lecture 1 Flashcards
what are the sources of infection?
-pathogens
-bacteria
-viruses
-funghi
-parasites
-worms
-protozoa
what features does the immune response need to be effective?
- be able to recognise and respond to invading organisms
- not over-react to benign or self pathogens
- be able to direct different effector mechanisms against different pathogens
what is specific/adaptive immunity?
-induced by exposure
-shows high degree of specificity
-exhibits memory
what are the features of specific immunity?
-mediated by lymphocytes
-clonally distributed receptors
-clonal expansion once antigen found that receptor has recognised
what is the clonal selection theory?
-allows lymphocytes that potentially bind ourselves are removed
-has receptor that recognises self antigen so during development those cells die
-foreign antigen induces cell to clonal expand to form identical cells scan respond to the antigen
what is BCR expressed by?
B lymphocytes
where binds the ‘free’ antigen?
membrane form of Ig
what is TCR expressed by?
T lymphocytes
how are TCR recognised?
-recngoises peptide fragment of antigen bound to MHC expressed by APC
what are the properties of the T lymphocyte receptors for TCR?
-smaller receptor domain
-alpha and beta chain
-membrane anchored
-never secreted, is always on the surface of T cells
-only recognises short peptide fragments (doesn’t recognise when floating alone-have to be encoded within the MHC)
what does MHC stand for?
major histocompatibility complex molecules
what is the difference between class l and class ll MHC molecules?
class l = expressed by nearly all cell types, alpha 1,2 and 3 domain which associate with beta-2 micro globulin
class ll - expression restricted to specialised group of immune cells, alpha and beta chain
what are the properties of class l?
-heterodimer
-expressed on all nucleated cells
-HLA-A, HLA-B, HLA-C
what 2 regions are polymorphic?
alpha 1 and 2
what 2 regions fold into Ig like domains?
alpha 3 and beta 2
