quiz 3.2 immuno Flashcards
contact bet B cells and antigen causes B cells to develop
AFC antigen-forming cells aka plasma cells
secretes anibodies in sginificant quantities
plasma cells
antibodies make up ___ of all plasma proteins
20%
what fraction of serum under ung immunoglobulins
gamma globulins
basic immuno molecules is composed of
2 light chains and 2 heavy chains
the chains in a immunoglob are held togethere by
disulfide bonds
2 types of L chain
kappa
lambda
the protion that binds the antigen is
variable regions of both chains
immunoglob are folded into compcat repeating segemnts called
domains
the L chain is made up of
1 variable and 1 constant domain
the H chain is made up of
1 variable and 3 or more constant domain
VL segment has how many hypervars
3
Vh has how many hypervars
3-4
the hypervariable regions pero variable segments are called
complementary-determining regions (CDRs)
hinge region is found where
between CH1 and 2
hinge region confers __ to the molecule and allows the arms of the Y-molecule to move independently
flexibility
the carboydrate moietu of immunoglobs are attached to
heavy chains
glycosylation is usually associated with
Fc domain
in IgG molecules, there is an N-linked glycosylation site located at _____ on each of the two CH2 domain
Asn 297
the glycans interact with _____ on the Fc domain that stabilizes the immunoglob
hydrophobic pocket
fragment that binds to the antigen
Fab
the complement fixing fragment
Fc
this fragment binds the macrophasges and other cells
Fc
there are 2 binding sites in the immuno therefore it is called
divalent
pepsin digestion produces
Fab and Fc
papain digestion produces
2 Fab and 1 Fc
consists of a pair of beta sheets each built of antiparallel beta strands connected by a disulfide bond with a hydrophobic core
immunoglobulin fold
___________ present at one end of the structure form a potential binding surface
first three loops (immuno fold)
the hypervar region forms the source of
antigen specificity
the surrounding polypeptide regions between the hypervariable sements are called
framework regions
what comrpises the antigen bidnign site
VL and VH of each arm
type of bond between antigena dn antibody
noncovalent (van der Waals, hydrogen, hydrophobic, ionic salt)
small conformational changes takes place in the VL-VH domain indicating _____
induced fit
which determines the immuno’s isoform
type pf H chain
smallest but most pervalent immuno 70-75%
IgG
which isotyoe has longest halflife
G
only immuno that provides immune protection to the neonate
G
which IgG subtype activates complement efficiently
1 3
which IgG subtype react predominantly with carbs antigns especially of encapsulated bacter
2 4
IgG functions
classical complement pathway
opsonin
ADCC
IgG targets virally infected cells for destruction bu
antibody-dependent cell-medaited cytotoxicity
% of IgM in the pool
10%
oldest class of immuno and first to develop
IgM
the units in IgM ios held together by
J chains and disulfide bonds
can IgM penetrate tissue fast
no no no way
why is IgM most efficient at agglutinating bacteria
10 antigen-binding sites, 5 complement binding sites
the major antibody in an early imune response
IgM
the natural isohemaglutinins are of what isotype
IgM
main immuno in secretions
IgA
IgA, bcoz dominant in secretions, is also called
mucosal antiseptic paint
IgA mkes up __ of the pool
15-20%
IgA in secretions exist in what form
dimer
where does activation of B cells to produce IgA occur
mucosa-associated lymphoid tissue (MALT)
action of IgA in the mucosa
prevents attachment of bacte (neutralize), does not fix complement
IgD accounts for ____ of the pool
1%
forms a major component of the sufrace membrane of B cells
IgD
synthesize by antigen-sensitive B lymph but not secreted
IgD
in the membrane of B cells, IgD serves as
cell surface receptor
found in the surface mebrane of basophils and mast cells
IgE
for allergic reactions and parasitic shit immuno
IgE
IgE provides an antigen-sensitive means of eliminating intestinal parasites by
increasing vascular permeability and inducing chemotactic factors by mast cell degranulation
determines antibody diversity
multiple genes
variable recombination
somatic mutations
junctional diversity
dse of low IgE
ataxia-telangectasia
dse of inc. IgD
multiple myeloma
multiple myeloma shows inc.
D A G E
where are complements synthesized
liver
components of the classical pathway
C1 2 3 4
components of the alternative pathway
c3 factor B D properdin
component of the membrance attack complex
C5-9
active component fo the clssical pathway that binds the antigen and activates C1r
C1q
active component fo the clssical pathway that cleaves C2 and C4
C1s
active component fo the clssical pathway that cleaves C1s to activate protease function
C1r
active component fo the clssical pathway that cleaves C3 and C5
C2b
active component fo the clssical pathway that mediates inflamm and is an anaphylatoxin
C3a
active component fo the clssical pathway that binds cell surface for opsonization and activation of alternative pathway
C3b
active component fo the alternative pathway that is cleaved by factor D
factor B
active component fo the alternative pathway that binds and stabilized membrane bound C3bBb
properdin
initiates assembly of MAC
C5b
ploymerizes around C5b678 to forma channel that causes cell lysis
C9n
forms accepor for C7
C6
forms acceptor for C8
C7
functions of complements
opsonization cell lysis chemotaxis inc. vascular perm cause smooth muscle contr. promoting msat cell degranulation
process making the abcteria more susceptible to phagocytosis by making recognition easier
opsonization
process directly destroying bacteria and foreign cells
cell lysis
producing substances that attract neutro an d macro for subsequent opsonization and phagocytosis
chemotaxis
the proenzyme activation splits the complement into
small ‘a’ and big ‘b’
the ‘b’ part has 2 biologically active sites
binding cell membrane
cleavage of next component
possess biological properties in the fluids phase that contribute to the inflammatory response
small ‘a’
complement enzyme that converts an inactive complement into an active one
convertase
antibody binding triggers the early complement components ________ while microbial ploysacchs activate ______
C1 2 4
factor B and D
3 major steps in complement system
activation of C3 convertase to cut C3
activation of C5 convertase to cut C5
formation of MAC
\3rd route of C3 activation aside from classical and alternative
mannan-binding lectin pathway
C3 contains ______ between _________
internal thioester bond between glutamine-COOh and cysteine-SH
hydrolysis of C3 by water produces
C3i
a loosely bpund complex that assembles on cell surface-bound Ag-Ab complex
recognition unit
reaction of IgM or G causes a conformational change in the Fc region of the antibody to reveal binding site for
C1q
recogniton unit is composed of
C1qrs
C1q actual
amplifies recognition unit through the proteolytic cascade and concentrates the site of complement activation
activation unit
the activation unit is composed of
C2 3 4
appeareance of C1q
tulip flower
y-shaped w/ globular heads, triple helix
C1q subunit
the intact C1q is made up of ___ subunits
3
intact C1q is rich in ____ and ____
hydroxyproline and hydroxylysine
the catalytic sites of C1r are close to
center of the ring
activation/binding of Ig to C1q results in
conform change
autocatalysis on one C1r
cleavage of other C1r
cleavage or C1s
the cohesion of the complex of recog unit is dependent on
Ca
IgM when bound to antigens on bacterial surface assume what form
staple
C1q must bind to ______ IgG molecule/s
at least 2
binding of C1q to Ig activates C1r which cleaves and activates the serine protease, ____
C1s
in the presence of ___, the compelement C2 binds to C4b present on the bacterial cell surf forming the ____
Mg
C4b2a complex ala C3 convertase
C2 is cleaved to C2a and b by ________ when it is bound to the C4b
C1 complex
which fragment of C2 plays a role in increased capillary permeability
C2b
C2a remains bound to C4b
C3 convertase is
C4b2a
the step whee the C3 convertase cleaves C3 into C3a and b also generates _________
C4b2a3b (C5 convertase)
the C5 convertase or C4b2a3b initiates __
final lytic pathway, ‘attack’ sequence
why is alternative pathway inefficient in tissues
need of high conc. of components
the alternative pathway does not need the action of antibodies to inititate but it is initiated by
foregin cell surface
the alternative pathways involves
C3 to C9
factors B D and P
low levl hydrlysis of the itnernal thioester bond of C3
C3 tick over
this is the alternative pathwya’s C3 converatse
C3bBb
spontaneous cleavage of C3 in the alternae pathway reulst to
binding of factor B (to C3b)
what extends the halflife of C3 convertase in the alternatie pathway
properdin
the C5 convertase of the alternate pathway is
C3bBb3b
most important activators of alternate pathway
bacterial cell wall and endotoxins
difference of mannan-binding lectin from classical pathway
C1q does not participate
what particiates in mannan-binding lectin pathway instead of C1q
MBL, an opsonin
in the MBL pathway, what activaetst the complements
MASP (MBL-associated serine protease)
MAC is
C5b6789
initial step in formation of MAC
cleavage of C5 by C5 convertase (C3bBb3b or C4b2a3b
properties of the the C5 convertase
chemotactic
anaphylatoxin
C5b depsoited in the cell wall forms lipophilic complex with C6 7 to initiate MAC formation
when the lytic pathway complex binds to the cell embrane., _________ is formed
transmembrane channel
pruprose of transmembrane channel in the final lytic pathway
influx of water, electrolytes > swelling > rupture
regulatory protein or mechs of the complement cascades
C1 inhibitor
protein H
factor I
inhibits production of C3b by combining with and ianctivate C1r and C1s
C1 inhibitor
by combining with and ianctivate C1r and C1s, the C1 inhibitor specifically prevents
formation of C3 convertase C4b2a
C1-INH or C1: which is mas madami
C1-INH
inhibits production of C3b by inhibiting the binding of factor B to membrane-bound C3b, thereby preventing cleavage of B to Bb and formation of C3 convertase C3bBb
protein H
the inhibitor in the classical pathway
C1 inhibtior
the inhibitor in the alternate pathway
protein H
factor I only works on
cell mmbrane bound C3b
inhibits production of C3b by cleaving C3b into C3c and C3d
factor I
what are the proteins that regulate the terminal pathway of complement
CD59
HRF
S-protein
S protein is aka
vitronectin
the presence of CD59 HRF and S protein ________
prevent formation of MAC
inhibits the insertion of C567 of mAC
S-protein
action of S-protein
inhibits insertion of C567
group of molecules displayed onc ell surface that are rsponsible for lymphocyte recognition and antigen presentation
MHC
MHC is responsible for ____ and ____
lymphocyte recog and antigen presentattion
MHC proteins were discovered due to their role in
transplantation rejection
where is the gene for MHCs encoded
chrom 6
class 1 MHC is encoded by
BCA region
class 2 MHC is encoded by
D segment
class 3 MHC is encoded by
region bet. BCA and D region
the heavy chain peptide of the MHC1 is controlled by BCA while the smaller chain is controlled by
gene in chrom 15
which chain in the MHC1 is variable
alpha chain - variable
B2-microglob - constant
MHC1: a _________ section anchors the molecule in the membrane and a short _____ sequence carries the C-terminus into tnhe cytoplasm
hydrophobic
hydrophilic
the largest part of the heavy chain is organized into three globular domains (_______________) which protrude from the cell surface
alpha1-3
genes that control the HLA-A B and C are found in
chrom 6
which domain of the MHC1 is noncovalently bound to the B2-microglob
alpha 3
what binds to the alpha 1 and 2 of the MHC1
small antigenic peptides
most nucleated cells express what class of antigen
MHC-1
MHC-2 is encoded by
D region
how many domains seen in the chains of MHC-2
2 each
the groove where the short amino acids, presented to T cells, bind to is called the ____________,
antigen eptiope
variable classes of MHC-2
HLA-DP DQ DR
expression of MHC-2 antigens is restricted to which cells only
dendritic cells B lymphocytes activated T cells macrophages inflamed vascular epithelium APCs
target for presentign antigen: MHC class 1
CD8+ cytotoxic T cells
target for presenting antigen: MHC class 2
CD4+ helper T cells
type of antigen prsented by MHC-1
endogenous - fragments of viral or tumor protein
type of antigen presented by MHC2
exogenous - fragments of bacterial cells or virus
MHC class 3 is composed of what priteins
C4 and C2
factor B
