Immunity an overview Flashcards
Define immunity, adaptive immunity and innate immunity
- immunity-the state of being immune to or protected from a organism or foreign agent
- adaptive immunity- dynamic protection results from specific immune components changing or adapting to unique features of the pathogen or foreign agent
- Innate immunity-inherent protection against organisms that are permanent from birth
WHat is passive immunity
- receiving preformed antibody
- rapid protection
- short duration T1/2 for Ab is 3 weeks
What is active immunity
exposure to a foreign antigen
slow protection
long duration-memory lymphocytes
Immunogen
a molecule that induces an immune response
antigen
a molecule that binds to (is recognized by) adaptive immunemediators
toleragen
a molecule that induces immune unresponsiveness to subsequent doses of the molecule
how does size of a substance influence its immunogenicity
large=increased immunogenecity
small=decreased immunogenecity
How does dose influence immunogenecity
Intermediate dose=large immunogenecity
high or low dose=decreased immunogenecity
How does route of administration influence immunogenecity
SubQ> Intraperitoneal > Intravenous > Intragastric
How does composition influence immunogenecity
complex= increased immunogenecity
simple=decreased
How do adjuvants influence immunogenecity
bacteria=increased
no/few bacteria=decreased
How does interaction with MHC complex influence immunogenecity
effective=increased
ineffective=decreased
Is the invadin antigen or microbe self or foreign?
self-:tolerogenic immune response against self antigens
foreign/non-self: mount an innate or adaptive immune response to the antigen or microbe
What controls specificity both for innate and adaptive immunity
- Innate: Pattern-recognition receptors-limited diversity
- TLR, Nod-like receptors
- complement proteins
- Adaptive: Antigen recptors
- T cell receptor (TCR)
- B cell receptor (BCR)
Describe the memeory for innate and adaptive immunity
innate: none
adaptive: memory B and T cells
WHat does it mean if an invading antigen or microbe is intracellular? How about extracellular?
Intracellular: located within the cells cytoplasm or within a cell vacuole
Extracellular: outside cells, either soluble or associated with the external surface of cells
Primary vs Secondary Immune Responses
- primary immune response: response to the initial exposure to the substance, slow onset
- Secodnary immune response: more rapid and stronger response to subsequent exposure to substance. fast onset after second exposure
What is a live-attenuated vaccine and what does it mostly induce?
What are pros and cons?
- micro-organism is modified to decrease pathogenecity, limited growth after injection
- mainly induces: cellular response (T cells)
- PROS: strong life-long immunity
- CONS: may revert to virulent form
What is an inactivated vaccine and what does it mostly induce?
What are pros and cons?
- pathogen is inactivated (heat or chemically) but retains an immunolgic epitope on surface
- mainly induces: Humoral Response (B cells)
- PROS: stable and safer than Live
- CONS: Weaker immunity, requires boster
WHat 3 things help the body make immunologic decisions?
cells, soluble mediators, surface receptors
What are generative immune organs?
What are peripheral immune .organs?
- Generative immune organs:
- bone marrow
- thymus
- Peripheral immune organs:
- lymph nodes
- spleen
What is innate immunity
- Always present
- Respons immediately
- comprised of
- epithelial barriers
- phagocytic leukocytes (macrophage, neutrophil)
- Natural killer cells
- Plasma proteins such as complement
What is adaptive immunity
- normally silent-activated to adapt and neutralixe pathogens (antigen specific)
- respond slowly to first exposure
- memory: faster response to subsequent exposure
- comprised of: T cells (cell-mediated immunity) and B cells (humoral immunity)
Describe the function, characteristics and mechanism or innate immunity
- Function: provide primary defense against invading pathogens
- characteristics: immediate response always ON and doesn’t require previous exposure for activation
- Mechanism:
- natural barriers (epithelium-skin, mucous membranes)
- phagocytic cells-macrophages, neutrophils
- Dendritic cells
- Natural killer cells
- Alternative lectin complement pathway
How is the innate immune system activated?
- Patter Recognition Receptors (PAMP) on bacteria, virus, fungal or parasite pahtogens. e.g.: TLRs
- this actiavtes a defined series of proinflammatory or antiviral signaling
- there is NO MEMORY so the response will be immediate and the same to the subsequent infection.
Describe the function, characteristics, and mechanism of adaptive immunity
- Function: provide antigen specific defence
- Characteristics
- must be activated by invading antigen
- cascade of events
- prepare for future defense=immune memory
- mechanism: T cell and B cell
How is the adaptive immune system activated?
- antigen-a molecule that binds to an Antibody or T cell receptor
- epitopeL the specific portion of the macromolecular antigen recognized by receptors expressed on lymphocytes
- Antibody (B Cell receptor): recognize eptiopes on macromolecular proteins and lipids
- T Cell Receptor: recognize epitopes on peptide fragments complexed with either an MHC class I or MHC class II presentation molecule
Describe the T Cell Response
- T=thymus
- function: antigen specific immune response to Intracellular pathogens
- Types activated by different antigen presentation styles
- cytotoxic=CD8: MHC class I restrcited and the goal is to KILL!
- Helper=CD4: MHC class II restrcited and the goal is to recruit/activate
- cytokine secretion
- CD40:CD40L
Describe the B cell response
- B=Bone Marrow
- funciton is antigen specific immune response to extracellular pathogens/antigens and immune surveilance
- types=plasma cells
- secrete soluble antibodies and have isotypes (IgM, IgG, IgA, IgE)
List the cells of the innate immune system
- phagycytes
- neutophils
- macrophages
- Granulocytes
- eosinophils
- basophils
- mast cells
WHat cell link the innate and adaptive immune systems?
dendritic and natural killer cells (NK)
What are the cells of the adaptive immune system
lymphocytes
CD4 T cells
- function
- key markers
function: B cell differentiation, macrophage activation
key markers: CD3, CD4
CD8 T cells
functions
key markers
function: Kill microbe infected cells, tumor cells
Key markers: CD3, CD8
Regulatory T cells
function
key markers
- function: supress T cell function
- key markers: CD3, CD4, CD25
B Cells
function
key markers
function: Produce Ab
key markers: FcR, CD19, CD21
NK Cells
function
key markers
function: Kill virus-infected cells, damaged cells, tumors
key markers: CD16, FcRy
What are the primary (generative) lymphoid tissues and describe them? Do th same for secondary, what are they?
- Primary:
-
bone marrow: hematopoietic progenitors, lymphocyte development
- naive lymphocytes (small)
- mature lymphocyte( larger0
- thymus: development and maturation of T lymphocytes
- Secondary
- lymph nodes
- spleen
- Mucosal or skin associated lymphatic tissue (MALT/SALT)
- peyers patches, tonsils
