Epitope mapping of human Fas using peptide phage display

Area of Science:

• Immunology
• Biochemistry
• Molecular Biology

Background:

• Soluble Fas plays a critical role in apoptosis and immune regulation.
• Accurate measurement of soluble Fas isoforms is essential for understanding disease mechanisms.
• Existing methods may lack the sensitivity or specificity for detecting diverse soluble Fas variants.

Purpose of the Study:

• To develop a sensitive sandwich enzyme immunoassay (EIA) for quantifying soluble Fas in human serum.
• To identify and characterize specific isoforms of soluble Fas detectable by the developed assay.
• To determine the epitope binding sites of monoclonal antibodies used in the assay.

Main Methods:

• Development of a sandwich EIA utilizing SA-7 and SA-8 monoclonal antibodies against full-length human Fas.
• Determination of assay sensitivity, with a threshold of 0.3 ng/ml.
• Epitope mapping of SA-7 and SA-8 antibodies using a peptide phage library to identify binding residues (SA-7: 129-134 (CKPNFF); SA-8: 94-99 (KAHFSS)).

Main Results:

• Successful development of a sensitive sandwich EIA for soluble Fas detection.
• Identification of several soluble Fas isoforms, including FasExo6Del, FasExo4Del, FasExo4,6Del, FasExo4.7Del, and FasExo8Del.
• Precise localization of antibody epitopes, confirming specific binding interactions.

Conclusions:

• The developed sandwich EIA provides a reliable method for detecting specific soluble Fas isoforms in human serum.
• The characterized antibody epitopes enhance the understanding of Fas-ligand interactions.
• This assay has potential applications in diagnosing and monitoring conditions associated with altered Fas levels.