Immunology Lecture 4 PDF

Immunology Lecture 4  1. Outcomes 1. Basic anatomy of the immune system (L1) 2. Immune responses (L2‐ L6) 4. Immune‐related pathology (L7 – L8) a. Innate immunity a. Cancer a. Organs involved in immune function...

Immunology Lecture 4  1. Outcomes 1. Basic anatomy of the immune system (L1) 2. Immune responses (L2‐ L6) 4. Immune‐related pathology (L7 – L8) a. Innate immunity a. Cancer a. Organs involved in immune function i. Non‐specific immunity b. Allergy b. Cells of the immune system and their basic b. Adaptive immunity c. Hypersensitivity functions i. Cell‐mediated immunity d. Auto‐immune disorders i. Basic white blood cell functions ii. Antibody‐mediated immunity e. Transplant rejection ii. T and B cell‐specific functions f. HIV iii. Antigen presenting cells 3. External defenses (L8) 2. Adaptive immunity: Lymphocytes and antigen What is an antigen? Molecule that triggers a specific immune response. 3. Lymphocytes and receptors Binds specific Antigens: antigen T‐ independent B cells (polysaccharides) B-cell receptors T‐ dependent (proteins) Binds T cells specific antigen T-cell receptors 4. B Lymphocytes B cells Binds specific antigen B-cell receptors 1. B cells differentiate into plasma cells ‐ Produce antibodies 2. Some B cells may become memory cells  5. B Lymphocytes produce antibodies 1. B cells differentiate into plasma cells Antibody classes ‐ Produce antibodies 5 types of immunoglobulins (Ig): 2. Some B cells may become memory cells 1. IgG 2. IgA 3. IgM 4. IgE 5. IgD Fig. 12-9, p. 430  6. Antibodies Fig. 12-10, p. 431  7. Antibodies 4 interlinked polypeptide chains 2 X long: Heavy chains 2 X short: Light chains Antibody specificity Antigen‐binding fragments (Fab) Constant region (Fc) ‐ Bind mediators to elicit different responses ‐ This region is different depending on the antibody subclass Fig. 12-10, p. 431  8. Antibodies Base/ Training ground Antibodies: Defense ‐ Hinder pathogen containing the antigen Soldiers Tactics System ‐ Amplify the innate immune response Weapons * 9. Antibodies: Hinder invaders/pathogens Can also bind a few viruses and prevent them from entering host cells Fig. 12-11a, p. 432 10. Antibodies: Hinder invaders/pathogens More easily captured by phagocytes Limit functions (e.g. replication) of trapped pathogens Fig. 12-11b, p. 432 11. Antibodies & Innate responses: Complement system Fig. 12-11c, p. 432 12. Antibodies & Innate responses: Phagocytosis Antibodies as Opsonins Macrophages and Neutrophils engulf Antibody pathogen = phagocytosis Antibody Recognize foreign cells by TLRs or marked for digestion by mediators = opsonins Fig. 12-4, p. 423 13. Antibodies & Innate responses: Phagocytosis Fig. 12-11d, p. 432 14. Antibodies & Innate responses: NK cells Fig. 12-11e, p. 432 15. Antibody specificity Huge number of different foreign molecules Each B‐cell responds to only one antigen How is B cell/ antibody diversity achieved?  16. Antibody specificity: Clonal selection Diverse B cells produced during fetal development ‘100 million’ Reshuffling genetic coding sequence & mutation Fig. 12-12, p. 434  17. Antibody specificity: Primary & Secondary response Fig. 12-12, p. 434 18. Antibodies: Active vs Passive immunity Active immunity : production of antibodies through exposure Passive immunity: “borrowed immunity” Examples: ‐ IgG from mother to fetus, also IgA through breast milk ‐ Antibodies from other person/source administered clinically 19. Vaccination Louis Pasteur ‐ Anthrax vaccine ‐ Attenuated/ weakened bacteria to reduce virulence