acquired immunity: humoral & cell-med. distinction of humoral versus cell-mediated acquired...
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Acquired Immunity: Humoral & Cell-Med.• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time, Vaccines
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated (Adaptive) Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Secondary Response (Immunity)
Figure 12.13
Types of Vaccines Live, attenuated vaccines: passed through unnatural host or a
related non-virulent virus
• Benefits: Strong immune response, provide extended response
• Potential Problems: Underattenuation, mutation back to virulent form
Inactivated/dead “whole” microbial vaccines
• Benefits: Moderately immune response, less chance of causing disease
• Potential problems: incomplete inactivation
Subunit vaccines: pieces of outer layer of microbes, often produced through biotechnology
• Benefits: No chance of causing disease, safer
• Problems: Weaker immune response
Subunit Vaccines Made of Microbial Parts
Vaccine Production: Coinfecting With Two Strains
Acquired Immunity: Humoral Response• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Results of Antibody Binding to Antigen• Agglutination (coralling of the invader)
• Precipitation (removal of soluble antigens from blood and lymph)
• Neutralization (blocking antigen's activity and binding)
• Opsonization (faciliating macrophage phagocytosis)
• Tagging, complement fixation, and transmembrane channel formation (lysis of pathogen)
Agglutination Precipitation (soluble antigens)
Transmembrane channel
formation and lysis
Antibody Function movie
Active vs Passive Immunity Active Immunity
• Your B cells encounter antigens and produce antibodies
• Active immunity can be naturally or artificially acquired (e.g via vaccination)
Passive Immunity
• Antibodies are obtained from someone else
o Conferred naturally from a mother to her fetus
o Conferred artificially from immune serum or gamma globulin - e.g. snake antitoxin
• Immunological memory does not occur
• Protection provided by “borrowed antibodies”
Monoclonal Antibodies Antibodies prepared for clinical
testing or diagnostic services
Produced from descendents of a single cell line
Examples of uses for monoclonal antibodies
• Diagnosis of pregnancy
• Treatment after exposure to hepatitis and rabies
• HIV/AIDS detection in ELISA Assays
• Identifying microbes by using fluorescent-tagged antibodies against known organisms
Monoclonal Antibodies Can Be Used To Deliver Cell Poisons
E.g. Rutuxin-mab for non-Hodgkin’s lymphoma tags B cells, causing apoptosis, NK cell, or complement lysis
Acquired Immunity: Humoral Response• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Cellular (Cell-Mediated) Immune Response
1. Antigens must be presented by macrophages, dendritic cells, or B cells to a T helper (TH) cell (called “antigen presentation”)
2. T cells must recognize non-self antigen and self MHC proteins (double recognition)
3. After antigen binding, clones form as with B cells, but different classes of cells are produced
Cell-Mediated (Adaptive) Response
Types of T Cells Cytotoxic T (Tc) cells - CD8+
• Specialize in killing infected cells
• Insert a toxic chemical (perforin)
Helper T (TH) cells - CD4+ Recruit other cells to fight the invaders
• Interact directly with B cells
A few members of each clone are memory cells
Helper t cells animation
Cytotoxic t cells animation
Recognition Proteins Found on T cellsCD8: special membrane glycoprotein found
on cytotoxic T (TC) cells only
• CD8 glycoprotein, therefore T cells designated as CD8+
• Function
o Bind to class I MHC molecules on almost every body cell to identify “self” from “non-self” but to kill “bad” self-cells
CD4: different membrane glycoprotein found on TH, monocytes, macrophages, dendritic cells
• CD4 glycoprotein, therefore Tcells designated as CD4+
• Function
o Bind to and recognize class II MHC molecules on dendritic cells, macrophages, or B cells to verify they have a security force name tag”.
Summary of B Cell Activation
B cells can be activated directly by antigen or from a TH cell activated by an antigen-presenting macrophage
Summary of the Immune Response
Acquired Immunity: Humoral Response• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Organ Transplants and Rejection Major types of grafts
• Autografts – tissue transplanted from one site to another on the same person
Hey buddy, my patch of skin is damaged! Can I have your autograft?
• Isografts – tissue grafts from an identical person (identical twin)
• Allografts – tissue taken from an unrelated person (sometimes successful)
• Xenografts – tissue taken from a different animal species (rarely successful)
Allergies (Hypersensitivity) Abnormal, vigorous immune responses
Type I -IgE antibodies bind to mast cells
• Immediate hypersensitivity
o B cells exposed to foreign antigen and IgE antibodies are made
o Reaction triggered by release of histamine from IgE binding to mast cells
o Reactions begin within seconds of contact with allergen
o Anaphylactic shock – dangerous, systemic response
• Delayed hypersensitivity
o Triggered by the release of lymphokines from activated helper T cells
o Symptoms usually appear 1–3 days after contact with antigen
o E.g. reaction to poison ivy, contact dermatitis
Type II - complement lyses antibody-tagged cells
• Immediate reactions, life threatening
o E.g. Transfusions, hemolytic disease of newborns
Acquired Immunity: Humoral Response• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Disorders of Immunity: Immunodeficiencies Autoimmune Diseases (antibodies attack own tissues)
• Multiple sclerosis – Schwann cells and oligodendrocytes forming myelin sheaths are destroyed, slowing communication, esp. muscles
• Myasthenia gravis – antibodies blocking acetylcholine receptors on post-synaptic side of neuromuscular junction; muscle weakness
• Juvenile diabetes – destroys pancreatic beta cells that produce insulin
• Rheumatoid arthritis – destroys joints by attacking tissues and causing inflammation
• Systemic lupus erythematosus (SLE) – affects kidney, heart, lung and skin
• Glomerulonephritis – impairment of renal function
• Grave’s disease - antibodies bind to TSH receptors on thyroid follicular cells, stimulating overproduction of thyroxine
Inefficient lymphocyte programming (e.g. T cells that escaped "education")
Appearance of self-proteins in the circulation that have not been exposed to the immune system (eggs, sperm, eye lens)
Cross-reaction of antibodies produced against foreign antigens with self-antigens
• Rheumatic fever - Anti-streptococcal antibodies also attack myocardium and joints; --> arthritis, congestive heart failure
Acquired Immune Deficiency Syndrome (AIDS)
HIV and Acquired Immunodeficiency Syndrome
Titers of TH cells and blood viruses
Diseases of AIDSLife Cycle of Human Immunodeficiency Virus
Acquired Immunity: Humoral Response• Distinction of Humoral versus Cell-Mediated Acquired Immunity
• Antigens and Antigenic Determinants: Non-self and MHC proteins
• Cell Types of the Humoral Response and How they Develop
• B and T cell receptors and immunglobulins (antibodies)
• Antibody Structure and Classes
• Activation of B cells and Clonal Selection
• Immunity and Secondary Response Time
• Antibody Actions
• Passive and Active Immunity
• Monoclonal Antibodies
• Players in the Cell Mediated Response
• Activation of Cytotoxic T and B cells via TH cells
• Other T cells and their function
• Tissue grafting
• Immune disorders: Allergies
• Immune disorders: Immunodeficiency
Activation of T and B Cells Through TH cells
MHC "self"
identifying
protein