EXAM 4: Adaptive Flashcards
Antigen
A foreign substance that induces an immune response in the body
Epitope
The part of an antigen that is recognized by a specific antibody
Lymph
A fluid derived from the tissues of the body, resembling blood plasma (contains WBCs) and conveyed to the bloodstream by the lymphatic vessels
Cluster of Differentiation
A protocol used for the identification and investigation of cell surface molecules providing targets for immunophenotyping of cells
Leukocytes
cells of the immune system involved in defending the body against infectious disease
Lymphocytes
A cell of the adaptive immune system
Cytokine
Signaling molecules secreted by certain cells of the immune system and have a direct effect on other cells
Chemokines
Ability to induce directed chemotaxis in nearby responsive cells
Clonal Expansion
An immunological response in which lymphocytes stimulated by an antigen proliferate and amplify the population of relevant cells
Cytotoxic
Toxic to living cells
Opsonization
The process by which a pathogen is marked for ingestion and destruction by a phagocyte
Agglutination
A reaction in which particles suspended in a liquid collect into clumps
List and describe the attributes of the adaptive immune response.
Unlike innate immunity, adaptive immunity has resistance to a particular foreign agent (memory), resistance increases with repeated exposure
Traits are: AIDS
- antigenic specificity: has specific responses for specific antigens
- immunological memory: defense gets stronger upon repeated exposure
- diversity: can remember & defend against a wide range of pathogens
- self-nonself recognition: able to differentiate between normal cells/products in body and those of antigens
Define antigen and discuss the role of antigens in the immune response
Def: A foreign substance that induces an immune response in the body
- the body recognizes certain molecules worthy of attack
- causes immune system to produce antibodies against it
- Recognized by 3D regions called epitopes
- Include various bacterial components
- Food and dust can also contain antigenic particles
Autoantigens: regular cell presentation on cell membrane
Exogenous antigens: presented on surface of bacterial cell
Endogenous antigens: presented on surface of virally infected host cell
List the elements of the of the adaptive immune response, including cells, organs, tissues, signaling molecules and describe their specific roles
Lymphatic system: screens the tissues of the body for foreign antigens
* transitions from innate to adaptive response
ANTIGEN PRESENTATION OCCURS HERE
Lymph:
A fluid derived from the tissues of the body, resembling blood plasma and containing white blood cells, and conveyed to the bloodstream by the lymphatic vessels
* Flow of lymph: a one-way system that conducts lymph from tissues and returns it to the circulatory system
Lymphoid Organs:
Primary: red bone marrow, thymus (mature)
Secondary: lymph nodes, spleen, tonsils, MALT (mucosa associated lymphatic tissue)
Lymphocytes:
Identified by cluster of differentiation (CD)
3 major populations:
1. T lymphocytes:
* arise in bone marrow, mature in thymus
* mature cells are naïve until activated during antigen presentation
* Proliferate into various effector and memory cells
CD8+ cytotoxic T lymphocyte: directly kills virally infected cells and abnormal cells
CD4+ helper T lymphocyte: helps regulate B and T cell activities
-
B cells:
* arise and mature in RB marrow
* Job is differentiation into the plasma cells and secretion of antibodies -
natural killer cells:
* cytotoxic activity by secreting toxins onto surface of virally infected cells and tumors
* recognizes low levels of MHC1 & Fc portion of antibodies
* non-specific
T Cell Receptor
* On T cell cytoplasmic membrane
* Do not recognize epitopes directly- only through association with an MHC protein
* intracellular pathogens
B cell Receptor
* Each B cell generates a single BCR (mult. receptor copies)
* Recognizes only one epitope
* Two variable regions of the BCR form the AntBinding sites
* The entire collection of an individual’s BCRs can recognize millions of different epitopes
Discuss antibody structure, including different types, and function
Antibody Structure:
* Composed of Fc Body, 2 heavy chains and 2 light chains (linked by disulfide bonds & chains have constant and variable regions)
* Fc body determines type & function of antibody
* antibodies are immunoglobulins similar to BCRs
* secreted by plasma cells
* Antigen-binding sites are complementary to epitopes
ANTIBODY KILLING:
activation of complement
neutralization
opsonization
oxidation
agglutination
antibody-dependent cellular toxicity ADCC
Classes of Antibodies:
* Since threats to immune system vary, so do antibody capabilities
* Class involved in the immune response depend on antigen type, portal of entry & antibody function needed
5 Classes:
IgM: 1st antibody secreted, pentamer, neutralization/agglutination, can activate complement, can pass placenta
IgA: associated w/ body secretions, dimer, neutralization/agglutination
IgG: most versatile, highest concen. & longest lasting antibody, can activate complement
IgE: allergies, response to parasitic infections
IgD: function unknown
Compare and contrast the two classes of MHC molecules
Major Histocompatibility Complex: antigens bind in groove of MHC molecules, hold and position antigenic determinants for presentation to T cells
MHC class I:
* found on all nucleated cells
* self and nonself recognizing
* cells display antigens to CD8+ cytotoxic T lymphocytes
* on surface of nuc. cells
* presents endogenous antigen
MHC class II:
* found on all APCs and B-cells
* non-self recognizing
* works with foreign antigens
* cells display antigens to CD4+ helper T cells
* on surface of activated APCs, requires AP
* presents exogenous antigen
Compare and contrast clonal selection and clonal deletion
Clonal deletion: it is vital that immune responses not be directed against autoantigens; body eliminates self-reactive lymphocytes through apoptosis
Clonal selection: antigen presentation by dendritic cells lead to activation of T cells, which causes rapid expansion of Active T cells (some memory T cells created)
Describe the process by which different cells of the immune system communicate with each other.
List the receptors and signaling molecules used
Cytokines: Signaling molecules secreted by certain cells of the immune system and have a direct effect on other cells. SOLUBLE REG PROTEINS that act as intercellular signals
* Secreted by various leukocytes
* Cytokine network: complex web of signals among all the cells of the immune system
Cytokines examples:
* interleukins: signal among leukocytes
* chemokines: Ability to induce directed CHEMOTAXIS in nearby responsive cells. CHEMOTACTIC cytokines that signal LEUKOCYTES to move
Receptors used:
- BCRs, TCRs, antigens, etc.
Describe the main events in cellular and humoral immune responses
cellular:
* Cell-mediated immunity
* T cells require additional signaling from antigen presenting cells (prompts T cell to respond to the antigen)
4 STEPS to activate T Cell clones:
Antigen presentation
Helper T cell differentiation
Clonal expansion
Self-stimulation
humoral:
* Antibody-mediated immunity
B cells must be activated and differentiated into plasma cells
* Secrete antibody molecules complementary to specific antigen
* Short lived cells
T Independent B cell activation
BCR binds antigen directly, clonal expansion/differentiation
T Dependent B cell activation
BCR binds with antigen on a corresponding TCR
Discuss the role of memory cells in the immune response, including the primary and secondary immune response
memory B-cells:
* persist for months or years in the lymphoid tissue
* do not secrete antibodies
* have BCRs complementary to the antigenic determinant that triggered their production
* initiate antibody production if antigen is encountered again
memory T-cells:
* persist for months or years in lymphoid tissues
* some activated T cells become memory T cells
* immediately functional upon subsequent contacts with epitope specific to its TCR
When B and T-cells replicate during the primary immune response, they produce effector cells and long-lived memory cells.
Since both are antigen-specific, when they encounter the antigen again, they can mount a more rapid/effective immune response, this is the secondary immune response
Compare and contrast the two types of acquired immunity. Differentiate between active and passive
Acquired immunity: specific immunity acquired during life
naturally: response against antigens encountered in daily life/nature
artificially: response to antigens introduced from a vaccine
draw out chart!
active: immunity developed after exposure to infection/vaccine
natural: Abodies made after exposure to infection
artificial: Abodies made after getting a vaccine
passive: immunity acquired from someone else
natural: Abodies transmitted from mother to baby (milk/placenta)
artificial: Abodies acquired from immune serum medicine
Discuss the how the innate and adaptive immune responses work together to fight off infection.
innate acts at first fighting off new pathogens with it’s granulocytes, physical barriers, and chemical barriers.
from the innate immune system dendritic cells pass on the antigen information to the adaptive immune system so that the body is able to prevent infection and illness if the pathogen appears again
