Antigens and Adaptive Immunity Flashcards
Adaptive Immune Response:
- Interacts with ____ via ___
- ____ specific
- ____ onset
- has ____
innate immunity; antigen presenting cells; antigen; delayed; memory
adaptive immune response has 2 pathways:
- cell-mediated
- humoral
cell-mediated response effector cells
cytotoxic T cells/CD8+
cytotoxic T cells/CD8+ have ____ receptors and they target ____
specific cell-surface;
virally infected cells, cancerous and precancerous cells
humoral response effector cells
B cells
B cells have ____ receptors; they differentiate into ___ which ____
specific cell-surface;
plasma cells;
secrete antibodies
antibody characteristics
- specific to antigen
- circulate in the blood
- “fluid immunity”
antibodies target ____
bacteria; toxins in solution
cell-mediated response and humoral response are both _____
activated by helper T cells
antigens are molecules that ____
elicit an immune response
key antigen characteristics
- degree of foreignness to host
- size (ex: hapten)
- chemical complexity
- amount
antigens recognized as “non-self”
- pathogens
- tissue
- blood products
- bee venom
- pollen
- foods
APCs are necessary for ____
activation of adaptive immune system
APCs process and present ____
antigens on MHC molecules
two classes of APCs
professional and non-professional
two most important professional APCs
macrophages and dendritic cells
dendritic cells are resident cells of ____ tissues
epithelial
dendritic cells migrate to ____, where they ____
secondary lymphoid tissues;
present to naive cells in lymph nodes
MHC molecules are ____ on surface of all cells; they are responsible for ____
glycoproteins;
self/non-self determination
MHC also called ____ in humans; they code for ____ and are located on ____
human leukocyte antigen gene complex (HLA);
MHC proteins;
the short arm of chromosome 6
MHC molecules are important for ____; want to match them to ____
organ donation;
avoid rejection
three classes of MHC molecules
I, II, III
MHC I proteins:
- found on ____
- ____ APCs
- presents to ____
- presents ____; normal: ____, damaged or foreign: ____
all nucleated cells; non-professional and professional; circulating cytotoxic T cells (CD8+); endogenous antigens; no response; initiate response
MHC II proteins:
- found on ____
- presents ____ after ____
- presents to ____, which ____
professional APCs only (dendritic cells, macrophages, B-cells); exogenous antigens; phagocytosis and processing; specific helper T-cells (CD4); initiates adaptive immune response
epitope
portion of antigen that is the “tag”; segment of the antigen that our immune system recognizes
paratope
variable portion on the T- or B-cell or antibody binding site; part of our immune system that recognizes the epitope
antigen receptors
- T-cell receptors
- B-cell receptors
- circulating antibody (immunoglobulin)
antigen-receptor binding characteristics
- noncovalent
- affinity
- valence
- avidity
adaptive immune response development and activation
1) generation of specific antigen receptors
2) antigen recognition and processing
3) activation and production of immune cells specific for the antigen
4) production of memory cells
clonal diversity:
- occurs ____ in the ____
- receptor specificities created by _____
- results in _____
- each T- and B-cell produced has ____
- T- and B-cells migrate to ____
before (and after) birth;
primary (central) lymphoid organs (thymus and bone marrow);
somatic recombination;
naive but immunocompetent T- and B-cells;
a unique receptor;
secondary lymphoid tissues
clonal deletion:
- occurs ____
- ____ are destroyed during fetal development
- generates ____
at the end of the Clonal Diversity process;
“self-reactive” B- and T-cells;
“central tolerance”
clonal selection:
- APCs present antigens to ____
- T-cells: activated by ___
- B-cells: can also be activated by ____
- activated cells ____
naive lymphocytes in secondary lymphoid tissue;
MHC-II bound antigen on APC;
bacteria that enters lymph nodes;
proliferate, producing multiple clones with receptors specific for the activating antigen
CD4+ Helper T-cells become activated when they ____
bind a matching antigen presented by an APC-MHC II complex
helper T-cells “help” cytotoxic T-cells ____
target cancer and virally infected cells
helper T-cells “help” B-cells ____
become plasma cells
helper T-cells initiate maturation of B- and T-cells; steps: ____
1) activation
2) differentiation/replication
3) facilitation
helper T-cells initiate maturation of B- and T-cells:
activation
recognize specific antigen via MHC II presentation
helper T-cells initiate maturation of B- and T-cells:
differentiation/replication
differentiate into subtypes of helper T-cells:
- Th1: cellular pathway
- Th2: humoral pathway
- Treg: peripheral tolerance
- Memory cells
helper T-cells initiate maturation of B- and T-cells:
facilitation
assist effectors via cytokines
3 key signals for activation of Th cells
- MHC II molecule presenting antigen
- Co-stimulatory signals
- Cytokine stimulation by APC
cytotoxic t-lymphocytes (CD8+):
- activated by ___
- target ____
- does not involve ____
MHC I-antigen complex, assisted by Th1 subtype;
infected, damaged, non-self cells (virus, cancerous, those without correct MHC I molecules like transplanted tissue);
antibodies
3 key signals for activation of Tc cells
- MHC I molecule presenting antigen
- Co-stimulatory signals
- Cytokine stimulation by Th1 cells
cell-mediated immunity targets
- intracellular microbes
- cancer cells
- pathologic responses
regulatory T-cells:
- subset of ____
- provide _____
- prevent _____
helper T-cells;
peripheral tolerance;
over-activation of immune system
peripheral tolerance
- target self-reactive lymphocytes that escape the clonal deletion process or mutate later in its life and are now not able to recognize “self”
- shut down self-reactive lymphocytes once they are out
