34. Humoral Immunity Flashcards
where are B CELLS typically found
BLOOD
LYMPH NODES
SPLEEN
how are B CELLS ANTIBODIES INITIALLY
have ANTIBODIES on their CELL SURFACE,
acting as RECEPTORS for ANTIGENS
what happens when an ANTIGEN BINDS to the ANTIBODIES on B CELL SURFACE
ACTIVATES
PROLIFERATION
drives B cell into a PLASMA CELL - SECRETORY CELL that SECRETES ANTIBODIES into bloodstream
what do some PLASMA B CELLS become after
MEMORY B CELLS
what is the major component of humoral immunity
antiodies
what are the 5 CLASSES of ANTIBODIES
IgA, IgD, IgE, IgG, IgM
(all have same basic structure but some variation)
Ig = Immunoglobulin
what type of molecule are ANTIBODIES
GLYCOPROTEINS
(GLYCOSYLATED)
where are ANTIBODIES found
in SERUM and TISSUE FLUID
Basic STRUCTURE of ANTIODIES - composed of:
2 IDENTICAL LIGHT CHAINS
2 IDENTICAL HEAVY CHAINS
2 IDENTICLE ANTIGEN BINDING SITES
- VARIABLE region
- CONSTANT region
Basic STRUCTURE of ANTIODIES - what is it held together by
COVALENT & NON-COVALENT BONDS
2 HEAVY chains held together by DISULPHIDE BONDS
Basic STRUCTURE of ANTIODIES-
HINGE REGION allows for
FLEXIBILITY
(for binding)
which antibody is the PREDOMINANT ANTIBODY in the PRIMARY immune response
IgM
which antibody is the PREDOMINANT ANTIBODY in the SECONDARY immune response
IgG
IgM has a …. structure
PENTAMERIC STRUCTURE
- 5 basic antibody chains held together by a J CHAIN
what does LARGE SIZE (pentameric) of IgM mean for it
LIMITED TRANSFER to tissues
- mainly in SERUM
- makes up around 10% of TOTAL SERUM IMMUNOGLOBULIN (significant)
what is IgM good for (3)
COMPLEMENT FIXING
NEUTRALISING
OPSONISING antigens
IgG is the PREDOMINANT antibody of which immune response
SECONDARY
STRUCTURE of IgG
MONOMER (basic Y shape)
with 4 SUBCLASSES: IgG1, IgG2, IgG3, IgG4
(vary in hinge regions)
what is the MAIN antibody found in SERUM and TISSUE FLUID
IgG
IgG makes up how much of total SERUM IMMUNOGLOBULIN
75%
IgG binds to Fc RECEPTORS on…(3)
LYMPHOCYTES
MONOCYTES
PHAGOCYTES
ROLES of IgG
OPSONISATION
NEUTRALISATION
PHAGOCYTOSIS
IgA is the PREDOMINANT antibody found in…
SECRETIONS
what is the STRUCTURE of IgA
basic Y shape
but generally DIMER STRUCTURE
- joined by a J CHAIN
- often associated with a SECRETORY COMPONENT
(in circulation it is a MONOMER)
what is IgA DIMER often associated with
SECRETORY COMPONENT
- produced by EPITHELIAL CELLS
IgA is important in what immunity
MUCOSAL IMMUNITY
- found at MUCOUS MEMBRANES
where is IgA found
MUCOUS MEMBRANES in GUT,
RESPIRATORY TRACT,
SKIN
sometimes circulation (as a monomer)
what is IgA good at (3)
NEUTRALISING
BLOCKING pathogen ENTRY
BLOCKING pathogen GROWTH
how is IgE STRUCTURE
MONOMER
(basic Y shape)
how is IgE concentration in SERUM
LOWA
IgE is important in…
ALLERGY
& response to PARASITES
what does IgE do in response to ALLEGREN (antigen)
binds to antigen
& BINDS to FceRI on MAST CELLS
- activates RELEASE of HISTAMINE & INFLAMMATORY MEDIATORS
when IgE binds to FceRI on MAST CELLS what is released (2)
HISTAMINE
INFLAMMATORY MEDIATORS
how are IgD SERUM LEVELS
VERY LOW
how is IgD STRUCTURE and where is it FOUND
MONOMER
at CELL SURFACE of B CELLS
IgD acts as…
an ANTIGEN RECEPTOR on surface of B-cells
- antigen BINDS to it and triggers cell activation
which Immunoglobulin has a PENTAMERIC STRUCTURE
IgM
which Immunoglobulin is found as a DIMER
IgA (mucous membranes)
which Immunoglobulin has 4 SUBCLASSES
IgG (secondary response)
which Immunoglobulins are MONOMERS
IgG, IgE, IgD
IgA in circulation
which Immunoglobulin is important in response to ALLERGY
IgE
which Immunoglobulin is important in MUCOSAL IMMUNITY (at mucous membranes of gut, respiratory tract, skin)
IgA
which Immunoglobulin acts as an ANTIGEN RECEPTOR
IgD
which Immunoglobulin is good at COMPLEMENT FIXING, NEUTRALISING, OPSONISING
IgM (primary response)
which Immunoglobulin binds to FceRI on MAST CELLS
IgE (response to allergy)
which Immunoglobulin responds to PARASITES
IgE
which Immunoglobulin is found at the CELL SURFACE of B CELLS
IgD (antigen receptor)
which Immunoglobulin binds to Fc RECEPTORS on LYMPHOCYTES, MONOCYTES, PARASITES
IgG (secondary response)
which Immunoglobulin is good at NEUTRALISING, BLOCKING ENTRY, BLOCKING GROWTH
IgA (at mucosal membranes - secretory)
which Immunoglobulin is good at OPSONISATION, NEUTRALISATION, PHAGOCYTOSIS
IgG
which Immunoglobulin makes up 10% of SERUM
IgM
which Immunoglobulin makes up 75% of SERUM
IgG
which IMMUNOGLOBULIN is found predominantly in SECRETIONS
IgA
which Immunoglobulin activates release of HISTAMINE and INFLAMMATORY MEDIATORS
IgE (response to allergy)
where is the primary location of IgM
CIRCULATION
(& sometimes found on B-cells)
where is the primary location of IgG
CIRCULATION
& MOST TISSUES
where is the primary location of IgA in its 2 forms
as a DIMER: MUCOUS MEMBRANES & SKIN
as a MONOMER: CIRCULATION
where is the primary location of IgE (allergy)
GUT,
AIRWAY,
SKIN
where is the primary location of IgD
B-CELLS
how is SECONDARY RESPONSE compared to PRIMARY
FASTER
SHORTER LAG
EXTENDED PLATEU
HIGHER ANTIBODY TITRE
INCREASED AFFINITY of ANTIBODIES to ANTIGEN (AFFINITY MATURATION)
Predominantly IgG (IgA or IgE)
primary = IgM
how is AFFINITY of antibodies to antigens different in primary and secondary immune response
SECONDARY- INCREASED AFFINITY
AFFINITY MATURATION
how do ANTIBODIES help FIGHT INFECTION (2)
NEUTRALISATION
- binding to toxin or virus, preventing it from binding to a receptor on host cell
- IgG, IgA, IgM
ENHANCING Fc RECEPTOR MEDIATED PHAGOCYTOSIS
-OPSONISATION (coating eg bacteria)
- IgG
which ANTIBODY CLASS ENHANCES Fc RECEPTOR MEDIATED PHAGOCYTOSIS (OPSONISATION)
IgG
other ROLES of ANTIBODIES (3)
- Antibody and antigen ACTIVATION of the
COMPLEMENT PATHWAY (classical pathway) - IgE ACTIVATION of MAST CELLS (release histamine & inflammatory mediators). ANTI-PARASITE responses and role in ALLERGY.
(can also bind to FcR on EOSINOPHILS) - TUMOUR CELL KILLING by NK cells and antibody (Fc receptors on NK recognise bound antibody)
which COMPLEMENT pathway ACTIVATION involves ANTIBODIES
CLASSICAL PATHWAY
which are the best ANTIBODIES at ACTIVATING COMPLEMENT
IgM, IgG1, IgG3
COMPLEMENT system results in the FORMATION of
MEMBRANE-ATTACK COMPLEX
ANTIBODIES can INDUCE
ALLERGY
ANTIBODIES are importing in inducing effective…
VACCINATION against pathogens
ANTIBODIES play a role in IMMUNOPATHOLOGY:
AUTOIMMUNE DISEASE
ANTIBODIES are important TOOLS for…
DIAGNOSIS
ANTIBODIES are also being used in…
THERAPEUTICS (treatment)
modern but expensive drugs
what is HUMMORAL IMMUNODEFICIENCY
conditions where an individual is DEFICIENT IN or LACKS the ABILITY TO TO PRODUCE ANTIBODIES
ranges from no antibody to reduced production of one class
e.g. Selective IgA deficiency (SIgAD), reduced IgA levels, a genetic immunodeficiency, (type of hypogammaglobulinemia), affects around 1 in 600 people,
what is AUTOIMMUNITY
PRODUCTION of ANTIODY AGAINST SELF PROTEINS
e.g. Myasthenia Gravis: muscular weakness associated with Abs to acetylcholine receptors.
what is ALLERGY
ANTIBODY PRODUCED AGAINST COMMON ENVIRONMENTAL PROTEINS (eg pollen) which would otherwise be harmless
eg Hay fever, Asthma
ANTIBODIES in THERAPEUTICS are suitable for the TREATMENT of…
IMMUNE / INFLAMMATORY DISEASES or CANCER
- mainly work by NEUTRALISING a molecule important in the disease process.
why do ANTIBODIES have potential to be GOOD DRUGS (4)
- HIGH SPECIFICITY
- well CHARACTERISED STRUCTURE and BIOCHEMISTRY
- seen as NORMAL body component
- can be MADE AGAINST ANYTHING
ANTIBODIES given THERAPEUTICALLY are…
GENETICALLY ENGINEERED MONOCLONAL ANTIBODIES
- antibodies in any one preparation are identical, binding the same part of the antigen
what is the PROBLEM with MONOCLONAL ANTIBODIES being generated in MICE
mouse antibodies are IMMUNOGENIC in humans - cause IMMUNE RESPONSE
fully human antibodies are best but HARDER to generate
example of ANTIBODIES in THERAPEUTICS:
for Respiratory Syncytial virus (RSV)
(Common infection in young children, can
cause serious respiratory disease, no vaccine)
PALIVIZUMAB - HUMANIZED antibodies (mostly human but still got some mouse sequence)
provides PASSIVE IMMUNITY (not long-lasting protection)
- NEUTRALISES the FUSION PROTEIN (viral particle)
