Unit 3 Lecture 18 and 19 Flashcards
What are the only conditions that let T cells live?
- Positive selection to self-MHC proteins
- Negative selection to self-peptides
When a T cell can live, what happens?
It becomes immunocompetent and leaves the thymus
Define adaptive immunity
Body’s ability to recognize and defeat specific invading agents (bacteria, viruses, and foreign stuff)
What are the two ways to distinguish adaptive immunity from innate immunity?
- specificity for foreign antigens and tolerance for self proteins
- memory of past foreign antigens
What are the two types of adaptive immunity?
- Cell mediated immunity
2. Antibody mediated immunity
Cell mediated immunity involves what type of T cell
Cytotoxic T cells
Antibody mediated immunity involves what type of T cell?
Helper T cells
What must be on both T cells in order for cell and antibody mediated immunity to work?
T cell receptors
What can also be found on the surface of T cells during antibody mediated immunity?
proteins used by B cells
What protein do foreign antigens connect to during cell mediated immunity?
MHC I protein
What protein do foreign antigens connect to during antibody mediated immunity?
MHC II protein
How is cell mediated immunity specific?
defends the body against SPECIFIC pathogens that live INSIDE our cells
How is antibody mediated immunity specific?
defends the body against SPECIFIC pathogens that live OUTSIDE of cells
How are cell mediated immunity and antibody mediated immunity tolerant?
they both do NOT recognize self-antigens presented by MHC I and II but they are TOLERANT of self-proteins
What are the 2 main properties of antigens?
- Immunogenicity
2. Reactivity
Define immunogenicity
antigens stimulate proliferation of specific lymphocytes and antibodies
Define reactivity
antigens react with activated lymphocytes and antibodies developed/ released in response to them
What is a complete antigen?
An antigen that exhibits both immunogenicity and reactivity AND includes foreign proteins, nucleic acids, lipids and large polysaccharides
What are epitopes?
immune responses generated against parts of the antigens
AGAIN, what conditions allow for T cells to live?
- positive selection to self-proteins
- negative selection to self-peptides
Where do T cells go after they become immunocompetent and leave the thymus?
Go to lymphatic tissue
What conditions activate T cells to proliferate and differentiate
Antigen recognition with costimulation
What causes T cells to become inactivated or die after leaving the thymus?
antigen recognition without costimulation or deletion signal
What is the different between cell mediated and antibody mediated immunity?
cell mediated -intracellular pathogens
antibody mediated - extracellular pathogens
What are the steps for cell-mediated immune responses to occur?
- Antigen presentation
- Antigen recognition
- Activation
- Proliferation and differentiation
- Action (destruction of infected cell)
What allows cells to begin antigen presentation?
Antigen presenting cells (APCs)
What are the major APCs?
- Dendritic Cells (DCs)
- Macrophages
- Activated B cells
What is the major initiator of adaptive immunity?
Dendritic cells
What do dendritic cells do?
Travel to lymph nodes and secondary lymphatic organs where they present antigens to T cells
What additional things aids in antigen recognition during cell mediated immunity?
Cluster designation markers
- the red dangly thing coming off of helper T cells and cytotoxic t cells
What happens during antigen presentation via MHC II proteins
APCs present EXOGENOUS (outside) antigens w MHC II molecules
What happens during antigen presentation via MHC I proteins
Infected body cells present ENDOGENOUS (inside) antigens w MHC I molecules
What additional thing aids in antigen recognition during cell mediated immunity?
Cluster designation markers
- red dangly thing on help and cytotoxic T celsl
What are the 2 types of cluster designation markers?
CD4 and CD8
What cluster designation marker do helper T cells show?
CD4
What do CD4 cluster designation markers only bind to?
MHC II molecules (on all APCs)
What cluster designation marker do cytotoxic T cells show?
CD8
What do CD8 cluster designation markers only bind to?
MHC I molecules (on all nucleated cells)
During activation, what causes T cells to complete activation or abort activation?
Costimulators
What do T cells do without costimulation?
- become tolerant to antigen
- unable to divide
- do not secrete cytokines
What do T cells do with costimulation?
- enlarge, proliferate, and forms clones
- differentiate and perform functions whether helper or cytotoxic
What do cytokines do?
Costimulate T cells and T cell proliferation
What is the main type of cytokine?
Interleukin (IL-1)
What releases interleukins?
macrophages
What do interleukins (IL-1) costimulate T cells to do?
- Release interleukin 2 (IL-2)
2. Synthesize more IL-2 receptors
What is interleukin 2
- Key growth factor
- makes positive feedback cycle telling T cells to divide
- fights cancer
What are other types of cytokines?
- Perforin and lymphotoxin = cell toxins
- gamma interferon
- inflammatory factors
What do gammer interferons do?
enhances the killing power of macrophages
What do Helper T cells do when the recognize the presented antigen?
- stimulate proliferation of other T cells (important for cell & antibody mediated immunity)
- stimulate B cell to proliferate and differentiate (important for antibody mediated immunity)
