Monoclonal Antibodies (mAbs)

Definition

• Laboratory-produced proteins that mimic natural antibodies.

• Bind specifically to target antigens (usually on cells or pathogens).

• Used in diagnosis, treatment, and research.

Key Characteristics

1. Specificity

   • Bind to a single epitope on an antigen.

   • Unlike polyclonal antibodies (which bind to multiple epitopes).

   • An epitope is the specific molecular region on the surface of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. It is the precise site where an antibody binds, and it is capable of eliciting an immune response.

2. Monoclonality

   • All antibodies are identical and derived from one B-cell clone.

3. Laboratory Production

   • Produced via hybridoma technology.

   • Fusion of a B-lymphocyte with a myeloma (tumor) cell forms a hybridoma that secretes the desired antibody indefinitely.

Production Process

1. Immunization of a mouse → B cells collected

2. B cells fused with myeloma cells → Hybridomas

3. Screening of hybridomas → Only desired antibody-producing clone selected

4. Clone expanded → Mass production of monoclonal antibodies

           

Applications

1. Disease Diagnosis

• Immunoassays (e.g., ELISA, lateral flow tests)

• Pregnancy and ovulation test kits

• Tissue and blood typing in organ transplantation

2. Disease Treatment

• Cancer: Target tumor cells (e.g., CD markers)

• Autoimmune diseases: Suppress inflammatory molecules (e.g., TNF-alpha)

• Infectious diseases: Block virus entry or promote viral clearance

3. Research

• Cell and molecular identification

• Development of new therapeutic targets

• Protein tagging and molecular interaction studies

Mechanism of Action

• Bind to specific antigen on a cell/pathogen surface

• Trigger immune responses:

  • Antibody-Dependent Cellular Cytotoxicity (ADCC)

  • Complement activation

  • Block receptors or neutralize molecules

Examples of mAbs in Therapy

• High specificity → fewer side effects

• Can be tailored to specific diseases

• Used in personalized medicine

Challenges

• High cost of production

• Risk of immune reactions (e.g., cytokine release syndrome)

• Not orally active – usually given via injection

Monoclonal antibodies represent a revolution in targeted therapy, enabling precision medicine in oncology, immunology, and infectious disease management. Their continued development and affordability are central to future healthcare strategies.