Cells and Cellular Activity of Immune System PDF

Chapter 3 Lecture No. 5: Cells and cellular activity of immune system: granulocyte and mononuclear cells By Gheyath K. Nasrallah, PhD, MT(AAB) 1  Origin and development of blood cells (hematopoiesi...

Chapter 3 Lecture No. 5: Cells and cellular activity of immune system: granulocyte and mononuclear cells By Gheyath K. Nasrallah, PhD, MT(AAB) 1  Origin and development of blood cells (hematopoiesis) Hematopoiesis is the formation and development of blood cells. This process depends upon hematopoietic stem cells (HSC). s of hematopoiesis: 2-8 weeks: fetal yolk sac onth to 5 months: fetal liver and spleen onths onward: bone marrow 2 Development of the immune system Neutrophil Eosinophil' s Stem cell T cell Basophils Granulocytes Myeloid Lymphoid progenitor progenitor NK cell Mast cell B cell Monocyte Macrophage Dendritic cell Plasma Cell  Response of pathogens, involving cross-talk among many immune cells, 4 Main cellular Components of the innate immune system Cell Functions Neutrophils Phagocytosis and extracellular killing Inflammation and tissue damage Macrophages Phagocytosis and intracellular killing Extracellular killing of infected or altered self targets Tissue repair (phagocytosis of dead cells) Antigen presentation for specific immune response Natural killer (NK) Killing of virus-infected and altered self targets and lymphokine activated killer LAK cells APC starts with macrophages and NK’s Apoptotic cells are cleaned by macrophages and Eosinophils, Killing of certain dendritic cells parasites and allergic reactions basophils and mast NK kills altered cells : infected and tumor cells cells. How do cells of the innate immune system recognize pathogens Recognition via Receptors (R): IgR : FcɤR, FcɛR Complement R Scavenger R Toll-like R (TLR) Mannose R 6  Complement and Ig  receptors Coating or opsonization: antibodyies or complement binds antigen bacterial surface  Phagocytes poses complement receptors and /or Fc region of certain Ab isotypes  Complement or Ig receptors 7  Opsonization by complement Opsonizati on Complement Complem (C3) ent receptor macrophag e 8 Opsonization by antibodies Anitbody (Ab) antibody dependent dependent cellular phagocytosis cytotoxicity ADCC Macrophage nutrophil, or 9 mast cell  Pattern recognition receptors (PRRs).  Macrophages, neutrophils, and dendritic cells (DCs) express a range of pattern recognition receptors (PRRs) that recognize PAMPs  PRRs interact with conserved microbial components called pathogen associated molecular patterns (PAMPs). 10  Pattern recognition receptors  PAMPs: (PRRs). Bacterial cell wall repetitive units within microbial structure that are distinct from molecular and cellular structure of higher organism, thus recognized as foreign http://www.hindawi.com/journals/ijmb /2010/124509/fig2/ 11  Examples of PAMPs: 1- peptidoglycan (PG) of bacterial cell wall 2- lipopolysaccharide (LPS) of Gram negative bacteria 3- lipteichoic acid of Gram positive bacteria 4- viral RNA and DNA (CpG) 5- microbial phosphocholine 6- microbial protein : protein amino acid sequence usually start formal- methionine (F-met) 12  Recognition of PAMPs A- Secreted pattern recognition molecules B- Membrane-associated PRRs C- Cytosol- associated PRRs-present in the 13  Secreted pattern recognition molecules  Acute phase response proteins: soluble pattern recognition molecules produce by the liver and secreted into blood Bacteria or stream virus 1- Mannose binding lectin (MBL)MB L proteins: Lectins are proteins that binds sugars. Examples: ficolins and surfactant Mannose sugar –Part protein A and D (SP-A, and SP-D) MBL posses lectin domains that of LPS or PG 14 interact with mannose residues of microbes. Secreted pattern recognition molecules- continue 2- C-Reactive Protein (CRP): bind to phosphocholine in microbial LPS. Activate phagocytosis Activate alternative complement pathway? CRP level in blood used as clinical marker of inflammation  (ESR) 15  Membrane associated PRRs 1- Macrophage mannose receptors: 2- Glucan receptors-in fungi 3- Scavenger receptors: microbial lipids. 4- Formylmethionine receptors: binds to bacterial protein 5- Toll like receptors http://content.edgar-online.com/edgar_conv_img/ Macropha (TLRs) 2007/11/02/0000950136-07-007421_IMG015.JPG 16  Toll-like receptors (TLRs) Cell membran e Exam questions http://www.cytographica.com/ from this par overheads/images/TLRs_med.jpg 17 Toll-like receptors (TLRs) Names as toll (Why).  Belongs to Immunoglobulin (Ig) superfamily receptors ? Expressed mainly on the surface of macrophage and DCs, but also other cells  15 sub classes (TLR-1 to TLR15): interact with surface material of virus, fungi and bacteria  Examples: TLR-1 (CD281), TLR-2 (CD282): Gram positive bacteria TLR-3 (CD283): dsRNA of some viruses  TLR-4 (CD284): LPS negative Bacteria  TLR-5 (CD285):bacterial flagellin, activated in certain cancers TLR-6: Bacterial lipoproteins binds to peptidoglycan Binding of TLRs to their Ligands mediate the 18 Transcription factors 19  Vedio : http://www.youtube.com/watch?v=iVMIZy -Y3f8 FIGURE 2.6. (A) Pattern recognition receptors called TLRs binding to molecules with specific pattern motifs expressed by various pathogens. (B) Soluble MB lectin binding to bacterial polysacchrides (terminal mannose residues in this case). Cytosol- associated PRRs  TLR expressed on endosomal vesicle in the cytplasm  e.g., TLR-3 binds to viral RNA and TLR-9 bid to bacterial DNA (rich in CpG motif)  Promote cytokine production: interferon-ɑ (IFN-ɑ and interferone-β (IFN-β) and IL-1B which promotes inflammation. 21 Cytosol-associated PRRs http://openi.nlm.nih.gov/imgs/rescale d512/1257453_ar1818-1.png 22  Damage-associated molecular pattern molecules (DAMPs)  Danger-associated molecular pattern molecules.  Enhance immune response to non- infectious agent such as denatured necrotic or tumor nuclear or cytosolic proteins (intracellular: reduced extracellular: oxidized form)  Tumor cell DNA and RNA (through TLR9)  Hsp, High mobility box associated with chromatin (HMB1),  S100: mitogenic calcium modulated protein 23  Cells of innate immune Systems Phagocytes: 1.Monocytes 2.Macrophages 3.Neutrophils 4.Dendritic cells 5.Mast cells Others: Basophils, Eosinophils, 24 Host Defense functions 1. Microbial killing 2. Antigen Presentation 3. Secretion of biologically active molecule 4. Clearance of dead tissue 25  Mononuclear phagocyte- Appearance and Monocytes structure: largest circulating blood cell They have a large, kidney-shaped nucleus" moth-eaten" appearance (holes). Location Monocytes spend only few days in the blood before migrating into the tissues, where they differentiate to become macrophages. Macrophages survive http://www.youtube.com /watch?v=VGsw7FEXye for several months to A 26 years in tissue  Phagocytes – macrophages  Appearance and structure: Nucleus: Large nucleus Cytoplasm: contains lots of Lysosomes Surface receptors: complement, Macrophage FcɤR , and TLR and others.  Location Circulate in the blood as Neutrophile monocytes (24 hours) before residing in the tissue as macrophage (months or years). In spleen (Macrophage), in liver (Kupffer cells), the pulmonary Source: Dr. Peter Darben, Queensland alveolar macrophage in lung University of Technology, used with(Dust cell), in brain (microglia and  Phagocytes – macrophages Figure 3-4 Electron micrograph of a Figure 3-5 Macrophages in macrophage culture. Note their elongated form, indicative of their motility. The cellular refractive bodies are erythrocytes that the 28 macrophages are phagocytosing  Phagocytes – macrophages Functions: 1. Phagocytosis: microbial killing : produce lactoferrin?, pyrogens?, interferons, complement.  Break down of tumor cells and damaged tissue. Link the innate and the adaptive immune response through: TLR: activation of macrophages through TLR mediate production of cytokines such as IL-1 and TNF-α that induce 29  Phagocytes – macrophages 2-Antigen presenting cell (APC): The fate of digested molecules: 1- exocytosis 2-presented on MHC molecule 1-macrophage ingests pathogens and foreign materials, break them down, and then present antigen fragments (epitopes) on their surfaces in the context of MHC-1 and MHC-II to T-cells to initiate the adaptive immune response. 2- During infection- T cell activate macrophage by secreting INF-ϒ and G-CSF 30  Phagocytes – Neutrophils Appearance and structure: Nucleus: multi-lobes (2-5 lobes ) known as polymorphonuclear cells (PMNs). Cytoplasm : contains three types of granules Surface receptors, Complement (C3) and FcɤR  Location: Circulate in the blood (45-75% of circulating leukocytes) unless Pus formation by attract to the tissue to deal with Neutrophils. infection Usually respond chemotaxis: bacterial or fungal components, 31 cytokines, complement Tertiary granules: Lactoferrin?, defensins Primary, or azurophilic granules (lysozyme or myeloperoxidase, ROS) Secondary or specific granules: caspase, hydrolytic enzymes 32 Phagocytes-Dendritic cells (DC) 1. Dendritic cells?? and macrophage: professional antigen (Ag) presenting cells. 2. Dendritic cells are present in tissues in contact with the external environment, such as the skin (Langerhans cells). 3. Once activated by antigen, they migrate to the lymph nodes where they interact with T- lymphocytes to initiate and shape the adaptive immune response 4. Present Ag on MHC-I and MHC-II Electron micrograph of DC 5. Co-stimulatory signals: B7 (CD80) bind to CD28, B7.2 (CD86) Phagocytes-Dendritic cells (DC) 6. Originate from myeloid or lymphoid (plasmocytoid) 7. Two different cell types: mDC: pDC: 6. Markers: 3 distinct markers 7. Cytokine: IL-12 (mDC) to activate T-cells and INF-α (pDC) to activate other macrophages 8- Can we isolate DC from peripheral blood? IL-4R &GM-CS: monocyte into premature DC INF-α: activated DC Electron micrograph of DC  Mast cells  Appearance and structure Nucleus: round Cytoplasm: cytoplasmic granules Release of preformed cytokines, chemokines, and histamine that increases vascular permeability, and Author: Salah Mecheri vasoconstriction that leads Institute Pasteur to anaphlactic shock if it is Dept of Parasitology, and Mycology sever. Paris, France FcɤR (CD16) and FcɛR (CD23) 36 http://www.embrn.eu/wiki/wiki-start/mast-c ells-in-innate-and-adaptive-immunity/ 37 38 39  Eosinophils  Appearance: Similar to neutrophils but larger Nucleus: bi-lobed nucleus Cytoplasm: lots of granules, stain with acidic dyes (eosin): acidophil – Major basic protein (MBP): Source: Bristol Biomedical Image Archive, Potent toxin for helminths used with permission (worms)  Location They are primarily found in the tissues (not lung or skin, esophagus), spending 8-12 hour in blood (1-3%).  Functions: Kill parasitic worms Allergic reaction (secrete histamines, IL-3, IL-5, GM-CSF) and leukotrines (anaphylaxis) Appearance and Basophils structure Nucleus: bilobed "S- shaped” Cytoplasm: they are named after their highly basophilic cytoplasmic basophilic granules. The granules contain heparin, histamine, chemotactic factors, and peroxidase. FcɛR receptor (receptor for IgE)  Similar to mast cells (see below) Important in ectoparsite infection such as ticks They produce IL-4 41  Natural Killer (NK) cells  Large granular lymphocytes (LGL): because they resemble lymphocytes in their morphology, except that they are slightly larger and have numerous granules.  Kill virus-infected or malignant cells  Identified by the presence of CD56 (Neural Cell Adhesion Molecule) & CD16 (FCɤR111) and absence of CD3 (present on the surface of T and B-lymphocytes) FcɤR receptor is important in ADCC  Activated by IL-12 and IFN-γ (produced by other leukocytes such as NKT-Natural killer t cells ) to become lymphokine activated killer (LAK) cells which is more  Lymphokine Activated Killer (LAK) cell IF N- ɤ kills kills IL12 transformed maligna and nt cells malignant cells Regulation of NK cell function KIR receptor FIGURE 2.5. NK-cell inhibitory receptors and killing.  Regulation of NK Cell Function How do NK and LAK cells distinguish a normal cell from a virus- infected or malignant cell? MHC I KIR KAR KAL No Killing Killing KIR a killer inhibiting receptor KAR: a killer activating receptor MCH-class 1: major histocompatability class-1: abundantly found in all normal cells however, malignant cells or infected cells express less MHC I.  K Cells T cell depends on  morphologically undefined MHC. NK cell the # MHC  Mediate ADCC (antibody- dependent cellular cytotoxicity)  have Fc receptor binds to IgG  recognize antibody coated targets  ADCC: could be NK cells (IgG), macrophages (IgG), eosinophils (IgE) or other Receptor - cells IgG in NK  Unusual lymphocyte Natural killer T-cell (NKT): ??? ɤɛ T cells: thymus and peripheral lymphoid organ ??? 47 48  Steps of phagocytosis: Neutroph ils lysoso bacte me ria 2 3 1. Chemotaxis: attraction to the site of infection( could be bacterial lipopolysacchraides, or cytokines present in the tissue, could be lipids) 2. Recognition and adherence 3. Engulfment 4-Phagosome or endosome formation 5-Phagosome-lysosome 4 5 (phagolysosome) fusion: phagoso phagolysos Granules or lysosome me Phagocytes – Neutrophils Phagocytosi s vidio: http://www.youtube.com/watch?v=I_xh-bkiv_c Steps of phagocytosis http://www.youtube.com/watch?v=7VQU28i tVVw&feature=related 50 Phagocytes function – Microbial killing 1-Oxygen independent: hydrolytic (proteases, lipazes,etc) enzymes and lysozyme 2- oxygen dependent (respiratory burst) : A-NADPH oxidase (PHOX): uses O2 to produce reactive oxygen species (ROS) such as superoxide anion (O2People - ), and Hydroxyl with a deficiency radical (OH.) and Hydrogen can not peroxide produce the ROSH leading to higher chances 2O 2 B-Myeloperoxidase: uses H2and of bacterial O2 fungal to oxidize infection chloride ions into hypochlorite ClO− (hypochloride) (the active component of 51  Phagocyte function: Ag Presentation and secretion of active molecules Exogenous Ags such as bacterial endotoxin activated macrophage ? INF- IL-1 ϒ (beta and specif G- ically CSF Peptid ) TNF-α e: 25 amino acids Continuation: 1- Exogenous Ags : B-cell bind to Ag in native status Fig: The two-way interaction between B cells and T cells provides the basis for the concept that, in certain autoimmune diseases, an amplification cycle might allow persistent immunopathology to arise from a minor 'trigger' factor. Such a trigger might initiate the cycle through events in either the B-cell or the T-cell compartment, including the stochastic generation of both B-cell receptors (BCRs) and T-cell receptors (TCRs). Edwards et al. Nature Reviews Immunology 6, 394–403 (May 2006) | doi:10.1038/nri1838  2- Endogenous Ags: Endogenous Ags are generated within a cell, could be: -viral proteins in any infected cell - foreign protein in any malignant cell Antigen processing Ag degraded into fragments (e.g., peptides) within the cell. ??? Ag peptide (up to 9-11 amino acids) displayed at the surface of the cell in the context of MHC-1 Ag then can be recognized by CD8+ T cells (cytotoxic) Vedio through TCR and CD8 receptor. : http://www.youtube.com /watch?v=dTb0iEUS1oA Infected cell is destroyed by  Structure and function of the MHC summary of the differences between class I and II MHC molecules All cells especially immune Immune system cells and some other cells system cells 11/05/2024 02:59 PM Intro.to path. 3 55  Acute inflammation  Inflammation is characterized by redness, heat, swelling, and pain(production of neuropeptides), organ dysfunction.  The primary objective of inflammation is to localize and eradicate the irritant and repair the surrounding tissue.  The inflammatory response involves the following three major stages: 1. Dilation of capillaries to increase blood flow. (comes from macrophages which produce cytoines that lead to structural changes in the epithelial cells) 2. Microvascular structural changes and escape of plasma proteins from the bloodstream. 3. Leukocyte transmigration through endothelium and accumulation at the site of injury. 56 Activated by sialyl – lewisX Acute inflammation P- Selectin: platelets CD6 2) Endothelial calls Chemotact ants Chemotact ants Sialyl-Lewis X: is carbohydrate structure on the surface of adhesion molecule of endothelial cells Video: http://www.youtube.com/watch?v=suCKm97yvyk 57 Acute Inflammation 58  Sepsis Figure 3-3 Two phagocytic cells have engulfed numerous 59  Sepsis  is a systemic inflammatory response syndrome (SIRS) due to infection Septic shock and death: Sepsis can cause vasodilation and organ dysfunction which may lead to death.  Sepsis is an infection-induced syndrome defined as the presence of two or more of the following features of systemic inflammation: Fever or hypothermia Leukocytosis or leukopenia Tachycardia and tachypnea (rapid breathing) Superanormal minute ventilations: the volume of air that can be inhaled (inhaled minute volume) or exhaled during one minute.  The most widely investigated cytokines (proinflamatory) are 60  Cellular communication Three protein family receptors: 1- Ig family: sIgs, TCR, MHC, and some CDs (such as CD4 and CD8). 2- Selectin family: expressed on both leukocytes and endothelial cells (L, E, and P- selectin). Examples: A- Endothelial cell adhesion molecule-1 or ICAM-1 intercellular adhesion molecule (CD54): bind to integrin LFA-1 (Lymphocyte function-associated antigen 1) B- Leukocyte adhesion molecule (LAM-1, Mel- 14) 61 Cellular communication-Continue 3- Integrin family: Integrin family members: interactions with cell surface ligands and extracellular matrix (ECM) components including fibronectin, collagen, and laminin.  Three subfamilies A- lymphocyte function-associated antigen-1 (LFA-1): is expressed on all leukocytes B- Mac-1(complment receptor CR3): found primarily on granulocytes and monocytes. C- Cp150, 95 granulocytes and monocytes.  Important in metastasis: migration of tumor cells 62  Disorders of neutrophils A. Noninfectious Neutrophil- Mediated Inflammatory Disease B. Abnormal Neutrophil Function C. Congenital neutrophils abnormalities 1. Chédiak-Higashi Syndrome 2. Chronic Granulomatous Disease (CGDs) 3. Complement Receptor 3 (CR3) 63  Disorders of neutrophils A. Noninfectious Neutrophil-Mediated Inflammatory Disease Tissue damage: due to leakage of granular materials: Neutrophils attempt to engulf large particles such as dust Chronic and persistent inflammation such as cystic fibrosis Autoimmune disease B. Abnormal Neutrophil Function  Patients with quantitative or qualitative defects of neutrophils have a high rate of infection Neutropenia (quantitative): marked decrease of neutrophils Severe defects in neutrophil function 64  Disorders of neutrophils C. Congenital neutrophils abnormalities: 12. Chronic Granulomatous Disease (CGDs) A genetically heterogeneous group of disorders of oxidative metabolism such as ROS production. Third of patients dying before age 7 years because of infections. 65  Disorders of neutrophils 4. Myeloperoxidase Deficiency Myeloperoxidase (production of H2O2) is an iron-containing heme protein responsible for the peroxidase activity characteristic of azurophilic granules. it accounts for the greenish color of pus. Mild-marked defect in bacterial and fungal clearance 66 Summary 69 A. Myeloid Cells I. Responsible for nonspecific response 2. Monocytes and macrophages a. In the peripheral blood, this cell is a monocyte; in the tissue, it is a macrophage. Tissue macrophages include alveolar macrophage, Kuppfer cells (liver), and astrocytes and microglia cells (nervous system). b. Functions I) Phagocyt.osis of invaders 2) Present immunogens to T helper cells, the first step in an immune response 3) Release cytokines (monokines) that affect other cells' activities c. Macrophages have major histocompatibility complex (MHC) class II, complement, and antibody Fe receptors on their surface. 3. G ranulocytes a. Neutrophils (polyrnorphonuclear cells or PMNs) I) 60-70% ofWBCs in circulation 2) Function: Phagocytosis and contributes to inflammatory response b. Eosinophils I) 1-3% of circulating WBCs 2) Mediate IgE allergic response c. Basophils l) 0-1.0% of circulating WBCs 3) Has receptors for IgE and granules responsible for allergic reactions D. Other cells that assist in the immune response a. Dendritic cells present antigen to T cells. b. Langerhans cells: Dendritic cell found in the dermis and squamous epithelia c. Mast cell: Granulocyte resembling basophil that contains many chemicals that affect 70 the immune response B. Lymphocytes a. 20-40% of circulating WBCs A. B lymphocytes (or B cells) I) 20% of circulating lymphocytes 2) Express surface molecules such as CD (cluster of differentiation) 19 and CD20. 3) After birth, B cells mature in the bone marrow. 4) B cells differentiate into either a plasma cell, whose role is to produce antibody, or a memory B cell. B. T Iymphocytes (or Tcells) I) 80% of circulating lymphocytes 2) Express surface molecules such as CD2 and CD3 3) Functions a. CTLs lyse host cells infected with viruses and tumor cells and also produce lymphokines. b. T cells stimulate (T helper cells) or suppress (T suppressor cells) other cells. 4) T cell maturation a) Pre--T cells begin in bone marrow and fetal Iiver. b) b) T cells go to the thymus to mature C. NK cells are slightly larger than T or B cells and have cytoplasmic granules. 71 Inflammation l. Sequenced events following tissue damage that protect the host from foreign invaders and attempt to minimize tissue damage 2. Increased vascular permeability a. Upon injury, capillaries, arterioles, and venules are dilated to increase blood flow to the site of the injury. b. Because of increased vascular permeability, fluid moves from the circulation to the space around the injury, bringing fibrinogen and PMNs to the injury site. 3. Migration of neutrophils a. After the injury, chemotaxins and endothelial activating factors are released. b. PMNs adhere to activated endothelial cells. c. PMNs move between the endothelial cells to the site of tissue damage by a process called diapedesis. d. Chemicals are released and more PMNs are released from the storage pool. and the injury site is flooded with PMN 4. Migration of mononuclear cells a. The macrophages release IL-1, which attracts monocytes, macrophages, and lymphocytes to the injury site. b. About 4 hours after the injury, mononuclear cells migrate lo the site of damage. 72 5. Cellular proliferation and repair: Fibroblasts help repair the