Intro immunology Flashcards
cause of type 1 diabetes
destruction of insulin producing B-cells
what is autoimmune disease
adaptive immune response that becomes directed at self
what is normal function of immune system
distiguish self from non self and destroy non-self
what are 2 lines of innate defence
- anatomic
2. chemical/cellular
what are 2 anatomic defecnes
- physical barriers (skin)
2. mech. barriers (sneeze etc.)
what are 5 C’s of second line of defence
- cellular
- cytokines - chems that make cells do things
- complement - help other systems
- chemokines - chemicals that cause cells to migrate
- coagulation -
what are cells involved in cellular defence
granulocytes, monocytes, NK cells
3 keys points to innate immunity
- early recognition
- non-specific
- Activatyion leads to killing, cytokine release, connects to adaptive
how does macrophage recognize a pathogen
TLR-4 Toll like receptor on surface can recognize pathogen
what does phagocytosis lead to
- degradation in lysosome
- display of antigen on cell surface
- induction of pro-inflammatory cytokines
3 important non WBC innate cells
- mast cells - early sentinels
- polymorphonuclear cells - main job to phagocytose
- NK cells - early viral defense
what are 3 functions of complement cascade
- tag pathogen for phagocytosis (opsinization)
- promote inflammation
- poke enzyme holes in pathogen to kill
main function of adaptive immunity
refine and strengthen system
when does adaptive system come into play
when innate does not terminate
2 main cells of adaptive system
B and T cells
2 main types of T cells
humoral and cell mediated
2 types of adaptive immunity
- humoral - B-cells
2. cell mediated - T-cells
where do B cells develop
in bone marrow
what happens when B cells contact antigen
proliferate into plasma cells that secrete antibodies
where do T cells come from
produced in bone marrow and mature in thymus
what happens when T cell comes into contact with antigen
proliferate into effector T cells
how many antigens can lymphocytes respond to
one - all clones
what is B cell receptor
immunoglobulin that will be expressed as the ultimate antibody
what keeps BCR bound
trans membrane protein
what are 2 functional divs of BCR
- variable region (what binds)
2. constant region
what is make-up of BCR
2 heavy and 2 light chains
what is antibody
BCR without tail attaching
what must a TCR have to work
co-receptor (CD4 or CD8)
how does TCR see antigen
peptide in form of MCH on antigen presenting cell
where are 2 classes of MHC molecules found
- most nucleated cells
2. antigen presenting cells
what are co-receptors for to MHC classes
- CD8
2. CD4
what is the function of the MHC protein
define the cell as self
what is a haplotype
our unique set of MHC genes
where does our haplotypes come from
one allele from each parent
what is T cell MHC restriction
only recognize peptide antigen in the scaffold of self MHC
what is T cell positive selection
in thymus, T cells can only continue to develop if they recognize self MHC on nearby stromal cells
what are specifc and non-specific parts of antibody
specific - variable region that bind pathogen
non-specific - constant region that bind to receptor on immune cells
what does antibody opsiniization do
make the antigen more delicious and easy to phagocytose
what are (4) CD4 helper t-cells and functions
Th1 - intracellular pathogens - produce cytokines to activate macros
Th2 - extracellular pathogens - produce cytokines for humoral immunity
Th17 - extracellular bacteria - implicated in autoimmunity
Treg - regulatory
CD8 functions
direct killing
how does immune system have memory
keeps some surviving memory cells that can be quickly reactivated
what is diversity
ability to respond to many different organisms
most important way to generate diversity
production of B and T cell receptors
how is TCR made unique
somatic recombination of the variable region
what does this recombination create
each lymphocyte as a unique receptor
what is problem with random recombination
can potentially make a receptor for self antigen
at what level does tolerance occur
level of adaptive immunity
where does tolerance occur for T and B cells
B -bone marrow
T - thymus
what is method of B cell tolerance
negative selection - if recognizes self - terminated
what are steps for T-cell tolerance
- postive selction - keeps cells that recognize self MHC
- negative selection - elim cells that recognize self-peptides (too tight)
- peripheral mechanisms to deal with ones that escape
what is main function of inflammation
enables immune cells to come to infected tissue rapidly
problems with inflammation
causes tissue damage and if not fixed can cause irreparable damage
what CAN cause chronic inflammation
autoimmunity - presence of non-infectious antigens that are stimulating an immune response
what does autoimmunity develop from
failure to develop tolerance mechanisms
2 types of mechanisms that contribute to self-tolerance
- central
2. peripheral
3 features of central mechanisms for self-tolerance
- negative selection
- expression of tissue specific proteins in the thymus
- generation of Treg cells
3 features of peripheral mechanisms for self-tolerance
- suppression of autoimmune responses by Treg cells
- induction of anergy in autoreactive cells
- immune privledge
how are tissue specific proteins expressed in the thymus
dendritic cells carry “systemic” antigens to thymus via soluble serum proteins
what is gene that enables thymic cells to to produce self-proteins
AIRE gene - internal image of self
what do Treg cells do
inhibit T cells and effector T cells that recognize self antigen
what other regulatory cells exist
B cells and for most other immune cell subsets
what 2 things are requires for naive T cell activation
- antigen specific stimulation
2. costimulation signal
how does T-cell become anergic
lack of costimulations
what happens in anergy
functional unesponsiveness
what is immune privledge
tissues that have evolved to be protected from the immune system
what tissues have immune privledge
brain, eye, testes, placenta, fetus
what are 2 mechanisms of immune privledge
- mechanical factors - barriers
2. active factors - immunosupressive molecules
when is immune privledge a problem
when exposed, they do not have self antigen and are seen as foreign
5 general concepts in autoimmunity
- results from failure of T and B cells to develop tolerance
- main contributing factors are genetics and env. triggers
- various effector mechanisms are responsible for tissue damage
- may be systemic or organ specific
- tend to be chronic and progressive
5 main types of T cells
- helper
- cytotoxic
- memory
- regulatory
- natural killer
what are the effector mech in autoimmunity (2)
same as regular attack
- chronic inflammation
- interference with tissue function
4 types of autoimmune reactions
- autoantibodies against self
- antigen immune complexes deposited in organs
- autoreactive T cells against self
- combo of the above
