Ag Receptors: Lymphocytes Flashcards
Ag
molecule that is recognized by the immune system. loosely associated with adaptive response
immunogen
an Ag that evokes a specific immune response
tolerogen
an Ag that induces immunologic tolerance
Endogenous
body’s own cellular components or intracellular pathogens
auto-Ag
self-Ag
allo-Ag
tissue specific Ag
Exogenous Ag
Ag enter the body or system and freely circulate in the body fluids and are trapped by the APCs
haptens
small molecules which cannot induce an immune response alone
induce a response when coupled with a carrier protein
BCR components
Surface Ig
IgBeta and IgAlpha (signaling - contain ITAMs)
Ab do two things
promote killing/removal of Ag-Ab complex
integral in B cell differentiation
digestion pdt of papain and pepsin
papain - cuts above the hinge == 2x Fab, Fc
pepsin - cuts below the hinge == 1F(ab’)2, fragments
within each variable domain of an Ab exists three
hypervariable domains on the most distal portion of the Ab from the constant region
most important region for binding Ag
the isotype of an Ab is determined by
the heavy chain (c domain)
allotype
subtle allelic differences exist within H chains - important for transplantation
idiotype
Ag determinants of variable region idiotypes may differ in how they interact with an Ag, but will both recognize it (and therefore have effector function)
J chains are present on
IgA and IgM
JAM
Ab class produced by neonates
IgM
first Ab class produced in primary response
IgM
Ab isotype that contains 10 binding sites
IgM
Ab type expressed on the surface of mature activated B cells
IgM or IgD
predominant Ab isotype of secondary immune response
IgG
most abundant IgG subclass
IgG1
Ig classes that activate classical complement
IgM
IgG
(may be more but these for sure)
predominate Ig class of mucosal immunity
IgA
J chain of IgA and IgM are recognized by what protein for secretion across an epithelial barrier
Poly-Ig receptor
endocytosed with the IgA molecule and secreted with it
Ab isotype involved in defense against hilminth
IgE
Ab isotype which Fc region binds CD23
IgE
affinity vs avidity
affinity is the strength of a single interaction
avidity is the additive strength of multiple Ag-Ab interactions
Epitopes that can be recognized by B lymphocytes/Abs
1) conformational determinant (3d structure)
2) linear determinant (either accessible only when denatured or in both native/denatured forms
3) determinant made available by proteolytic cleavage
t dependent Ags are
always proteins
t independent Ags can be
polysaccharides, lipids (usually multiple identical epitopes that can cross link BCRs)
most variable region within TCR
CDR3 (v region contains 3 hypervariable regions, of which 3 is the most variable)
gamma/delta T lymphocytes are primarily located in the
epithelial/mucosal compartments
not MHC/HLA restricted
can recognize lipid Ags and DAMPs
TCR receptor complex constituents
alpha/beta heterodimer with variable (and hypervariable) regions 2x CD3 (for a total of four ITAMS) 2x delta chains (for a total of six ITAMs)
TCRs recognize protein in what conformation
primary sequence, only when presented
free peptides are not recognized by TCRs
superAg binding and MoA
bind the Vbeta region of TCR and MHC class II molecules hyper-activate immune system to release bio-active cytokines from T cells == cytokine storm with a bunch of nasty effects
superAg manifest in
staph enterotoxins (food poisoning)
staph toxic shock toxin (TSS)
staph exfoliating toxins (scalded skin syndrome)
strepto pyrogenic exotoxins (shock)
mAb are produced by
isolated mouse spleen cells that produce Ab of interest
fusing with immortal myeloma line
culture in selected media (that filters out myelomas/spleen cells that didnt fuse)
isolate clones
success
