-Jasmine Kaur

An antibody is a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target.

Monoclonal antibodies (mAb) are antibodies that are identical because they were produced by one type of immune cell, all clones of a single parent cell.

Polyclonal antibodies are antibodies that are derived from different cell lines.

ANTIBODIESANTIBODIES

Derived from Derived from different B different B

Lymphocytes cell Lymphocytes cell lineslines

POLYCLONAL.POLYCLONAL. MONOCLONAL.MONOCLONAL.

Derived from a single Derived from a single B cell cloneB cell clone

Batch to Batch Batch to Batch variation affecting variation affecting

Ab reactivity & titreAb reactivity & titre

mAb offer mAb offer Reproducible, Reproducible, Predictable & Predictable &

Potentially Potentially inexhaustible supply inexhaustible supply of Ab with exquisite of Ab with exquisite

specificityspecificityEnable the Enable the

development of development of secure immunoassay secure immunoassay

systems.systems.

NOT Powerful tools NOT Powerful tools for clinical diagnostic for clinical diagnostic

teststests

The application of monoclonal antibodies can be broadly categorized as:

a) Diagnostic application b) Therapeutic application c) Catalytic MAb (Abzymes)

MAbs are utilized in diagnostic kits for the diagnosis of various infectious diseases, detecting pregnancy, monitoring drug levels, matching histocompatibility antigen, detecting diabetes, cancer and in immunoscintigraphy.

 FDA licensed a new diagnostic imaging agent that can determine the extent of disease in patients diagnosed with small cell lung cancer (SCLC). Because these agents can detect tumor in different part of the body at one time, it can help physician to advice certain patients with advanced forms of the disease about treatment option without requiring further diagnostic tests.   

      The new agent, Nofetumomab, is a fragment of a

monoclonal antibody that when tagged with the radioisotope technique, can detect a protein found on the surface of most small lung cancer cells.

Improving the out come of bone marrow transplantation by using CD52 MAbs to prevent Graft-Versus-Host disease and Graft rejection. Graft-versus-Host Disease (GVHD) is a major cause of mortality and mobidity after allogenic bone marrow transplantation, but can be avoided by removing T-lymphocytes from the donor bone marrow.

However, T-cell depletion increases the risk of graft rejection. This study examined the use of CD52 MAb to eliminate   T- cells from both donor marrow and recipient to prevent both GVHD and rejection.

Alemtuzumab is the monoclonal antibody used for this purpose.

The antibodies are extremely efficient at binding ground states of the target molecule while enzymes obtained their catalytic efficiency from tight binding of the transition state for the reaction.

Thus antibodies can be made efficient catalysts if they are made for reaction transition state.

Lemer and his co-workers explored the probability of enzyme like action of antibodies by producing hapten-carrier complex where the hapten structurally resembled transition state and anti-hapten MAbs generated, gave catalytic activity.

The hydrolysis of substrate increased thousand fold after incubation.