Lecture 2a. OVERVIEW Adaptive immunity.pptx

adaptive immunity

1. Overview of the Immune System Immune System Adaptive immunity Delayed response to specific antigen B-lymphocytes (humoral immunity) T-lymphocytes (cell-mediated immunity) Plasma cells (synthesize and release antibodies) Physiologic responses (e.g., inflammation, fever) Chemicals (e.g., interferon, complement) Cells (e.g., macrophages, NK cells) Skin and mucosal Membranes & barriers (prevent entry) Immediate response to wide array of substances Innate immunity Nonspecific internal defenses

2. A typical immune response INNATE IMMUNITY Rapid responses to a broad range of microbes ACQUIRED IMMUNITY Slower responses to specific microbes External defenses Internal defenses Skin Mucous membranes Secretions Phagocytic cells Antimicrobial proteins Inflammatory response Natural killer cells Humoral response (antibodies) Cell-mediated response (cytotoxic lymphocytes) Invading microbes (pathogens) Complement

3. TWO DIVISIONS OF THE ADAPTIVE IMMUNITY The efforts of the WBCs known as phagocytes and T-cells is called the cell-mediated immune system. Protective factor = living cells Phagocytes – eat invaders T-cells – kill invaders

4. The other half of the immune system is called antibody-mediated immunity/humoral meaning that is controlled by antibodies TWO DIVISIONS OF THE ADAPTIVE IMMUNITY

5. Most infections never make it past the first and second levels of defense Those that do, trigger the production and release of antibodies Proteins that latch onto, damage, clump, and slow foreign particles Each antibody binds only to one specific binding site, known as an antigen Antibodies

6. Antibody Production WBCs gobble up (eat up a large amount of something hurriedly and noisily) invading particles and break them up They show the particle pieces to T-cells, who identify the pieces and find specific B-cells to help B-cells produce antibodies that are equipped to find that specific piece on a new particle and attach

7. Immunity New particles take longer to identify, and a person remains ill until a new antibody can be crafted Old particles are quickly recognized, and a person may never become ill from that invader again. This person is now immune.

8. What is immunity? Resistance to a disease causing organism or harmful substance Two types Active Immunity Passive Immunity

9. Active Immunity You produce the antibodies (in humoral) or (effector T-cells in C.M.I) Your body has been exposed to the antigen in the past either through: Exposure to the actual disease causing antigen – You fought it, you won, you remember it (Natural) Planned exposure to a form of the antigen that has been killed or weakened – You detected it, eliminated it, and remember it (Artificial) What is this second type of exposure called?

10. Vaccine Antigens are deliberately introduced into the immune system to produce immunity (Artificial Active immunity) Because the bacteria has been killed or weakened, minimal symptoms occur Have eradicated or severely limited several diseases from the face of the Earth, such as polio and smallpox

11. How long does active immunity last? It depends on the antigen Some disease-causing bacteria multiply into new forms that our body doesn’t recognize, requiring annual vaccinations, like the flu shot Booster shot - reminds the immune system of the antigen Others last for a lifetime, such as chicken pox

12. Passive Immunity You don’t produce the antibodies (Passive immunity ) A mother will pass immunities on to her baby during pregnancy (natural passive immunity) - through what organ? These antibodies will protect the baby for a short period of time following birth while its immune system develops. What endocrine gland is responsible for this? Lasts until antibodies die Or one can receive preformed antibodies prepared in a laboratory setting (artificial passive immunity) Placenta Why doesn’t the mother just pass on the WBCs that “remember” the antigens?

13. Immune Disorders ~Allergies~ (Immunology part 3) Immune system mistakenly recognizes harmless foreign particles as serious threats Launches immune response, which causes sneezing, runny nose, and watery eyes Anti-histamines block effect of histamines and bring relief to allergy sufferers

14. Acquired Immune Deficiency Syndrome (Immunology part 3) Caused by the Human Immunodeficiency Virus Discovered in 1983 Specifically targets and kills T-cells Because normal body cells are unaffected, immune response is not launched

15. AIDS ~The Modern Plague ~ (Immunology part 3) The HIV virus doesn’t kill you – it cripples your immune system With your immune system shut down, common diseases that your immune system normally could defeat become life-threatening Can show no effects for several months all the way up to 10 years

16. What is an antibody? Produced by Plasma cell (B-lymphocytes producing Ab ) Essential part of adaptive immunity Specifically bind a unique antigenic epitope (also called an antigenic determinant) Possesses antigen binding sites Members of the class of proteins called immunoglobulins

17. What does an antibody look like ? 2 identical heavy chains 2 identical light chains Each heavy chain – has a constant and a variable region Each light chain has a constant and a variable region H H L L Constant region Variable region

18. Antibody: structure and function Fab – fragment antigen binding Fc - Fragment constant

19. Antibody: Fab Fab region Variable region of the antibody Tip of the antibody Binds the antigen Specificity of antigen binding determined by V H and V L

20. Antibody: Fc Fc region Constant region Base of the antibody Can bind cell receptors and complement proteins

21. Antibodies occur in 2 forms Soluble Ab: secreted in blood and tissue Membrane-bound Ab : found on surface of B-cell, also known as a B-cell receptor (BCR) Antibodies exist in two forms