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Binding parameters of monoclonal antibodies reacting with ovarian carcinoma ascites cells
M J Mattes1, K O Lloyd, J L Lewis
1Center for Molecular Medicine and Immunology, Newark, NJ 07103.
Abstract:
Binding parameters were determined for four mouse monoclonal antibodies reacting with three antigens on the surface of fresh human ovarian carcinoma ascites cells, under nearly physiological conditions. The object of these experiments was to aid in the selection of the optimal monoclonal antibodies for intraperitoneal immunotherapy. The number of antigenic sites per cell, the effective equilibrium association constant (affinity) and the half-life for dissociation were: for Ab MH99, 1.2 x 10(6) sites/cell, (1.9-4.1) x 10(8) M-1, and 4 h; for Ab MX35, (3.2-4.1) x 10(5) sites/cell, (3.4-4.8) x 10(8) M-1, and greater than 10 h; and for Ab MW207, 1.3 x 10(5) sites/cell, (3.6-4.1) x 10(9) M-1, and 3.1 h, respectively. One of the antigens, MH99, is recognized by five different monoclonal antibodies, and competitive inhibition experiments demonstrated that two distinct determinants are present; this antigen is also recognized by the previously described Ab 17-1A. These binding data will aid the rational design of immunotherapy strategies.
Insights
Researchers characterized monoclonal antibodies for ovarian cancer immunotherapy. Antibody MX35 demonstrated high affinity and long half-life, suggesting its potential for effective intraperitoneal treatment strategies.
Area of Science:
- Immunology
- Oncology
- Biochemistry
Background:
- Monoclonal antibodies (mAbs) are crucial for targeted cancer therapies.
- Optimizing mAb selection requires understanding their binding kinetics to tumor antigens.
- Ovarian carcinoma presents a significant challenge, necessitating improved immunotherapeutic approaches.
Purpose of the Study:
- To determine binding parameters of mouse monoclonal antibodies against human ovarian carcinoma ascites cells.
- To identify optimal monoclonal antibodies for intraperitoneal immunotherapy based on binding characteristics.
- To characterize antigenic sites and antibody interactions for rational immunotherapy design.
Main Methods:
- Measurement of binding parameters including antigenic sites per cell, effective equilibrium association constant (affinity), and dissociation half-life.
- Utilized nearly physiological conditions for accurate assessment of antibody-antigen interactions.
- Employed competitive inhibition experiments to identify distinct antigenic determinants.
Main Results:
- Quantified antigenic sites, affinity, and half-life for antibodies MH99, MX35, and MW207.
- Antibody MX35 exhibited high affinity (3.4-4.8 x 10^8 M^-1) and a half-life >10 hours.
- Identified two distinct determinants on the MH99 antigen, recognized by multiple antibodies including 17-1A.
Conclusions:
- Binding data provide a foundation for selecting optimal monoclonal antibodies for ovarian cancer immunotherapy.
- Antibody MX35 shows promising characteristics for effective intraperitoneal delivery and sustained target engagement.
- Understanding antigen heterogeneity is key for developing robust and rational immunotherapy strategies.