Porth Chapter 13 Flashcards
Immune Response
The collective, coordinated response of the cells and molecules of the immune system
Innate or nonspecific immunity
the natural resistance with which a person is born
Adaptive or specific immunity
the second line of defense, responding less rapidly than innate immunity but more effectively
Lymphocytes
Cells that specifically recognize and respond to foreign antigens
Accessory cells
Macrophages and dendritic cells
Function as antigen-presenting cells by the processing of a complex antigen into epitopes required for the activation of lymphocytes
Cytokines
soluble proteins secreted by cells of both the innate and adaptive immunity
Chemokines
cytokines that stimulate the migration and activation of immune and inflammatory cells
Colony-stimulating factors
stimulate the growth and differentiation of bone marrow progenitors of immune cells
Innate Immunity
Components
Epithelial barriers
Phagocytic cells
Neutrophils and macrophages
NK cells
Plasma proteins
Opsonins, cytokines, and acute-phase proteins
Induction of inflammatory response
Soluble Mediators of Innate Immunity
Opsonins—facilitation of phagocytosis
Acute-phase reactants, lectins, complement proteins
IgG and IgM with adaptive immunity
Cytokines—TNF, interleukins, interferons, and chemokines
Acute-phase proteins
Mannose-binding ligand and C-reactive protein
Complement system
Cytolysis, opsonization, chemotaxis, anaphylaxis
Innate Recognition Systems
Pattern recognition receptors (PRRs)
Pathogen-associated molecular patterns (PAMPs)
Toll-like receptors (TLRs)
The Complement System
The complement system is found in the blood and is essential for the activity of antibodies.
Activation of the complement system increases bacterial aggregation, which renders them more susceptible to phagocytosis.
Adaptive Immunity
Able to recognize and react to a large number of microbes and nonmicrobial substances
Ability to distinguish among different, even closely related, microbes and molecules and to “remember” the pathogen by quickly producing a heightened immune response on subsequent encounters
Lymphocytes and their products
Antigen identification
Humoral Immunity
Mediated by molecules in the blood
The principal defense against extracellular microbes and toxins
Cell-Mediated Immunity or Cellular Immunity
Mediated by specific T lymphocytes
Defends against intracellular microbes such as viruses
Regulatory Cells
Assist in orchestrating and controlling the immune response
Effector Cells
Accomplish the final stages of the immune response with the elimination of the antigen
Activated T lymphocytes, mononuclear phagocytes, and other leukocytes function as effector cells in different immune responses.
Antigens
substances foreign to the host that can stimulate an immune response.
Antibodies
recognize antigens
Receptors on immune cells
Secreted proteins
Types of Antigens
Bacteria
Fungi
Viruses
Protozoa
Parasites
Nonmicrobial agents
Properties of MHC Molecules
HLA Antigens
Class I: HLA-A, HLA-B, HLA-C
Class II: HLA-DR, HLA-DP, HLA-DQ
Distribution
Class I: virtually all nucleated cells
Class II: restricted to immune cells, antigen-presenting cells, B cells, and macrophages
Functions
Class I: present processed antigen to cytotoxic CD8+ T cells; restrict cytolysis to virus-infected cells, tumor cells, transplanted cells
Class II: present processed antigenic fragments to CD4+ T Cells; necessary for effective interaction among immune cells
Antigen Presentation
Macrophages and dendritic cells process and present antigen peptides to CD4+ helper T cells.
Capture antigens and then enable their recognition by T cells
Initiation of adaptive immunity
B cells
Humoral immunity
Memory
T cells
Cell-mediated immunity
Memory
Identifying Factors of B Lymphocytes
Presence of membrane immunoglobulin that functions as the antigen receptor
Class II MHC proteins
Complement receptors
Specific CD molecules
Functions of T Lymphocytes
The activation of other T cells and B cells
The control of intracellular viral infections
The rejection of foreign tissue grafts
Delayed hypersensitivity reactions
IgG
displays antiviral, antitoxin, and antibacterial properties, responsible for protection of newborn; activates complement, and binds to macrophages
IgA
predominant Ig in body secretions; protects mucous membranes
IgM
forms natural antibodies; prominent in early immune responses, activates complement
IgD
found on B lymphocytes, needed for maturation of B cells
IgE
binds to mast cells and basophils; involved in parasitic infections, allergic and hypersensitivity reactions
Central lymphoid organs (bone marrow and the thymus)
Provide the environment for immune cell production and maturation
Peripheral lymphoid organs
Function to trap and process antigen and promote its interaction with mature immune cells
Functional Groups of Cytokines
One group of cytokines (e.g., IL-1, IL-6, TNF) mediates inflammation by producing fever and the acute-phase response and by attracting and activating phagocytes (e.g., IL-8, IFN-γ).
Other cytokines are maturation factors for the hematopoiesis of white or red blood cells (e.g., IL-3, granulocyte–macrophage colony-stimulating factor [GM-CSF]).
Active Immunity
Specific protection induced following exposure to antigens
Passive Immunity
Specific protection induced through transfer of protective antibodies against an antigen
Transferred from another source
Maternal IgG crosses the placenta and protects the newborn during the first few months of life.
IgA in colostrum
Development of an Immune Response
Fetal development at 5 to 6 weeks
Secondary lymphoid organs well developed at birth
IgA and IgM shortly after birth
Reach adult levels by 1 year of age
The Elderly Immune System
Declining ability to adapt to environmental stresses
Decline in immune responsiveness
Decrease in the size of the thymus gland
Biological clock in T cells
Altered responses of the immune cells to antigen stimulation
