Questions and Answers
What is the main mechanism of transport for molecules like mAb within a fluid?
What is the difference between phagocytosis and pinocytosis?
How do mAb preferentially bind to antigens?
How are mAb eliminated from the body?
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Which type of mAb is degraded the fastest?
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What determines the binding of mAb to antigens?
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What is the role of the Fc receptor in mAb?
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What is the consequence of high competition between mAb and the endogenous antigen ligand?
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What is the difference in the degradation rate between human and murine mAb?
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What is the key factor in the binding of mAb to antigens?
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Study Notes
Complement-Dependent Cytotoxicity and Antibody Functions
- Complement-dependent cytotoxicity (CDC) involves recognition of the Fc portion of antibodies, independent of specific antigen recognition.
- Antibodies neutralize exotoxins and viruses by targeting specific structures on microorganisms.
- Preventing bacterial adherence to host cells is a crucial antibody function.
- The membrane attack complex (MAC) leads to cytolysis, facilitating cell destruction.
- Agglutination is a process by which antibodies clump microorganisms together, enhancing their clearance.
- Immobilization of bacteria and protozoa occurs through specific antibody binding.
- Opsonization enhances phagocytosis by marking pathogens for destruction.
Strategies for Targeting Tumor Cells
- Naked antibodies can target tumor cells or be combined with radioactive ligands via streptavidin or bispecific antibodies.
- Bispecific antibodies can simultaneously bind tumor cells and immune cells, enhancing the immune response.
- Simple chain variable fragments (scFvs) can be linked to liposomes that deliver drugs or enzymes for localized treatment.
- Antibody-directed enzyme prodrug therapy (ADEPT) utilizes enzymes to convert prodrugs into active chemotherapeutics at tumor sites.
- Potelligent technology enhances antibody efficacy by removing fucose, increasing binding affinity to FcγRIIIa (CD16), leading to improved antibody-dependent cellular cytotoxicity (ADCC).
Clinical Implications and Efficacy
- Potelligent-enhanced antibodies are expected to show superior efficacy and safety in human patients.
- Increased Fc receptor binding improves clinical responses and reduces the necessary therapeutic doses.
- Antibody therapies are typically employed when the patient's immune system is intact, targeting cancer or pathogens.
Transport and Binding Mechanisms
- Antibodies travel through fluids, utilizing conventional transport methods and endocytosis (both receptor-mediated and non-receptor-mediated).
- Specific binding occurs via the Fab portion of the antibody, while non-specific binding occurs through the Fc portion.
- Antibodies favor binding to soluble antigens; competition exists when antigens are accessible in both soluble and cell-surface forms.
Antibody Elimination and Stability
- Antibodies face degradation through proteolysis, with Fc receptors providing protection against rapid catabolism, ensuring longer half-lives.
- The stability of monoclonal antibodies (mAbs) varies: murine mAbs degrade quickly, while humanized mAbs have a longer lifespan (murine < chimeric < humanized < human).
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Description
This quiz covers the various functions of antibodies, including complement-dependent cytotoxicity, neutralization of exotoxins and viruses, prevention of bacterial adherence to host cells, and membrane attack complex formation.
