antibodies

A N AT O L I Y T I M O F E E V

N OV I S A D 2 0 1 2

ANTIBODIES

WHAT DID YOU EXPECT?

TERMINS IN USE

• ANTIGEN – three-dimensional protein molecule on the surface of pathogen• PATHOGEN – disease causing agent• ANTIBODY – protein molecule, that is produced by

immune system

ANTIBODIE ARE

Globuline proteins

Immunoglobulines

Gamma – globulines ( )𝞬

IMMUNOGLOBULINE STRUCTURE

IMMUNOGLOBULINES ARE GLUCTOPROTEINS

Made up ofL (light)H (heavy) chains

Weight because of molecular massL = ± 25000H = 50000 ± 70000IgG=2H+2L chains

LIKE A LEGO! IS NOT IT?

2 HEAVY

2 HEAVY+ 2 LIGHT

!!!!+DISULFIDE BOND!!!!

L AND H PARTS HAVE VARIABLE AND CONSTANT CHAINS

FAB- AND FC- FRAGMENTS

CommentFab sites bind antigen(fragment antigen bidning)Fc fragment recognized by complement, phagocytes (fragment constant)

ANTIBODY MOLECULE IS SYMMETRICAL

•Both heavy chairs are identical•Both light chairs are identical

Would quickly fall apart because it is only loosly connected by disulfide bonds.

CAN BE

•Bound to B cells as receptor

•Secreted into plasma, like “freelancers”

IMMUNOGLOBULINE CLASSES

IgG

IgM

IgEIgD

IgA

MNEMONIC RULE

TOTAL AMOUNT OF IMMUNOGLOBULIN

IgG75.602%

IgA15.120%

IgM9.072%

IgD0.202%

IgE0.004%

In serum

IgG H2L2(FORMLE)

•IgG1 – 65%IgG2IgG3IgG4/according to H chain and S-bond location

CHARACTERISTIC OF IgG

• Most abundant• Predominant in secondary response• Can cross the placenta• Opsonizes (enhance phagocytosis)• Transfer

IgA 2*(H2L2)+J+s.c.

J – means Joining chair, what is needed for connecting of 2 Fc – fragments+ secretory component

MAIN IMMUNOGLOBULIN IN SECRETIONS IgA

•Saliva•Tears•Respiratory•Intestinal•Genital

IgA

Secretory component is a polypeptide synthesized by epithelial cells that provide for IgA passage to the mucosal Surface>

Prevent attachment

IgM 5*H2L2+J

• Earlier produced in primary response• Pentamer• Agglutination(most efficient)• Highest avidity• First component of compliment

10 BINDING SITES

HAS NO KNOWN A.B. FUNCTION

IgE

• Medicates immediate hypersensitivity > anaphylactic reaction• Defense against parasites• Does not fix compliment

Property IgG IgA IgM IgD IgE

Serum[mg/dL]

1000

200 120 3 0,05

Sedimention coefficient 7S 7S/11S 19S 7S 8S

MW(*1000) 150 170-400 900 180 190

Struture -mer Mono- Mono-/di- Mono-/penta-

Mono- Mono-

H chain symbol γ α μ δ ΕCompliment ficsation + - + - -Transplacental passage + - - ? -Mediation of allergic reaction

- - - - +

Found in secretions - + - - -Opsonization + - - - -Antigen receptors of B cells

- - + ? -

Polemeric form contain J-chains

- + + - -

ISOTYPES

• Greek: Isos – equal

”We are different, but we are same”

Amino acidic differences in constant regions of antibodies, according to it we have:IgG(1-4)/IgA(1-2)/IgM/IgD/IgEAll people have it, but each of antigen has own specific structure and functions, same for all humans.

ALLOTYPE

• Greek: Allos – other

“ We are same, but we are different “

Antigenic features of antibodies that vary among individuals. Different alleles = different L and H chains.

𝞬 H chain contein an allotype called Gm(gamma) which can differ to one- or two-amino-acids.k L chains are called Inv(individual, patients name)

IDIOTYPES

• Greek: Idios – own

“We are same, but our difference inside of us”

Antigenic determinants formed by the specific amino acids in the hyper variable regions.+ Secondary response against cross-reacting agents-Autoimmune diseasesallergy, anaphylaxis, asthma, transfusion reactions, rheumatoid arthritis, and type I diabetes.

HUMORAL IMMUNITY

Humoral means antibody- mediated immunity. Directed against:• Toxin-induced diseases• Infections (virulence due to polysaccharide capsule)• Certain viral infections

• Systemic• Involves B and T lymphocytes• Specific• Has memory

CLASSIFICATION

THE PRIMARY RESPONSE

• First contact with antigen• Long lag period (7-10 days)• First antibodies are IgM 7 day• Constant increase of antibody concentration• Followed antibodies IgG/IgA production• Elimination of alien• Decrease of antibody concentration (35 day)• !Keeping of some memory cells!

THE SECONDARY RESPONSE

• Contact of B- memory cells with same or  cross-reacting alient• Rapid antibody response( lag period 3-5 days)• Totally higher increase of antibodies amount• Longer period of decreasing of antibodies concentration (of IgG)

DIFFERENCES IN CONCENTATION

MULTIPLE ANTIGENS

• When two or ore antigens are presented at the same time, organism produces antibodies to each of them.

Therefor it is possible to use complex vaccines and immunization got possible.

• DPT(diphtheria, pertussis, tetanus)• MMR(measles, mumps, rubella)

FUNCTION OF ANTIBODIES

•Protection against inflectional Agents •Protection against agent products•Neutralization of toxins•Neutralization of viruses•Opsonize microorganisms*

*making of foreign cell more susceptible(available) for phagocytosis

FUNCTIONS (MNEMONIC RULE)

THANK YOU FOR ATTENTION

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