Adaptive Immunity Flashcards
adaptive immunity: characteristics (2)
- disease/antigen specific
- memory
adaptive immunity: what processes are involved (3)
- clonal selection
- clonal expansion
- results in amplification of immune response
adaptive immunity: speed (2)
- initially slow
- more rapid in later stages
adaptive immunity: types (2)
- humoral
- cellular
cell-mediated immunity responses
- T cells attack infected body cells that display antigen of pathogens on surface
humoral immunity
- B cells produce antibodies after activation by soluble antigens
adaptive immunity: cell types (3)
- B cells
- T cells
- antigen presenting cells (APCs)
antigen presenting cells (3)
- dendritic cells
- macrophages
- B cells
how does the adaptive immune system achieve diversity
- millions of B and T cells with unique receptors for recognizing antigens
B cell receptors (2)
- surface IgM
- surface IgD
what do B cell receptors recognize
- soluble antigens
what do T cell receptors recognize
- peptide antigen in conjunction with major histocompatibility complex (MHC)
clonal selection
- expansion of a single B or T cell after its receptor is engaged
clonal selection: result (2)
- development of specific effector cells
- development of memory cells
clonal selection: specific effector cells (3)
- plasma cells that produce antibodies
- cytotoxic T cells (CD8+)
- helper T cells (CD4+)
clonal selection: memory cells (2)
- activated more easily and quicker
- long-lived
antigen presentation: pathogen/large protein taken up by APC (5)
- once in the cytosol, the bacterial proteins will be degraded by proteasome to produce peptides
- peptides transported to the lumen of the ER via TAP transporter
- peptides associate with MHC class I
- complex transported to cell surface
- complex now interacts with T cell receptor (TCR) on CD8+ cells
antigen presentation: what is used to transport peptides to the ER lumen
- TAP transporter
antigen presentation: soluble antigen taken up by APC (5)
- antigen in endosome is trafficked to the lysosome
- proteins are degraded in the lysosome
- vesicles containing peptide will fuse with vesicles containing MHC Class II
- complex traffics to cell membrane
- complex engages with TCR on CD4+ T cells
antigen presentation: CD8+ cells (2)
- engage with MHC Class I complex
- associated with whole pathogens/proteins found in APC cytosol
antigen presentation: CD4+ cells (2)
- engage with MHC Class II complex
- associated with antigens taken up by endocytosis
cytotoxic T cells (Tc): recognition
- recognize Ag in conjunction with MHC CI
cytotoxic T cells (Tc): role (2)
- Tc gets activated and kills target cells
- produce interferon-γ (IFN-γ)
how do cytotoxic T cells kill target cells (2)
- via perforin and granzyme
- leads to apoptosis of the target
INF-γ (2)
- activates macrophages
- produced by activated cytotoxic T cells
T helper cells (Th): role (2)
- secrete cytokines
- type of effector response depends on pattern of cytokines they secrete
Th1: main role
- contribute to inflammatory response
how do Th1 cells contribute to inflammatory responses (3)
- attract and activate macrophages
- activates Tc
- make IFN-γ and TNF-α
Th2: main role (2)
- provide help to B cells (humoral response- Ab) for T-dependent antigens
- make IL-4 and IL-5
what are the humoral responses (5)
- Ag will interact with B cells via BCR
- B cells take up Ag
- Ag is processes and presented in context of MHC CII
- activated T cell produces IL-4 and IL-5
- B cell proliferates and differentiates into plasma cells that produce specific antibodies
humoral response: BCR:Ag interaction signals (2)
- signaling via BCR
- signaling via interaction with T cell (co-stimulatory molecules and cytokines)
humoral response: B cell and T cell co-stimulation molecules (2)
- CD40 on B cells
- CD40 ligand on Th2
humoral response: which T cells produce IL-4 and IL-5 (2)
- cytokines are produced by T cell that recognized the same Ag that was recognized by the B cell
- called Linked Recognition
humoral response: activated of B cell results (2)
- memory B cell
- plasma cell that produces Ab
antibodies: roles (3)
- neutralize the antigen
- opsonization
- activation of the classical pathway of C’
antibodies: types (2)
- monoclonal vs polyclonal
- T-dependent vs T-independent
polyclonal antibodies
- antibodies that bind to the same antigen at different epitopes
monoclonal antibodies
- antibodies that bind to the same antigen at the same epitope
antigen components (4)
- heavy chain
- hinge region
- light chain
- antigen binding site
antigen components: constant portion (2)
- heavy chain
- hinge region
antigen components: variable portion (2)
- light chain
- antigen binding site
T-dependent antigens
- B cells cannot under activation without help from helper T cells through co-stimulation
T-independent antigens
- B cells can undergo activation without help from T cells
Haemophilus influenzae B (Hib) (2)
- causes meningitis
- results in intellectual disability, deafness, or seizures
Hib: immune response
- protective immune response mediated by antibody against capsular polysaccharide
Hib: immune response in adults vs babies (2)
- adults make an effective immune response to capsule
- babies have immature immune system and do not make T-independent immune responses
how to turn a T-independent Ag to a T-dependent Ag (2)
- make a conjugate vaccine
- link the polysaccharide to a protein that does induce T-dependent B cell activation
Hib vaccine (3)
- Hib capsular polysaccharide is linked to tetanus/DT toxoids
- engage T cells that recognize the toxin and B cells that recognize the polysaccharide
- T cells provide help to B cells, leading to affinity maturation and production of both plasma cells and memory B cells
