Lecture Exam 4: Immune System Objectives

Provide a description of the two types of cells directly involved in adaptive immunity (T Cells). Be sure to include the type of immunity, where the cells are produced, where the cells mature, location of antigen they attack, sub-type of cells.

*Type: Cell Mediated Immunity *Produced: Bone marrow *Matured: Thymus *Location of Antigen: Infected body cells *Cells Produce: CD4+ (Helper T cells) and CD8- (Cytotoxic T cells)

Provide a description of the two types of cells directly involved in adaptive immunity (B cells). Be sure to include the type of immunity, where the cells are produced, where the cells mature, location of antigen they attack, sub-type of cells.

*Type: Humoral Immunity *Produced: Bone Marrow *Matured: Bone Marrow *Location of Antigen: Antigen in blood-body fluid *Cells Produce: Plasma cells: make antibodies and memory cells

Describe five different types of innate defense mechanisms found in the skin and mucus membranes which constitute the first line of defense against microorganisms.

-mechanical barriers: thick many layers of skin. mucous membrane are thinner layers that secrete mucous -acidic secretions: skin secretions: are acidic, ex. Sweat. Stomach: gastric juice -mucus: sticky mucous from respiratory/ digestive tracts trap pathogens -expel : body attempts to dilute or purge bacteria from body -lysosomes: enzymes destroys bacteria by breaking down cell walls. Ex. saliva, lacrimal fluid

Describe the five steps involved in phagocytosis of an antigen.

1) Phagocyte adheres to pathogens or debris. 2) Phagocyte forms pseudopods that eventually engulf the particles forming a phagosome. 3) Lysosome fuses with the phagocytic vesicle, forming a phagolysosome. 4) Lysosomal enzymes digest the particles, leaving a residual body. 5) Exocytosis of the vesicle removes indigestible and residual material.

List and describe the steps involved in the activation of Cell-Mediated Immunity: role of APCs, activation of helper cells, clonal selection of helper cells, activation of cytotoxic cells, clonal selection of cytotoxic cells.

1. APC's display antigens on MHCII (Exogenous antigen) 2. T helper cells bind (CD4 protein binds to MHC II, antigen to receptor on T cell) 3. Clonal selection of T helper cells-memory T helpers responsible for immunological memory ; T helper cells secrete cytokines: *interleukin-3 enhances phagocytosis & helpers further stimulate T Helper cells *Directly stimulates B cells *Interlukin-2 helps to activate T cyotoxic cells 4. Activation of cytotoxic T-cells (endogenous antigen)-CD8 binds to MHC1, antigen to T cell receptor 5. Clonal selection of cytotoxic T-cells; Cytotoxic T-cells destroy infected body cells (endogenous antigens): ▪ Binds to target cell ▪ Tc releases perforin ▪ Tc releases enzymes that degrade cell's DNA ▪ Tc detaches and binds to another infected cell

Define antigens and distinguish among self, endogenous and exogenous antigens.

Antigens: material that trigger an immune response •The antigens on your own cells are known as self-antigens •Endogenous: originate inside your body cells •Exogenous originates outside the cell and taken into by phagocytosis

List and describe the four mechanisms of antibody action.

Complement Activation: Destroy microbes by causing phagocytosis, cytolysis and inflammation Neutralization: Neutralized toxin. Prevent attachment of antigen to body cells Precipitation: Dissolves antigens Agglutination: Antigen-bearing cells, agglutinated microbes more easily phagocytized

Briefly explain the role of antigen presenting cells (APCs) in adaptive immunity.

Engulf antigenic determinants, present it to immune cells to find if B or T will be best to get rid of it.

Compare and contrast endogenous and exogenous antigen processing.

Exogenous: in fluids outside body cells •Antigen ingested by an APC (dendritic cell) by phagocytosis •Vesicle fuses with lysosome - Antigen broken into fragments •MHC II molecules made and fused with vesicle with antigen fragments •MHC II and antigen inserted into plasma membrane Endogenous: inside body cells •Antigen inserted into cell or can be made by the cell •Antigen digested into fragments in the cytosol •Antigenic determinant shipped to RER and bound with a MHCI made •MHCI and antigenic determinant inserted into plasma membrane Antigen presenting cell has MHC II on it

Explain the importance of immunological memory and the role vaccines play in adaptive immunity.

Immunological memory leads to a faster response on the second inoculation , memory cells help create a faster response, and do not meed co-stimulator cells for the second exposure. Memory cells are stored and ready to be activated, and vaccines help build up that immunological memory. Depending on types of vaccines there could be a shelf life on memory cells. Some vaccines need boosters because memory cells don't stay around as long for ex. whooping cough vaccine Different types of vaccines: -Live attenuated: inoculating someone with weakened bacteria: chicken pox vaccine -Inactivated: vaccines that are prepared with killed pathogens: polio vaccine -Subunit: vaccines that are prepared with parts of the bacteria/ virus -mRNA -Vector vaccines

Differentiate between the innate and adaptive body defenses and state the differences in the amount of time until a response is elicited and the general function.

Innate: born with these, non specific-reacts in the same way to every pathogen so rapid response Adaptive: develop/learn, specific to an antigen so slower to respond ~3-5 days initially, immunological memory-faster response AFTER initial exposure

Compare and contrast the phagocytic cells (macrophages, neutrophils, eosinophils, basophils in innate immunity

Macrophages- monocytes that leave the bloodstream and reside in body tissue Neutrophils- most abundant WBC, becomes phagocytic when they meet bacteria. Have a respiratory burst that creates hydrogen peroxide killing the ingested pathogens\bacteria. these migrate when needed Eosinophils- migrate and attack parasites Basophils- in the blood, help mediate inflammation (mast cells). Release histamines (vasodilates), heparin (anticoagulant)

Describe the role of cells (natural killers, phagocytic cells) and proteins (complement and interferons) in the antimicrobial defense mechanism.

Natural Killer: cells are policing cells that help to attack any body cell with abnormal cell surface proteins Phagocytic cells: circulate and migrate through tissues to ingest and destroy both microbes and cellular debris. Complement: proteins amplify the immune response Cell lysis, enhanced inflammation, neutralized viruses, enhanced phagocytosis due to opsonization, and clearance of immune complexes

Explain the three primary functions of inflammation after physical damage to the body. Be sure you can explain the steps involved in vasodilation and phagocyte mobilization

Phase 1: Inflammatory Response Healing of acute injuries begins with the acute vascular inflammatory response. The purpose of vascular changes is to increase blood flow to the local area, mobilize and transport cells to the area to initiate healing. Phase 2: Repair and Regeneration The second phase is characterized by new collagen formation. Phase 3: Remodelling and Maturation As healing progresses, the tissue continues to remodel, strengthen and improve its cellular organization. •During vasodilation mast cells produce inflammatory mediators which increase BV diameter •Inflammatory mediators cause vasodilation and increased permeability •Inflammatory mediators cause vasodilation and increased permeability, pain, and chemotaxis •Phagocytes mobilize to the area

Describe the process of activating and eliciting a response of the antibody-mediated (humoral) branch of the adaptive immune system. Be sure to include a brief description of the cells involved, the type of antigen processing (see above), activation of B cells, as well as the process of clonal selection.

•B cells are activated when they bind directly to an antigen(T helpers also involved) •Clonal selection produces memory cells(inactive storage of B cells) & plasma cells (secrete antibodies) •Plasma cells secrete antibodies: glycoproteins called immunoglobulins

Briefly explain the role of a fever in innate immunity.

•Fever is caused by pyrogens increasing the thermostat in the hypothalamus •Pyrogens reset the hypothalamus to a higher basal body temperature

Differentiate between MHC I and MHC II and be sure to state where they are located, their function and what binds to them and the cells they are located on.

•MHCI and MHC II are proteins that bind to forein material and display it on the outside of the cell •MHC I are found on surface of plasma breian, and on all cells, holds antigen or self proteins (endogenous). •They are responsible for processing antigens in sinde the body fluids •MHCII are found on surfaces of ANP, holds antigen (exogenous). They are responsible for processing antigens outside of body cells

List and describe the three primary features of adaptive immunity.

•Specific- cells and proteins respond individually told me a specific individual antigen •Systemic-body wide •Has a memory- immunological memory-exposure to an antigen is remembered buy specific word besides an antibody test allowing a more rapid and efficient response on subsequent exposures.

Explain the binding of a T helper cell and a T cytotoxic cell to an MHC complex - note any differences.

•T helper cells (CD4 proteins) bind to MHC II •T cytotoxic cells (CD8 proteins) bind to MHC I

Compare and contrast the mechanisms of action of T helper cells and T cytotoxic cells

•T helper cells/CD4 cells help to activate the cytotoxic T cells •Cytotoxic cells/CD8 will destroy infected body cells (need T helper cells to help activate them first)