immuno: antibodies

produced in response to an antigen

what is an antibody

• soluble b cell proteins

• plasma cells

where do antibodies come from

• specific binding

• elimination

how antibodies work

body fluids and serum

where do antibodies located

• detectable reaction

• b cell receptors

detection and receptors

glycoproteins

antibodies are __

antibody

specific binding defines an __

immunoglobulin

__ refers to the activity

structural

immunoglobulin is a __

biological

antibody is a __

IgG

IgM

IgA

IgD

5 groups of immunoglobulins

heterogenous group

immunoglobulins are __ (20% of plasma proteins)

Electrophoretic Mobility

molecular weight

antigenic structure

immunoglobulin may be classified on the basis of

albumin

alpha

beta

gamma

in 1938, Tiselius and Kabat used electrophoresis to separate serum proteins into four distinct groups

molecular weight

using an ultracentrifuge, scientists measure how fast molecules sink (sedimentation)

Svedberg Units (S)

molecular weight is measured in __

Gamma

Meio

Alfa

Delta

Epsilon

antigenic structure

heterogenous glycoproteins

chain composition

the “y” shape

molecular architecture

heterogenous glycoproteins

large group of closely related glycoproteins with molecular weight of approx. 160 KDa

chain composition

• 4 chains

• 2 larger heavy chain (50-60 KDa)

• 2 smaller light chains (25KDa)

disulfide bonds

chains are joined by __ (-S-S-), creating the characteristic of “y” shaped apprearance

B-Cell Membrane

the carboxy (C) terminus of heavy chains is often inserted in the __

450 amino acids

alpha and gamma consist of __

550 amino acids

meio and epsilon consist of

3 constant domains + hinge reaction

gamma, alpha, delta contain __

4 constant domains and lack of hinge reaction

meio and epsilon classes contain __

110 amino acids

approx. ___ long per domain

kappa and lambda

two types of light chain characteristic

one variable and one constant

each light chain of two domains __

cattle or horse

95% lambda in __

rats/mice

95% kappa in __

humans

60% kappa in __

25 KDa

approx. __ per light chain

hotspot

complementarity determining regions (cdrs) is also known as __

complementarity determining regions

the variable region contains areas of extreme variability known as __

24-34

50-56

89-97

specific positions of cdrs

CDRs loops

stable peptide sequences located between the __

n-terminus

binding site formed by the groove created between light chains and heavy chains a their __

CH1 and CH2

hinge region located between __ domains; unique for each class and subclass

Fab regions

allows __ to swing freely around the central molecule

proline

region is hydrophilic and extremely rich in __

cysteine residues

hinge of IgD lacks __

papain

cleaves at hinge by hydrolysis of peptide bonds (proteolytic)

pepsin

cleaves towards the carboxy terminal side of disulfide bond

flexible hinges

an IgG molecule is characterized by three distinct globular regions linked by __

two fab regions

the “fragment antigen binding” arms

one fc region

the “fragment crystallizable” stalk that mediates biological effector functions

maintain stability

these regions allow the molecule to __ while performing complex recognition tasks

mechanical flexibility

The Hinge Region in the middle of heavy chains provides critical mobility. This flexibilty allows

the two fab arms to move independently to reach distant epitopes on an antigen surface

proteolytic vulnerability

The exposed peptide chains in the hinge are highly susceptible to breakage by proteases.

This structural feature is often exploited in laboratory settings to cleave IgG into Fab and

Fc fragments.

fab domains

fc domains

domain pairing

paired domain organization

fab domains

Each Fab consists of two pairs of domains: VH-VL (Variable) and CH1-CL (Constant). These chains are closely intertwined.

fc domains

Contains paired constant domains: CH-2-CH2 and CH3-CH3. IgE or IgM classses feature an additional CH4-CH4 pair.

domain pairing

The specificity of the antibody is determined by how these variable domains fold together to form a unique surface.

cdr specificity

A specialized groove is formed between the two variable domains, VH and Vl. This groove forms the actual antigen-binding site of the antibody.

two identical antigen-binding sites

Because immunoglobulins are bilaterally identical, the CDRs on each Fab region are also identical. This means a single IgG molecule possesses __

bivalency

This __ allows the molecule to bind two identical epitopes, facilitating the cross-linking of antigens into large immune complexes.

dual chain contributions

The CDRs from both light and heavy chains contribute to binding, though heavy chain usually contributes the most.

antigen cross-linking

since binding sites are identical, antibodies can bridge two separates antigens simultaneously

geometric precision

the specific folding of peptide chain creates a topographical match for the epitope, ensuring high affinity

human IgG4

unlike other substances, __ is dynamic

hybrid antibodies

human IgG4 can exchange regions with other iGg4 molecules to generate __

IgG

highest concentration in blood

IgM

second highest serum concentration (in most mammals)

IgA

Third highest concentration in most mammals. The predominant Ig in secretions such as SALIVA, MILK, & INTESTINAL FLUID

IgD

primarily a BCR, rarely encountered in body fluids

IgE

very low concentration in serum and mediates allergic reactions

spleen, lymph nodes, bone marrow

igg produced by plasma cells in the __

immunoglobulin g

• 180 kDa

• smallest of ig molecules

• important in inflammation

secondary lymphoid organs

igm produced by plasma cells in __

B-Cells

Secreted (Blood)

two different forms of igm

immunoglobulin m

• Major Ig produced during primary immune response

• More efficient than IgG at complement activation, opsonization, neutralizing of virusws, and agglutination.

intestinal tract

respiratory tract

urinary tract

mammary gland

skin

iga present mainly in the __

colostrum, saliva, tears

major immunoglobulin (a) found in __

mucosal surfaces

iga provides local immunity at __ (respiratory and intestinal tracts)

alternative pathway

iga does not activate the classical complement pathway, but can activate the __

phagocytosis and intracellular killing

iga enhances __

coproantibodies

iga known as __ when found in gut contents or feces

serum iga

secretory iga

2 types of IgA

immunoglobulin e

synthesized by plasma cells located beneath body surfaces

reaginic antibody

binds to mast cells and it triggers degranulation and release of inflammatory mediators

type 1 hypersensitivity

ige immediate allergic reaction

parasitic worms

ige provides defense against __

immunoglobulin d

secreted by plasma cells in spleen and lymph nodes

maturation

antigen challenge and binding

clonal selection and proliferation

differentiation

antibody production and secretion

steps on maturation of b cells

any substance that triggers an immune response

antigen = __

epitopes

specific parts of antigens called __

hydrogen and ionic bonds

antigen uses weak forces like __

one antigen

each antibody matches __

high affinity =stronger binding

neutralization

agglutination

precipitation

opsonization

types of reactions of antigens

neutralization

blocks toxins/virus

agglutination

clumps pathogens

precipitation

forms sold complexes

opsonization

enhances phagocytosis

complement system

antibodies activates __

immune cells

antibodies attracts __ and leads to inflammation

protects body from infection

used in vaccines

important in lab tests/diagnostics

importance of antibodies

specific

antigen-antibody binding is __

immune defense

antibody triggers __