Antibody engineering is the design, modification, and optimization of antibodies to enhance their specificity, affinity, stability, and therapeutic potential. Since the development of monoclonal antibodies in the 1970s, advances in molecular biology and protein engineering have enabled the creation of next-generation antibody formats for diagnostics, therapeutics, and research.

Antibodies (immunoglobulins) are Y-shaped glycoproteins produced by B cells. They consist of:

1. Two heavy chains and two light chains.
2. Variable (V) regions that bind to antigens.
3. Constant (C) regions that mediate immune effector functions.

The antigen-binding fragment (Fab) is responsible for specificity, while the fragment crystallizable (Fc) region interacts with immune system components .

2.1 Humanization

Early therapeutic antibodies were derived from mice, which triggered human anti-mouse antibody (HAMA) responses. Humanization involves grafting murine complementarity-determining regions (CDRs) onto human antibody frameworks to reduce immunogenicity.

2.2 Affinity Maturation

Affinity maturation improves antibody–antigen binding strength using directed evolution, phage display, or error-prone PCR .

2.3 Bispecific Antibodies

Bispecific formats bind two different epitopes or antigens simultaneously. They are valuable in immuno-oncology, enabling T-cell recruitment to tumor cells.

2.4 Antibody Fragments

Single-chain variable fragments (scFv), F(ab')₂, and nanobodies provide smaller, more penetrative formats for diagnostic imaging and targeted therapy.

2.5 Fc Engineering

Altering the Fc domain can modulate antibody half-life, effector function, and immune activation.

1. Phage Display: Uses bacteriophages to present antibody fragments for selection.
2. Yeast Display: Allows eukaryotic folding and glycosylation patterns.
3. Hybridoma Technology: Classical method for monoclonal antibody generation.
4. Transgenic Animals: Produce fully human antibodies (e.g., HuMAb mice).

4.1 Therapeutics

1. Cancer immunotherapy (e.g., trastuzumab, pembrolizumab).
2. Autoimmune disease treatment (e.g., anti-TNF antibodies for rheumatoid arthritis).
3. Infectious disease prevention (e.g., monoclonals for RSV and COVID-19) .

4.2 Diagnostics

1. Lateral flow assays.
2. ELISA and immunohistochemistry.
3. Imaging agents for PET and MRI.

4.3 Research Tools

1. Protein localization studies.
2. Functional blocking experiments.
3. Flow cytometry and cell sorting.

1. Immunogenicity in therapeutic applications.
2. Manufacturing complexity and cost.
3. Intellectual property restrictions limiting certain engineering approaches.

Advances in AI-driven protein design, synthetic biology, and CRISPR-enabled cell line development are accelerating antibody discovery. The emergence of multispecific antibodies, antibody-drug conjugates (ADCs), and CAR-T cell therapies will continue to reshape the therapeutic landscape .

Antibody engineering enables the creation of highly specific and potent tools for diagnostics, therapeutics, and research. As computational design and high-throughput screening evolve, the next generation of antibodies will offer greater precision, reduced side effects, and broader applications in global health.