MONOCLONAL AND POLYCLONAL ANTIBODIES

by - Pinky Varshney

Lucknow University

Antibodies are globular proteins or Immunoglobulins synthesized by a type of white blood cell called plasma cells against the antigen that stimulated its production.

The region of antibody that interact with antigen is called Paratope.

Antigen antibody interaction is specific.

ANTIBODIES

ANTIBODIES

Structure of Antibody

Antigen antibody interaction is specific

An Antigen is any foreign molecule that interact with cells of immune system and could elicit immune response

A pathogen has many epitopes and can elicit many B cells to antibody producing plasma cells thus serum contain antibodies from many clones of cells

Epitopes are regions on antigens that interact with antibody.

Thus serum has antibodies which are polyclonal and monoclonal in nature.

Antigens

Monoclonal antibodies are the antibodies which arise from single clone of cells.

They are homogenous . These are formed against same epitopes of an antigen. These are highly specific.

Polyclonal antibodies are the antibodies which arise from different clone of cells

These are formed against same antigens but different epitopes.

Monoclonal and polyclonal antibodies

Discovery of monoclonal antibodiesThe idea of ‘magic bullet’ was first proposed by Paul Ehrlich who at beginning of 20th century postulated that “if a compound could be made that selective targeted a disease causing organism than a toxin for that organism could be delivered along with agent of selectivity”.

Is by Hybridoma technology Production of monoclonal antibodies is by hybridoma cell

production.

These are typically made by fusing myeloma cells with spleen

cells from a mouse that has been immunised with desired antigen.

A special medium termed HAT medium is used in the process for selection of hybridoma cells.

Monoclonal antibody production

Hypoxanthine, aminopterin , thymidine medium

(HAT) is a selection medium for mammalian cell

culture which relies on combination of aminopterin –

a drug that acts as powerful folate mechanism.

HAT medium

Georges Kohler , Cesar Milstein , Neils karl jerne shared nobel prize for physiology or medicine in 1984 for discovery of Hybridoma technology

Purification of monoclonal antibodies and polyclonal antibodies.

Diagnostic applications Detects protein of interest by immunofloroscence or blotting.

Cardiovascular diseases

Deep vein thrombosis

Location of primary and secondary metastatic tumors

Immunosuppressive therapy. Threauptic applications

Radioisotopes immunoconjugates

Toxin and drug immunoconjugates

Immunoliposome based kits

In cancer

Applications of monoclonal antibodies

Sandwich ELISA for tumor markers or other antigens can be designed with polyclonal antibodies

Polyclonal antibodies are useful in histopathological analysis using immunoperoxides staining technique.

In some cases of affinity purification of antigens, polyclonals have advantages over MAbs.

Applications of polyclonal antibodies

Monoclonal antibodies Unlimited supply

High specificity

Polyclonal antibodies High affinity

Wide choice of species

Less then 5% of immunoglobulins fraction will be wanted antibodies

Advantages