Adaptive Immunity Flashcards
Where does recognition of a pathogen occur?
secondary lymphoid tissue - lymph node or spleen
T-cell receptor
recognizes peptides presented by MHC molecules
What type of receptors have constant and variable regions?
both BCR and TCR
What regions do B-cells have?
heavy and light chains
What regions do T-cells have?
alpha + beta
delta + gamma
What is an antibody?
a B-cell receptor floating free
What region of receptor binds an antigen?
variable region
Antibody isotope
constant region which determines the mechanism to kill the antigen
How many constant regions are there?
5 different types of constant regions (Ig)
IgM
constant region that activates complement system
IgA
protects mucosal surface
IgG
most commonly circulating in plasma
Clonality
cell that recognizes a pathogen will divide when exposed to that pathogen
need more of that specific pathogen to fight!
How do lymphocytes create specificity and diversity in antigen binding sites?
through VDJ or VJ rearrangement
VDJ rearrangment
rearrangment of DNA in heavy/beta chains to create antigen specificity
VJ rearrangment
rearrangment of DNA in light/alpha chains
MHC restriction
T-cell does not directly recognize antigen
need the antigen to be presented on a MHC molecule
What is presented through MHC?
a peptide in the pocket
Where are MHC I receptors?
on all cells
Where are MHC II receptors?
only on antigen presenting cells: macrophages, dendritic cells, B-cells
What cells recognize peptides presented by MHC I?
cytotoxic T-cell, CD8
What cells recognize peptides presented by MHC II?
helper T-cells, CD4
What type of antigens do MHC I present?
intracellular (viruses, obligate intracellular bacteria)
What type of antigens do MHC II present?
extracellular antigens taken up into the cell by endosomes
MHC I steps to present an antigen
1) protein is in cytosol (intracellular)
2) degraded into peptides by proteasome
3) peptides go to ER then TAP
4) loaded into MHC I
TAP
allows antigens to go from ER to membrane for receptor on MHC I
MHC II steps to present an antigen
1) endocytosis of extracellular pathogen
2) degraded into peptides in an endosome
3) loaded into MHC II
Why are dendritic cells professional antigen presenting cells?
they can use MHC I and MHC II receptors
they can activate naiive T-cells
neutralizing antibodies
bind to pathogen and pathogen is removed before host is infected
Do we need T-cells to create antibodies?
Yes, for the most successful ones!
T-cells can help B-cells to produce a better antibody
Adjuvant
extra material included in vaccines to help spur immune response to vaccine
activates innate immunity
What is required for antigenic shift to happen?
segmented DNA
Why can’t RSV do antigenic shift?
because it is nonsegmented
Molecular mimicry
pathogens may result in autoimmune response
similarities between foreign and self-peptides makes T/B-cells likely to attack the self
IgE
activates allergy response
