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Adaptive Immunity: specific host defenses
Terms in this set (44)
3rd line of defense
Which line of defense does adaptive immunity fall into?
Specific antibody and lymphocyte response to an antigen
Proteins made in response to an antigen; can combine with that antigen.
Serum proteins that bind to antibodies in an Ag-Ab reaction; cause cell lysis
Involves antibodies produced by B cells (lymphocytes)
Involves T cells (lymphocytes)
Through receptors on their surfaces
How do T cells recognize their antigens?
T cells= thymus
B cells= Red bone marrow
Where do T and B cells come from?
Antibodies recognize and react with _______________ or epitopes on an antigen.
Recombination events in the portion of the antibody gene that codes for the variable (V) portion
How are a huge amount (10^15) of antibodies able to be made from just hundreds of genes?
4. Antibody-dependent cell-mediated cytotoxicity
5. Activation of complement
What are the 5 consequences of Ag-Ab binding?
Body usually doesn't make antibodies against itself
Through clonal selection: the process of destroying B and T cells that react to cell antigens
How is self-tolerance achieved?
Crohn's disease/ulcerative colitis
Examples of diseases resulting from self-attack?
Either T cell independent (humoral response) or T cell dependent (cell mediated response)
How are B cells activated?
Antigens with repeating epitopes are strong enough to activate B cells independently of T cells. An example of these types of antigens are bacterial capsules.
How does T cell independent activation work?
1. Stem cells differentiate into mature B cells, with a surface immunoglobulin against a specific antigen
2. Binds with specific antigen and proliferates
3 & 4. Memory cells or antibody-producing plasma cells
5. Plasma cells secrete antibodies into circulation
How are B cells differentiated?
Help fight in an infection and are activated by antigen presenting cells (APCs) such as macrophages
Helper T cell (TH1)
Activate B cells to make antibodies
Helper T cell (TH2)
Stimulate other immune cells to attack pathogens
Helper T cells
What do CD4 cells mature into?
Cytotoxic T cells
Induce infected cells to kill themselves (apoptosis); destroys target cells on contact
T Regulatory cells
Regulates immune response and helps maintain tolerance
enhanced phagocytic activity; attacks cancer cells
Natural Killer cell
Attacks and destroys target cells; participates in antibody-dependent cell-mediated cytotoxicity
Cytotoxic T cells
What do CD8 cells mature into?
1. Immunoglobulin receptors on B cell recognizes and attaches to antigen
2. Antigen-fragment complex is displayed on B cell surface
3. T helper cell recognizes complex and is activated, cytokines produced which activates B cells
4. B cell begins clonal expansion and some become antibody-producing plasma cells
How does T Cell dependent activation of B cells work?
Neutrophils=fungi and extracellular bacteria
Mast cell, Basophils, Eosinophils= helminths
macrophages= intracellular bacteria and Protozoa
T Helper cells activate WBCs which target certain pathogens examples
CD8 T cells recognize host cells presenting "non-self" antigens. Once they bind to the antigen, they become cytotoxic and kill the abnormal/infected cell
How do Cytotoxic T cells kill infected cells?
Antigen-Presenting cells (APCs)
Digest antigen and present Ag fragments on cell surface
Dendritic cells and macrophages
What are the two types of APCs?
-present in lymph nodes and skin
-good antigen presenters
-usually found in "resting" state
-very phagocytic once activated
-activated by ingestion of antigen or by T helper cells
1. APC encounters and ingests a microorganism, processes it, and presents it on its surface
2. CD4 T helper cell binds to antigen complex, stimulated, and signals activate the T helper cell, which produces cytokines
3. Cytokines cause T helper cells to become activated
How do APCs activate T helper cells?
some microbes are larger than the immune cells so they cannot be digested (parasites/flukes); macrophages and eosinophils release cytokines, lytic enzymes and perforin enzymes to attack microbes that cannot be ingested
Occurs after initial contact with the antigen
Secondary (memory) response
after subsequent exposure (stronger and more specific)
Vaccination is an attempt to push you to a second response BEFORE encountering the infectious agent or toxin
How do vaccines work in relation to immunological response/memory?
Naturally acquired and artificially acquired, which can both be separated into active and passive
First ask how it was acquired (naturally or artificially) and then ask if you make your own antibodies (active) or if antibodies were previously made and then given to you (passive)
What are the types of adaptive immunity? And how can you differentiate between them?
Naturally acquired active immunity
antigens enter the body naturally; body induces antibodies and specialized lymphocytes
ex: getting sick with a cold
Naturally acquired passive immunity
antibodies are passed from mother to fetus via the placenta and breast milk
Artificially acquired active immunity
antigens are introduced in vaccines; body produces antibodies and specialized lymphocytes
Artificially acquired passive immunity
preformed antibodies in immune serum are introduced by injection
The virus attaches to a receptor and co-receptor on the cell via spikes, fuses with the cell, creates an entry pore, HIV uncoats, and releases RNA core to replicate. Can either be a latent or active infection. Then it attacks the T helper cells which significantly compromises the immune system since this cell initiates many processes. You usually do not die from HIV/AIDS, you die from a secondary infection due to a compromised immune system.
How does HIV/AIDS affect the immune system?
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