules

18. MACROPHAGE ACTIVATION

19. NUMEROUS EFFECTOR CELL FUNCTIONS • Ag presentation • Kill microorganisms, tumor cells • Make Φ cytokine and chemokine production • Activate T cells

21. Notes for slide on previous page • Effector function of phagocytosis and killing of phagocytosed microbe • Reactive oxygen intermediates (ROIs) produced by phagocyte oxidase from oxygen • Nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) from arginine lysosomal enzymes • Other effector functions: • produce cytokines of innate immunity: TNF, IL-1, • Chemokines produce growth factors helping tissue remodeling and enhance antigen presentation by  increasing MHC molecules and costimulators

22. MACROPHAGE REGULATORY ROLES • Control IR • T-cell proliferation • Cel-cell contract • Monokines • Suppress lymphocyte proliferation • IFN-γ • Prostaglandins • Reactive oxygen species • NO

23. MACROPHAGE ROLES: IMMUNITY & INFLAMATION • inflammation and fever • lymphocyte activation • tissue reorganization • tissue damage • microbicidal activity • tumoricidal activity

24. Some bacteria subvert • Φ function • Receptor-mediated recognition • Phagocytosis • movement into lysosome • Perturb • ROS synthesis • RNI • Acidification • Ag processing • Ag presentation • Signaling

25. LEGEND FOR FIGURE ON PREVIOUS PAGE: Macrophages = sentinels and first line of defense against infection. Bacterial pathogens have subvert Φ function (in dark blue). Microbes can interfere with receptor-mediated recognition, phagocytosis and trafficking of bacteria to degradative lysosome. Bacteria that enter Φ avoid destruction by perturbing the signaling that is required for the production of reactive oxygen intermediates (ROIs), reactive nitrogen intermediates (RNI) and acidification (H+). Interfering with Ag processing or presentation prevents Φ from alerting other cells to infectious agent. Bacterial pathogens have several mechanisms for interfering with kinase and lipid signaling within infected Φ. Perturbation of Φ signaling: alter cell survival, transcription and secretion of soluble cytokines that recruit cells coordinate their responses to clear the microbe.

26. MACROPHAGE FUNCTIONS