Ch 15: The Immune System

SLOs List 6 types of leukocytes and explain their functions in the IS Compare and contrast innate (nonspecific) and acquired (specific) immunity Compare and contrast humoral immunity and cell-mediated immunity Compare and contrast 1° and 2° responses Describe self-tolerance and the consequence of its breakdown

3 Major Functions Protection from disease causing invaders (such as ?) Removal of dead /damaged tissues & cells Recognition & removal of abnormal cells

The Concept of Immunity Immunity: Ability to ______________________. Susceptibility: Lack of ________________to a disease. specific

Activation of Innate Immunity 1st line of Defense: Physical & chemical barriers keep pathogens out. E.g.: ___________________________ Example of 2nd line of Defense: Host cells have Toll-like receptors (TLRs) they attach to Pathogen-associated molecular patterns (PAMPs) Binding to TLRs induces release of cytokines  regulate intensity and duration of immune responses

TLRs = ? PAMPs recognition

Immune Cells      6 types of blood and tissue cells involved in IS: 1) 2) 3) 4) 5) 6) Which ones are APCs? Which ones are phagocytes?

Antigen Presenting Cells 3 types of APCs: __________ _________ _________ Also stationary Ms: In lung: In liver: In bone: In brain: etc.

Phagocytosis Patrolling and stationary WBCs attack and destroy pathogens/foreign molecules nonspecifically Fig 15-1

Adaptive (Specific) Immunity Antigen (pathogen) specific Overlaps with innate immunity 1o cell type involved? __________________ two subgroups: 1) ___________ 2) ___________ Is systemic (= whole body involved) Has ___________ Uses cytokines (e.g. interleukins & interferons) for communication

2 Branches of Acquired Immune System: Humoral or ___________ mediated Cellular or ______ mediated

Humoral Immunity Memory cells Effector cells Virgin (naïve) B Lymphocyte Compare to Fig 15-7 Memory cells Effector cells

Antibodies = Immunoglobulins Fig 15-8 Heterogenous group of molecules: 5 subclasses

Fig 15-9

5 subclasses of Igs: Ig G: main ab in serum; + main ab during 2o response Ig A: main ab is external secretions Ig E: main ab in allergic reactions Ig M: ab on virgin B-cells; + main ab during 1o response Ig D: ab on virgin B-cells

2 immune response: stronger & more rapid Mostly Ig Ms 2 immune response: stronger & more rapid Importance of Immunizations!! due to?? < 2 h Ig Gs Fig 15-20

Antibody functions by “working against foreign body”

B lymphocytes ________ cellular immunity humoral vs. review T lymphocytes cytotoxic (killer) helper memory review

T-Cell Development TCR cannot bind free ag! Ag must be presented by APC in connection with MHC molecule TCRs can only bind to MHC-ag complex Tc activated by Th activated by

Importance of MHC molecules High # of MHC alleles in population (Transplant rejection in case of incompatible MHC) MHC class I: found on surface of all nucleated cells – used to present peptides from intracellular invaders or cancer cells T-cytotoxic cell recognizes MHC I MHC class II: found on surface of APCs T-helper cell recognizes MHC II

TC Action: one of 2 Mechanisms 1) Perforin molecules create protein channels in target cell membrane Granzymes enter and trigger apoptosis in target cell Youtube

Viral Infections require Tc-cells Initial response similar to bacterial infection, then Intracellular defense mechanisms needed once virus enters host cell. Tc → reacts to viral ag presented by MHC __ complex Activated M release - interferons. These induce ________________________

Active vs. Passive Immunity Active: Exposure to ___________ Passive: Transfer of antibodies or immune cells into non-immune host

Allergy Inflammatory immune responses to non-pathogenic antigens Symptoms range from mild tissue damage to fatal Immediate Hypersensitivity: e.g.: ___________ _______________ ab mediated (Ig___) Delayed Hypersensitivity: e.g.: _______________ due to T-cell abnormality

Sensitization phase = 1o immune response. What is an allergen? Strong genetic predisposition Sensitization phase = 1o immune response. Reexposure: 2o immune response Anaphylaxis  Hives, bronchoconstriction and widespread vasodilation  ? Fig. 15.23 Immediate Type HS

Poison Oak Delayed Type HS Tc cells (attracted by lymphokines) release lytic enzymes and perforins  destroy allergen and skin cells.

Immune Response Pathways: 4) Organ & Tissue Transplants MHC (= HLA) are the 1º tissue antigens Establishment of “self tolerance” during T cell development ABO (and Rh) blood typing (AA, AO, BB, BO, AB, OO) Blood transfusion problems due to antibodies in plasma  Transfusion reaction with hemolysis and possible kidney damage

Recognition of Self the end Important function of IS: Self-tolerance through clonal ______________ Failure of self tolerance: _______________ the end