ANTIBODY ENGINEERIN

GPrepared by:

Alyssa Mari A. Reyes

ANTIBODIES Also known as immunoglobulins (Ig) Gamma globulin proteins that are

found in blood or other bodily fluids of vertebrates

Used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses.

Typically made of basic structural units- each with two large heavy chains and two small light chains- to form, momomers, dimers, polymers or pentamers

ANTIBODIESProduced by a subset of

lymphocytes called B cells.B cells that are stimulated will

actively secrete antibodies and are called plasma cells

can occur in two physical forms, a soluble form that is secreted from the cell, and a membrane-bound form that is attached to the surface of a B cell and is referred to as the B cell receptor.

ANTIGEN Most are proteins or large

polysaccharides from a foreign organism.Microbes: Capsules, cell walls,

toxins, viral capsids, flagella, etc.Nonmicrobes: Pollen, egg white , red

blood cell surface molecules, serum proteins, and surface molecules from transplanted tissue.

Molecular weight of 10,000 or higher.

ANTIGEN Substance that evokes the production

of one or more antibodies. Each antibody binds to a specific

antigen by way of an interaction similar to the fit between a lock and a key.

The substance may be from the external environment or formed within the body.

The immune system will try to destroy or neutralize any antigen that is recognized as a foreign and potentially harmful invader.

ANTIGEN

Epitope: Small part of an antigen that

interacts with an antibody.Any given antigen may have several

epitopes.Each epitope is recognized by a

different antibody.

ANTIBODIES ARE PROTEINS THAT RECOGNIZE SPECIFIC ANTIGENS

EPITOPES: ANTIGEN REGIONS THAT INTERACT WITH ANTIBODIES

ISOTYPES

CLASS/ISOTYPE SWITCHING Isotype or class switching is a biological process

occurring after activation of the B cell, which allows the cell to produce different classes of antibody (IgA, IgE, or IgG).

Class switching occurs in the heavy chain gene locus by a mechanism called class switch recombination (CSR). This mechanism relies on conserved nucleotide motifs, called ''switch (S) regions'', found in DNA upstream of each constant region gene (except in the δ-chain). 

The DNA strand is broken by the activity of a series of enzymes at two selected S-regions. The variable domain exon is rejoined through a process called non-homologous end joining (NHEJ) to the desired constant region (γ, α or ε). This process results in an immunoglobulin gene that encodes an antibody of a different isotype.

CONSEQUENCES OF ANTIGEN-ANTIBODY BINDINGAntigen-Antibody Complex: Formed when an

antibody binds to an antigen it recognizes.Affinity: A measure of binding strength.1. Agglutination: Antibodies cause antigens

(microbes) to clump together. IgM (decavalent) is more effective that IgG

(bivalent). Hemagglutination: Agglutination of red

blood cells.2. Opsonization: Antigen (microbe) is

covered with antibodies that enhances its ingestion and lysis by phagocytic cells.

3. Neutralization: IgG inactivates viruses by binding to their surface and neutralize toxins by blocking their active sites.

AGGLUTINATION

NEUTRALIZATION/OPZONISATION

ANTIBODY FUNCTIONContribute to humoral immune system:1. Prevent pathogens from entering or

damaging cells by binding to them2. Stimulate removal of pathogens by

macrophages and other cells by coating the pathogen

3. Trigger destruction of pathogens by stimulating other immune responses such as the complement pathway.