Ag Receptors: Lymphocytes Flashcards Preview

HDM Midterm > Ag Receptors: Lymphocytes > Flashcards

Flashcards in Ag Receptors: Lymphocytes Deck (38):
1

Ag

molecule that is recognized by the immune system. loosely associated with adaptive response

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immunogen

an Ag that evokes a specific immune response

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tolerogen

an Ag that induces immunologic tolerance

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Endogenous

body's own cellular components or intracellular pathogens

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auto-Ag

self-Ag

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allo-Ag

tissue specific Ag

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Exogenous Ag

Ag enter the body or system and freely circulate in the body fluids and are trapped by the APCs

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haptens

small molecules which cannot induce an immune response alone
induce a response when coupled with a carrier protein

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BCR components

Surface Ig
IgBeta and IgAlpha (signaling - contain ITAMs)

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Ab do two things

promote killing/removal of Ag-Ab complex
integral in B cell differentiation

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digestion pdt of papain and pepsin

papain - cuts above the hinge == 2x Fab, Fc
pepsin - cuts below the hinge == 1F(ab')2, fragments

12

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

13

the isotype of an Ab is determined by

the heavy chain (c domain)

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allotype

subtle allelic differences exist within H chains - important for transplantation

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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)

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J chains are present on

IgA and IgM
JAM

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Ab class produced by neonates

IgM

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first Ab class produced in primary response

IgM

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Ab isotype that contains 10 binding sites

IgM

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Ab type expressed on the surface of mature activated B cells

IgM or IgD

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predominant Ab isotype of secondary immune response

IgG

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most abundant IgG subclass

IgG1

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Ig classes that activate classical complement

IgM
IgG
(may be more but these for sure)

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predominate Ig class of mucosal immunity

IgA

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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)

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Ab isotype involved in defense against hilminth

IgE

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Ab isotype which Fc region binds CD23

IgE

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affinity vs avidity

affinity is the strength of a single interaction
avidity is the additive strength of multiple Ag-Ab interactions

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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

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t dependent Ags are

always proteins

31

t independent Ags can be

polysaccharides, lipids (usually multiple identical epitopes that can cross link BCRs)

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most variable region within TCR

CDR3 (v region contains 3 hypervariable regions, of which 3 is the most variable)

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gamma/delta T lymphocytes are primarily located in the

epithelial/mucosal compartments
not MHC/HLA restricted
can recognize lipid Ags and DAMPs

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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)

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TCRs recognize protein in what conformation

primary sequence, only when presented
free peptides are not recognized by TCRs

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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

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superAg manifest in

staph enterotoxins (food poisoning)
staph toxic shock toxin (TSS)
staph exfoliating toxins (scalded skin syndrome)
strepto pyrogenic exotoxins (shock)

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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