lymphatic23.pdf

11 The Lymphoid System and Immunity BSC 2086C ? J. Laborda Material herein intended for sole use of MCC BSC2086 students/faculty 2 Overview of the Lymphatic System ? Importance of the lymphatic system ? Two most important functions ? Maintain fluid balance in the internal environment ? Immunity ? Lymph vessels act as ?drains? to collect excess tissue fluid and return it to the venous blood just before it returns to the heart. Material herein intended for sole use of MCC BSC2086 students/faculty 23 Overview of the Lymphatic System ? Importance of the lymphatic system (cont.) ? Made up of: ? lymph, ? lymphatic vessels, ? lymph nodes, ? isolated nodules of lymphatic tissue, ? tonsils, thymus, and spleen Figure 22?1 An Overview of the Lymphoid System. Material herein intended for sole use of MCC BSC2086 students/faculty 4 Overview of the Lymphatic System ? Importance of the lymphatic system (cont.) ? Lymphatic vessels begin blindly in the intercelluar spaces of the soft tissues ? They do NOT form a closed circuit Material herein intended for sole use of MCC BSC2086 students/faculty Figure 22?2a Lymphoid Capillaries. 35 Overview of the Lymphatic System ? Importance of the lymphatic system (cont.) ? Transports tissue fluid, proteins, fats, and other substances to the general blood circulation Material herein intended for sole use of MCC BSC2086 students/faculty 6 Lymph and Interstitial Fluid ? Lymph ? Clear, watery appearing fluid found in the lymphatic vessels; closely resembles blood plasma in composition ? Interstitial fluid (extracellular fluid) ? Complex fluid that fills the spaces between the cells; resembles blood plasma in composition with a lower percentage of protein (< 7%) ? The major difference between interstitial fluid and lymph fluid is location Material herein intended for sole use of MCC BSC2086 students/faculty 47 Lymphatic Vessels ? Distribution of lymphatic vessels ? Lymphatic capillaries are slightly larger than blood capillaries ? The lymphatic capillary wall consists of a single layer of flattened endothelial cells ? When interstitial pressure is greater than the pressure inside the lymph capillaries, they are forced open allowing fluid to enter?when the pressure inside the lymph capillaries is greatest, the overlapping cells are forced closed ? Anchoring filaments containing elastic fibers help to hold the lymph caps in place ? Lymphatic networks form (branch and anastomose) freely Material herein intended for sole use of MCC BSC2086 students/faculty 8 Lymphatic Vessels ? Distribution of lymphatic vessels ? Lymphatic capillaries merge to form larger lymphatics and eventually form the main lymphatic trunks, the right lymphatic duct, and the thoracic duct Material herein intended for sole use of MCC BSC2086 students/faculty 59 Lymphatic Vessels ? Distribution of lymphatic vessels (cont.) ? Lymph from upper right quadrant empties into right lymphatic duct and then into right subclavian vein ? Lymph from rest of the body empties into the thoracic duct, which then drains into the left subclavian vein ? About how much lymph per day? ? 3-4 liters Material herein intended for sole use of MCC BSC2086 students/faculty 10 Material herein intended for sole use of MCC BSC2086 students/faculty 611 ? The thoracic duct originates in the abdomen as a dilation called the cisterna chyli. ?It is about 15-18 inches long, and receives it?s lymph from the right and left lumbar trunks and from the intestinal trunk. Material herein intended for sole use of MCC BSC2086 students/faculty 12 Lymphatic Vessels ? Structure of lymphatic vessels ? Similar to veins except lymphatic vessels have thinner walls, more valves, and contain lymph nodes ? The lymphatic capillary wall is formed by a single layer of thin, flat endothelial cells (simple squamous epithelial) Material herein intended for sole use of MCC BSC2086 students/faculty 713 Lymphatic Vessels ? Structure of lymphatic vessels (cont.) ? As the diameter of lymphatic vessels increases from capillary size, the walls become thicker and have three layers ? One-way Valves are present every few millimeters in large lymphatics and even more frequently in smaller lymphatics Material herein intended for sole use of MCC BSC2086 students/faculty 14 Figure 22?3 Lymphatic Vessels and Valves. Lymphatic Vessels 815 Lymphatic Vessels ? Functions of the lymphatic vessels ? Remove large substances and even particulate matter from interstitial spaces ? Lacteals absorb fats and other nutrients from the small intestine (lacteals are specialized lymphatic capillaries that carry dietary lipids into lymphatic vessels and ultimately into the blood. The presence of these lipids causes the lymph draining the small intestine to appear creamy white and is referred to as ?chyle?) Material herein intended for sole use of MCC BSC2086 students/faculty 16 Circulation of Lymph ? The lymphatic pump ? Lymph moves through the system in the right direction due to the large number of valves Material herein intended for sole use of MCC BSC2086 students/faculty 917 Circulation of Lymph ? The lymphatic pump (cont.) ? Breathing movements and skeletal muscle contractions establish a lymph pressure gradient, as they do with venous blood Material herein intended for sole use of MCC BSC2086 students/faculty 18 Lymph Nodes Material herein intended for sole use of MCC BSC2086 students/faculty 10 19 Lymph Nodes ? Structure of lymph nodes ? Lymph nodes are an oval-shaped structure enclosed by a fibrous capsule ? Nodes are similar to a biological filter Material herein intended for sole use of MCC BSC2086 students/faculty 20 Material herein intended for sole use of MCC BSC2086 students/faculty 11 21 Lymph Nodes ? Structure of lymph nodes (cont.) ? Once lymph enters a node, it moves slowly through sinuses to drain into the efferent exit vessel Material herein intended for sole use of MCC BSC2086 students/faculty 22 Lymph Nodes ? Structure of lymph nodes (cont.) ? Trabeculae extend from the covering capsule toward the center of the node Material herein intended for sole use of MCC BSC2086 students/faculty 12 23 Lymph Nodes ? Structure of lymph nodes (cont.) ? Medullary sinuses are lined with specialized cells (macrophages) capable of phagocytosis Material herein intended for sole use of MCC BSC2086 students/faculty 24 Lymph Nodes ? Locations of lymph nodes ? Most lymph nodes occur in groups ? They are found throughout the body, the picture shows the positioning of some of the major groups of lymph nodes ? (1) Mastoid and sub occipital nodes of the head; (2) Cervical lymph nodes of the neck; (3) Axillary lymph nodes under the arms; (4) Inguinal lymph nodes of the groin area; (5) Popliteal nodes behind the knee Material herein intended for sole use of MCC BSC2086 students/faculty 13 25 Lymph Nodes ? Locations of lymph nodes (cont.) ? An enlargement of these nodes is common in inflammation and malignant disease. As a result, palpation (feeling) of the neck, armpits, and groin area is an important part of clinical investigation Material herein intended for sole use of MCC BSC2086 students/faculty 26 Lymph Nodes ? Functions of lymph nodes: two distinct functions 1. Defense functions: filtration and phagocytosis ?lymph nodes filter out microorganisms (pathogens), debris, and 99% of antigens from lymph. Many of the pathogens and most of the debris will be phagocytosed. If overwhelmed, lymph nodes can become infected or damaged Material herein intended for sole use of MCC BSC2086 students/faculty 14 27 Lymph Nodes ? Functions of lymph nodes: two distinct functions (cont.) 2. Hemopoiesis ? lymphatic tissue is the site for the final stages of maturation of some lymphocytes and monocytes Material herein intended for sole use of MCC BSC2086 students/faculty 28 Material herein intended for sole use of MCC BSC2086 students/faculty 15 29 Lymphatic Nodules (mucosa-associated lymphatic tissue (MALT) ? Lymphatic nodules are egg-shaped masses of lymphatic tissue not enclosed by a capsule. ? Located in lymph nodes, and in numerous places in the lining of the GI tract, urinary and reproductive tracts, and respiratory airways. ? Maturation sites of B- lymphocytes (mature into antibody-producing plasma cells, or develop into memory B cells) Small Intestine Material herein intended for sole use of MCC BSC2086 students/faculty 30 Tonsils ? Type of lymphatic nodules ? Located under/inside the mucous membranes in the mouth and back of throat Material herein intended for sole use of MCC BSC2086 students/faculty 16 31 ?Palatine tonsils (2) are located on each side of the throat ?Pharyngeal tonsil (adenoid) (1) is located near the posterior opening of the nasal cavity ?Lingual tonsils (2) are located near the base of the tongue Tonsils Material herein intended for sole use of MCC BSC2086 students/faculty Figure 22?6b Lymphoid Nodules. 32 Tonsils ? Protect against bacteria that may invade tissues around the openings between the nasal and oral cavities Material herein intended for sole use of MCC BSC2086 students/faculty 17 33 Thymus single, bilobed organ located in the mediastinum Figure 22?8 The Thymus. 34 Thymus ? Location and appearance of the thymus (cont.) ? Thymus is pinkish gray in childhood; with advancing age, becomes yellowish as lymphatic tissue is replaced by fat Material herein intended for sole use of MCC BSC2086 students/faculty 18 35 Thymus ? Structure & Function of the thymus ? Pyramid-shaped lobes (2 of them) are subdivided into small lobules ? Each lobule is composed of a dense outer cortex (composed of maturing T cells & dendritic cells, epithelial cells, and macrophages) and an inner, less dense medulla (containing more mature T cells from cortex, epithelial cells, dendritic cells, and macrophages) ? The thymus also produces several hormones important to developoment/maintenance of immunological defenses Material herein intended for sole use of MCC BSC2086 students/faculty 36 Spleen ? Location ? in the left upper quadrant of abdomen, directly below diaphragm, above the left kidney and descending colon, and behind the fundus of the stomach Material herein intended for sole use of MCC BSC2086 students/faculty 19 37 Spleen ? Structure of the spleen ? Oval in shape ? About 5 inches long ? Attached to stomach by gastrosplenic ligament (See Fig. 22 ? 9) Material herein intended for sole use of MCC BSC2086 students/faculty 38 Spleen Structure (cont) ? Surrounded by fibrous capsule with inward extensions (trabecula) that divide the organ into compartments ? White pulp (has a high concentration of macrophages and dendritic cells) resembles lymphoid nodules ? Red pulp (contains, in part, macrophages and lymphocytes) contains a lot of red blood cells Material herein intended for sole use of MCC BSC2086 students/faculty 20 39 Material herein intended for sole use of MCC BSC2086 students/faculty 40 Spleen ? Functions of the spleen ? Defense: macrophages lining the sinusoids of the spleen remove microorganisms from the blood and phagocytise them ? Hemopoiesis: monocytes and lymphocytes complete their development in the spleen, RBCs are produced during fetal life Material herein intended for sole use of MCC BSC2086 students/faculty 21 41 Spleen ? Functions of the spleen (cont.) ? Red blood cell and platelet destruction: macrophages remove worn-out RBCs and imperfect platelets and destroy them by phagocytosis; also salvage iron and globin from destroyed RBCs ? Blood reservoir: pulp of spleen and its sinuses store blood Material herein intended for sole use of MCC BSC2086 students/faculty 42 Clinical Application The spleen is often damaged in abdominal trauma. A splenectomy may be required to prevent excessive bleeding. Material herein intended for sole use of MCC BSC2086 students/faculty 22 43 Overview of the Immune System ? The immune system protects against assaults on the body ? External assaults include microorganisms (e.g., protozoans, bacteria, and viruses) and some worms ? Internal assaults include abnormal cells reproducing and forming tumors that may become cancerous and spread throughout the body Material herein intended for sole use of MCC BSC2086 students/faculty 44 Organization of the Immune System ? The immune system is continually at work ? Two major categories of defenses ? Non-specific defenses ? Specific defenses ? Nonspecific and specific defenses operate together to provide resistance to infection and disease Material herein intended for sole use of MCC BSC2086 students/faculty 23 45 Organization of the Immune System ? Nonspecific Defenses ? Always work the same way ? Against any type of invading agent ? Specific Defenses ? Protect against specific pathogens ? Depend on activities of lymphocytes ? Specific resistance (immunity) ? Develops after exposure to environmental hazards Material herein intended for sole use of MCC BSC2086 students/faculty 46 Nonspecific Defenses ? Seven major categories of nonspecific defenses ? Physical barriers ? Phagocytes ? Immunological surveillance ? Interferons ? Complement ? Inflammatory response ? Fever Material herein intended for sole use of MCC BSC2086 students/faculty 24 47 Nonspecific Defenses ? Physical Barriers ? Keep hazardous materials outside the body ? Phagocytes ? Attack and remove dangerous microorganisms ? Immunological Surveillance ? Constantly monitors normal tissues ? With natural killer cells (NK cells) Material herein intended for sole use of MCC BSC2086 students/faculty 48 Nonspecific Defenses ? Interferons ? Chemical messengers released by activated lymphocytes, macrophages, and tissue cells infected with viruses that trigger production of antiviral proteins in normal cells ? Antiviral proteins ? Do not kill viruses ? Block replication in cell ? Complement (C) Proteins ? Form the complement system (composed of 11 specialized proteins) ? These proteins complement action of antibodies ? They ultimately punch holes in the bacterium and cause cell lysis Material herein intended for sole use of MCC BSC2086 students/faculty 25 49 Nonspecific Defenses ? Interferons ? Complement (C) Proteins ? Form the complement system (composed of 11 specialized proteins) ? These proteins complement action of antibodies ? They: ? Cause mast cells to release more histamine which causes inflammation ? Attract neutrophils and macrophages ? phagocytes ? Enhance phagocytosis in that the presence of complement in the plasma membrane of the invader makes it easier for macrophages to bond to the invader ? Destroy the invaders plasma membrane by ultimately punching holes in the invader causing cell lysis (similar to what perforin did from NK cells) Material herein intended for sole use of MCC BSC2086 students/faculty 50 Nonspecific Defenses ? Inflammation ? Triggers a complex inflammatory response (localized) (see page 795 for summary of what happens) (cardinal symptoms: swelling, redness, heat, and pain) ? Fever ? A high body temperature ? Increases body metabolism ? Accelerates defenses ? Inhibits some viruses and bacteria Material herein intended for sole use of MCC BSC2086 students/faculty 26 51 Nonspecific Defenses Figure 22?10 Nonspecific Defenses. Material herein intended for sole use of MCC BSC2086 students/faculty 52 Nonspecific Defenses Figure 22?10 Nonspecific Defenses. Material herein intended for sole use of MCC BSC2086 students/faculty Fig. 22-13 Histamine & heparin 27 53 Specific Defenses ? Specific Defenses ? Specific resistance (?Immunity?) ? Responds to specific antigens ? With coordinated action of T cells and B cells ? T Cells ? Provide cell-mediated immunity ? Defend against abnormal cells and pathogens inside cells ? B Cells ? Provide antibody-mediated immunity ? Also called humoral immunity ? humours are body fluids (Greek origin) ? Defend against antigens and pathogens in body fluids Material herein intended for sole use of MCC BSC2086 students/faculty 54 Specific Defenses ? Forms of Immunity ? Innate ? Present at birth ? Acquired ? After birth ? Active ? Antibodies develop after exposure to antigen ? Passive ? Antibodies are transferred from another source Material herein intended for sole use of MCC BSC2086 students/faculty 28 55 Specific Defenses ? Active Immunity (acquired active) ? Induced ? Through vaccines containing the pathogen?s antigens ? Naturally acquired ? Through environmental exposure to pathogens and thus their antigens Material herein intended for sole use of MCC BSC2086 students/faculty 56 Specific Defenses ? Passive Immunity (acquired passive) ? Naturally acquired ? Antibodies acquired from the mother ? Induced ? By an injection of antibodies Material herein intended for sole use of MCC BSC2086 students/faculty 29 57 Specific Defenses Figure 22?14 Forms of Immunity. Material herein intended for sole use of MCC BSC2086 students/faculty 58 Specific Defenses ? Four Properties of Immunity ? Specificity ? Each T or B cell responds only to a specific antigen and ignores all others ? Versatility ? The body produces many types of lymphocytes: ? each fights a different type of antigen Material herein intended for sole use of MCC BSC2086 students/faculty 30 59 Specific Defenses ? Four Properties of Immunity ? Memory ? Some active lymphocytes (memory cells): ? stay in circulation ? provide immunity against new exposure ? Tolerance ? Immune system ignores ?normal? (self) antigens ? (because they are NOT bonded to MHC proteins). Foreign antigens MUST be bonded to MHC proteins for recognition Material herein intended for sole use of MCC BSC2086 students/faculty 60 Specific Defenses ? The Immune Response ? Two main divisions ? Cell-mediated immunity (T cells) ? cell mediated means that the T cells directly attack (do the attacking themselves) the pathogen ? Antibody-mediated immunity (B cells) (humoral immunity) ? antibody-mediated means that the B cells indirectly attack by producing antibodies that attack the pathogen Material herein intended for sole use of MCC BSC2086 students/faculty 31 61 Specific Defenses Figure 22?15 An Overview of the Immune Response. Material herein intended for sole use of MCC BSC2086 students/faculty T Cells and Immunity ? Cell-mediated immunity (T cells) ? Cytotoxic T cells ? Function best in their attack against cells infected by viruses ? Responsible for cell-mediated immunity ? Helper T cells ? Stimulate function of T cells and B cells ? Suppressor T cells ? Inhibit function of T cells and B cells 62 Material herein intended for sole use of MCC BSC2086 students/faculty 32 T Cells and Immunity ? Antigen Recognition ? T cells only recognize antigens that are bound to glycoproteins (MHC proteins) embedded in plasma membranes ? MHC Proteins (Major Histocompatibility Complex) ? These are the membrane glycoproteins that bind to antigens ? There are Class I and Class II MHC proteins ? Different (unique) from person to person 63 Material herein intended for sole use of MCC BSC2086 students/faculty ? Antigen-Presenting Cells (APCs) ? APC?s present the foreign invader (one of it?s identifying antigens) to both helper T cells and cytotoxic T cells. This action helps to activate the cells. Once helper T cells are activated, they then complete the activation of cytotoxic T cells through ?Co- stimulation?. ? Bacteria require APC?s for presentation to the body ? Viruses can be presented with or without help from APC?s ? Phagocytic APCs ? Free and fixed macrophages (connective tissues) ? Kupffer cells (liver) ? Microglia (CNS) ? Non-phagocytic APCs ? Langerhans cells (skin) ? Dendritic cells (lymph nodes and spleen) 64 T Cells and Immunity Material herein intended for sole use of MCC BSC2086 students/faculty 33 T Cells and Immunity ? Antigen Recognition ? Inactive T cell receptors ? Recognize Class I or Class II MHC proteins ? Recognize a specific antigen ? CD Markers ? In T cell membranes ? Molecular mechanism of antigen recognition ? Specific CD markers bond to specific MHC proteins ? More than 70 types - designated by an identifying number (e.g., CD4, CD8) 65 Material herein intended for sole use of MCC BSC2086 students/faculty See Figures 22- 17 & 22-18 on pages 802-803 T Cells and Immunity ? Costimulation neccessary ? For a cytotoxic T cell (killer T cell) to be activated, it must be costimulated by a helper T cell ? It is costimulated by bonding to a stimulating helper T cell at a second bonding site ? This confirms the first signal 66 Material herein intended for sole use of MCC BSC2086 students/faculty See Figures 22- 17 & 22-18 on pages 802-803 34 Activation, Proliferation & Differentiation of Helper T Cells (CD4 cells) ? Receptor on CD4 (inactive helper T cell) cell binds to foreign antigen presented by a MHC-II protein embedded in an APC ? Proliferates & differentiates into population (clone) of TH cells and long-lived memory TH cells Activation, Proliferation & Differentiation of Cytotoxic T Cells (CD8 cells) ? Receptor on CD8 (inactive cytotoxic T cell) cell binds to foreign antigen presented by a MHC-I protein embedded in a viral filled body cell ? Co-stimulation from helper T cell ? prevents accidental immune response ? Proliferates & differentiates into population (clone) of Tc cells and memory Tc cells 35 T Cells and Immunity ? Cytotoxic T Cells ? Also called killer T cells ? Seek out and immediately destroy target cells Actions of Cytotoxic T Cells (Fig. 22 ? 17) 1. Release perforin: ? To destroy plasma membrane by punching holes 2. Secrete poisonous lymphotoxin: ? To destroy target cell 3. Activate genes in target cell: ? That cause cell to die 69 Material herein intended for sole use of MCC BSC2086 students/faculty T Cells and Immunity ? Slow Response of Cytotoxic T Cells ? Can take up to 2 days from time of first exposure to an antigen for cytotoxic T cells to reach effective levels ? Memory Tc Cells ? Produced with cytotoxic T cells ? Stay in circulation ? Immediately form cytotoxic T cells if same antigen appears again 70 Material herein intended for sole use of MCC BSC2086 students/faculty 36 T Cells and Immunity ? Suppressor T Cells ? Secrete suppression factors ? Inhibit responses of T and B cells ? Act after initial immune response ? Limit immune reaction to single stimulus 71 Material herein intended for sole use of MCC BSC2086 students/faculty T Cells and Immunity ? Helper T Cells ? Activated CD4 T cells divide into ? Active helper T cells (TH cells): ? secrete cytokines (e.g., Interleukin II) o Four Functions of Cytokines ? Stimulate T cell divisions » Result in production of memory TH cells » Accelerate cytotoxic T cell maturation ? Attract and stimulate macrophages ? Attract and stimulate NK cells ? Promote activation of B cells ? Memory TH cells: ? remain in reserve 72 Material herein intended for sole use of MCC BSC2086 students/faculty 37 73 B Cells and Immunity ? B cells develop in two stages ? First stage: Pre-B cells develop by a few months of age in the bone marrow ? Second stage: occurs in lymph nodes and spleen where they stay put ? In the presence of a foreign antigen, specific B cells become activated ? yet are initially on ?standby? - helper T cells then complete the activation of the B cell by bonding to antigens that are now associated with the MHC II proteins of the B cell) ? Most then differentiate into plasma cells that secrete specific antibodies (glycoproteins - normally found in the body), which in turn circulate in the lymph and blood to reach the site of invasion Material herein intended for sole use of MCC BSC2086 students/faculty see Fig. 22-20 74 B Cells and Immunity ? These B cell produced antibodies, traveling through the blood and lymph, attack pathogens or direct other cells, such as phagocytes, to attack them, or to neutralize or immobilize them ? Because they do not directly attack the pathogens themselves, they are classified as antibody- mediated immunity Material herein intended for sole use of MCC BSC2086 students/faculty 38 75 Material herein intended for sole use of MCC BSC2086 students/faculty B cells and Immunity 76 ? Five classes of antibodies [also known as immunoglobulins (a class of glycoproteins)] ? IgM, IgG, IgA, IgE, IgD ? IgM ? antibody inactive B cells synthesize and insert into their own plasma membranes; it is the predominant class produced after initial contact with an antigen (only ~5-10% found in the blood) ? IgG ? makes up about 75-80% of antibodies in the blood; predominant antibody of the secondary antibody response ? IgA ? major class of antibody in the mucous membranes, in saliva and tears ? IgE ? small amount; involved in allergic and hypersensitivity reactions, provides protection against parasitic worms ? IgD ? small amount in blood; precise function unknown but involved in activation of B cells B Cells and Immunity Material herein intended for sole use of MCC BSC2086 students/faculty 39 77 ? Antibody molecules produce antibody-mediated immunity within plasma ? Antibodies resist disease first by recognizing foreign or abnormal substances ? For example: Molecules called epitopes, which act as triggers for immune responses bind to an antibody molecule?s antigen-binding sites, which forms an antigen-antibody complex that may produce several effects ? One of these effects may be to set in action a series of events referred to as a ?Complement.? B Cells and Immunity Material herein intended for sole use of MCC BSC2086 students/faculty 78 ? Complement ? a component of blood plasma consisting of several protein compounds (~30); serves to kill foreign cells by cytolysis, causes vasodilation, enhances phagocytosis, and other functions ? Memory B cells ? Like memory T cells, remain in reserve to respond to next infection B Cells and Immunity Material herein intended for sole use of MCC BSC2086 students/faculty 40 79 Material herein intended for sole use of MCC BSC2086 students/faculty 80 Material herein intended for sole use of MCC BSC2086 students/faculty 41 81 STRESS, AGING, AND IMMUNITY DISORDERS RESISTANCE TO DISEASE LYMPHATIC SYSTEM Lymphatic System & Immunity VESSELS AND FLOW ORGANS AND TISSUES DEVELOPMENT NONSPECIFIC RESISTANCE IMMUNITY: SPECIFIC RESISTANCE -AIDS -Allergy -Autoimmunity -Infectious mononucleosis -Medical terms -Thymus -Nodes -Spleen -Tonsils -Lymphatic vessels -Lymph flow CytokinesAntigens -Thymus -Nodes -Spleen -Tonsils -Interleukins -Interferons -Lymphotoxin -Perforin Antibody-mediated Immunity (AMI) Cell-mediated Immunity (CMI) -B cells -Plasma cells -Antibodies (e.g., Ig)Self-recognition: Immunological tolerance Phagocytosis FeverInflammationSkin, mucosa Antimicrobial substances NK cells Second Line of DefenseFirst Line of Defense -T cells: cytoxic (Tc), helper (Th), memory -Mechanical factors -Chemical factors -Interferons -Complement -Transferrins -Chemotaxis -Opsonization -Adherence -Ingestion -Killing -Mechanical factors -Chemical factors Material herein intended for sole use of MCC BSC2086 students/faculty Jeffery A. Laborda The Lymphatic and Immune Systems and Resistance to Disease