1. System which launches fight against infections
The Lymphatic System
System which launches fight against infections

2. Lymphatic System
The major components of the lymphatic system are lymphatic vessels, lymph, lymph nodes, and some other lymphatic organs
Lymphatic vessels carry lymph, a colorless liquid, throughout the body. Along lymph vessels are small bean-shaped glandular nodules called lymph nodes.
Other lymphatic organs are:
Tonsil: clusters of lymphatic tissues just under the mucous membranes that line the nose, mouth, and pharynx.
Spleen: it is similar to a lymph node in shape and structure but it is much larger.
Thymus: a soft organ with two lobes that is located
anterior to the ascending aorta and posterior to the sternum.
Peyer patch: lymphoid tissue on the visceral surface of the small intestine.

3. Lymphatic System Primary Lymphoid Organs Secondary Lymphoid Organs
Bone marrow and Thymus
Secondary Lymphoid Organs
Spleen, tonsils, Peyer’s patches
Lymphatic system, upper respiratory system and muscular system ALL contain lymphatic vessels

4. Lymphatic Vessels
Lymphatic vessels carry excess fluid from tissues and return it to the bloodstream.
Have flaplike valves that help prevent backflow of lymph
Vessels lead to lymph nodes
After leaving the nodes, the vessels merge to form lymphatic trunks

5. Lymphatic Capillaries
Thinned walled capillaries which allow fluid to enter.
Fluid inside is called “lymph”
Lacteals: lymphatic capillaries located in lining of small intestines which absorb fat and transport them to venous circulation

6. Lymph nodes and ducts
The right lymphatic duct drains lymph from the upper R side, whereas the thoracic duct drains lymph from the rest of the body.
Lymphatic capillary
Lymphatic vessel
Lymph node
Lymphatic trunk
Collecting duct
Subclavian vein

7. Lymph nodes Glands which are located along the lymphatic pathways
Contain large #s of lymphocytes and macrophages
Located in neck, thoracic cavity, armpit (axillary), abdomen, pelvic area, inguinal area and supratrochlear nodes (where is this???)
2 functions: filtration and providing lymphocytes and macrophages for immunity
Do not trap wbcs but they do trap bacteria, and toxins

8. The body’s defense system
Immunology
The body’s defense system

9. Terminology
Immunology: the study of how body components respond and interact
Immunoglobulins: class of proteins that make up antibodies
Phagocytosis: process where cells engulf and destroy foreign particles such microorganisms or damaged cells. Macrophages and segmented neutrophils are the most important phagocytic cells

10. Terminology
Immunogenicity: the degree to which an antigen elicits an immune response
Immunogen: antigen that stimulates an immune response
Soluble antigen: free floating antigen recognized by B cell receptors

11. Terminology
Epitope: the small piece of an antigen that is bound by an antibody or a T cell receptor
Chemotaxis: release of substances which attract phagocytic wbc to bacteria. Cells move from an area of low to high concentration of chemokines.

12. Immune System
Immune System: cells in our bone marrow, thymus, and the lymphatic system of ducts and nodes, spleen, and blood that function to protect us.
Function is to recognize self from nonself and to defend the body against nonself.

13. Lines of Defense 1st line of Defense Non Specific Responses
Innate or inborn
General response which protects us daily
Non Specific Responses
Inflammation
Phagocytosis
Physical barriers
Chemical barriers

14. Immune System 1st line of defense: Skin and mucosal membrane surfaces
Secretions: mucous on membranes in nose trap microorganisms and are secreted through sneezing. What other secretions can you think of?
Tears, saliva, ear wax, sweat, production and elimination of urine
Phagocytic wbc in the mucous membrane

15. Immune System 1st line of defense continued:
Normal flora deter penetration of microorganisms
pH of body fluids such as gastric juices
Cilia movement helps protect the respiratory tract
The enzyme lysozyme which is found in tears and saliva attacks and destroys the cell wall of susceptible bacteria especially some gram positive bacteria

16. Immune System Non specific cellular and chemical response
Fever production resulting from pyrogenic secretions from pathogens
Interleukin 1 produced resulting from stimulated macrophages.
Polypeptide secreted by macrophages, enhance T cell activation and activity
Phagocytosis: process of surrounding and engulfing foreign matter.
Antibodies coating an invading microbe for phagocytosis is called opsonization.

17. Activation of the Complement System
Activation of complement proteins
Opsonization: enhancing phagocytosis of Ags
Chemotaxis: attracting macrophages and neutrophils
Lysis: rupturing membranes of foreign cells
Clumping of Ag bearing agents
Altering the molecular structure of viruses

18. Inflammatory Response
Involves granulocytes such as basophils and eosinophils.
Mast cells are activated during an allergic reaction and release histamine
Delayed hypersensitivity is also called Cell Mediated response

19. Immune Responses 2nd line of Defense Specific Responses Specific
Production of Abs in response to Ag
Specific Responses
Associated with Ag and Ab reaction
Ab response occurs after exposure to Ag
Ab may neutralize, kill, or cause clumping of foreign microorganisms
Complement system also works w/Abs to destroy the invader
Complement system is a group of proteins produced in the liver, circulating in the plasma and enhance the work of Abs

20. Types of Immunity Types of Immunity Example Active natural immunity
Having a disease like the mumps
Active artificial immunity
Receiving a vaccination like (MMR)
Passive natural immunity
Abs produced by the body itself or received from mom
Passive artificial immunity
Injection of antibodies

21. Natural Immunity Also known as innate (inherited) immunity
Mechanism which kicks in after bacteria gets past the first lines of defense
Natural immunity is a non specific mechanism

22. Natural Immunity Components of Natural Immune System
Cellular components
Mast cells
Neutrophils: most abundant and 1st to arrive
Macrophages
Humoral (fluid)
Complement
Lysozyme
Interferon

23. Leukocytes Type Function Polymorphonuclear (granulocytes) Phagocytosis
Neutrophils
Phagocytosis, most active and voracious
Eosinophils
Allergic response
Basophils
Release histamine (so do mast cells)
Monocytes
Become macrophages and phagocytes
Macrophages
Lymphocytes
T Lymphocytes
Cell mediated immunity
B Lymphocytes
Humoral immunity
Plasma cells
Antibody production

24. Effector Cells
Plasma cells: derived from lymphocytes (white blood cells) and are the cells which secrete antibodies. They live a short time and are constantly being replaced.
Macrophages: derived from monocytes (wbc) w/primary function of phagocytosis

25. Adaptive Immunity Also known as acquired immunity
Active immunity can leave the host w/specific immunologic memory which allows the host to respond more effectively if re-infection with the same microorganism occurs

26. Specific Immune Response
Primary Immune Response: 10 to 17 days after initial exposure to Ag. Selected lymphocytes generate a maximum effector cell response.
While effector cells are developing an infected person may become ill but eventually the symptoms of the illness disappear as Abs and effector T cells clear antigens from the body.
Secondary Immune Response: later exposure to the Ag that results in a much faster (2-7 days), much faster, and more prolonged response by Abs and effector T cells

27. Immunoglobulin Structure
Composed of glycoproteins
4 protein chains held together w/ disulfide bonds
Fc region: constant region dictates the type of immunoglobulin A, E, D, M, or G
Fab portion: antigen binding region of the Ab. This region is highly diverse so that the variety of antigens recognized by these receptors is extremely numerous
Heavy chains
Light chains

28. Immunoglobulin Structure
Composed of 2 identical
Heavy chains and 2
identical light chains
Constant regions are located on both the light and heavy chains
The very end of the variable Regions is called the hypervariable as that is the region where the amino acid sequencing varies the most

29. Antibodies Variable region is what determines the antigen specificity
The constant region (Fc) is what determines the antibody immunological class or isotype (A,E,M,G, D)
Antibodies do not destroy antigens directly
Neutralize
Target for elimination
Agglutination, precipitation, complement fixation

30. Antibodies
IgM: first type of antibody secreted during a primary immune response (promotes agglutination or clotting)
IgG: major type of antibody secreted during a secondary immune response
IgE: type most associated with allergic reactions (promotes release of histamine)
Students need to know these facts

31. Antibodies
IgA: this is the antibody found in most abundance in bodily secretions such as saliva and mother’s milk
IgD: this antibody serves as a B cell surface receptor.
Soluble antibodies are involved in the following
Cause clotting
Can bind active sites on toxins
Tag foreign microbes for destructions
Be sure students know these facts!

32. Antibodies IgM and IgD are the first antibodies expressed by a B cell
Each B cell has ~ 100,000 IgM or IgD receptors on its surface
These antibodies can bind free Ags whereas T cell receptors can only bind to Abs when they are presented by Ag presenting cells (discussed later)
IgM and or IgD serve as B cell surface receptors so anytime you hear B cell receptor your first thought should be IgM and or IgD

33. Antibodies
Binding the IgM or IgD on the B cell surface provokes a primary immune response resulting in secretion of IgM, B cell division, and clonal expansion
Secretion of the IgM Abs stimulates the activation of the complement system
IgG Abs are then produced and promote phagocytosis
Clonal expansion: an activated B cell makes multiple exact duplicates (clones) that recognize the Ag that is bound and thus stimulated the activation of the original B cell
IgM production triggers the complement system activation
IgG production triggers phagocytosis

34. Antibody Response Graph

35. B Cell Maturation Stem cell Pro- B cell Pre B cell
Immature B cell mature B cell
During this time of development the Ab/Ag specificity is being determined through a process of random genetic recombination. Also undergoes a process of negative selection to screen for self versus non self molecules. During the immature B cell stage: if the antigen receptor matches with a self antigen the cell dies by apoptosis called Clonal Deletion

36. B Cell Maturation and Function
When antigen binds to the B cell receptor, the B cell is activated and begins to undergo clonal expansion, which results in the proliferation of exact duplicates of the original B cell.
When B cells are mature the must undergo a process to determine self tolerance. This process is Ag dependent.

37. Humoral Immunity Summary
Involves the production of Abs that circulate in the blood and lymph to defend against free bacteria, toxin, and viruses
Involves B cells that eventually differentiate into plasma cells or memory cells
Also requires the use of Helper T cells and certain cytokines such as IL-2
Plasma cells produce antibodies while memory cells wait for re-exposure
Antibodies tag foreign microbes for destruction through several processes
B cells mature and produce plasma cells (short lived) and memory cells (long lived)

38. Cell Mediated Response Overview
Involves direct killing of infected cells via TC cells
Does not involve the production of Abs
Requires both the activation of TH cells and TC cells
Some cells will become effector cells and some cells will become memory cells to wait for re-exposure
Most important cell is the TH cell
Overlaps with Humoral Response

39. T Lymphocytes Originate in the bone marrow but mature in the thymus
Stored in the secondary lymphatic tissue
Basis for Cell Mediated immunity
Lifespan: resting 1-3 weeks, activated 3-4 days, memory years/lifetime
Respond to specific Ag and cancer cells
Do not produce Abs
2 Primary types: cytotoxic and helper T cells

40. T Cell Maturation Stem Cell Pro T cell Pre T cell
Double positive T cell Double positive alpha beta TCR T cell Single positive T alpha beta TCR cell
During this time of development T cell receptor (TCR) specificity is being determined
Undergoes process of both positive and negative screening for productive gene arrangement, self versus non-self molecules, and appropriate CD surface protein molecules
CD 8 = Cytotoxic T cell, CD 4 = Helper T cell

41. Stem Cell differentiation
Stem cells originate in the bone marrow

42. Antigens Elicit an immune response 2 general types exist
Exogenous: foreign from outside the host
Endogenous: foreign from within the host
Viruses, bacteria, fungi, protozoa, and parasites are all antigens
Antigenic determinants = epitope

43. Antigens
Chemical composition are proteins and large polysaccharides (carbs)
Proteins make the best immunogens due to their high MW and structural complexity
Polysaccharides (carbs or sugars) are OK immunogens but their small size make them less effective than proteins

44. Antigens
Lipids are inferior antigens because of their relative simplicity and lack of structural stability
Nucleic acids are poor Ag due to lack of molecular flexibility and rapid degradation

45. Antigen Receptors
The way that B cells and T cells recognize specific molecules and trigger an immune response
Plasma membrane bound
All antigen receptors on a B cell or T cell have the same specificity
Determined by random genetic events
Occurs before any contact w/foreign antigen is made
Allows for an enormous variety of B and T lymphocytes

46. Autoimmunity
Immune system fails to distinguish self from non self producing autoantibodies and cytotoxic T cells that attack and damage the body’s tissues
May be caused by a virus replicating within a host cell or faulty T cells or antigen which closely resembles self Ag (example strep infection in heart valves)

47. Autoimmunity diseases and conditions
Cancer of the lymph nodes: when lymphocytes undergo a mutation and multiply out of control
Rheumatoid arthritis: involves the joints, RF factor is test method
Grave’s disease: hyperthyroidism, affects young women, goiter is common side effect as well as exophthalmos (protrusion of the eyes)
Pernicious anemia: mucous lining of stomach does not secrete protein called intrinsic factor which is needed for B12 absorption resulting in anemia
HIV infection: reverse transcription coverts viral RNA into DNA