Specificity of the Ninth Workshop Anti Ia Alloantisera as Assessed by the Direct Binding Assay

Abstract

Antibody specificity can be easily defined when the binding of antibody to antigen is measured directly. A sensitive determination of such direct binding is possible by the use of radiolabeled antigen. This is also the case for alloantigens [1, 2]. We have been using ¹²⁵I-labeled la antigens for specificity assay of the alloantisera and more recently of the monoconal antibodies. The assay method (we call it the direct binding assay) first allows reaction of a test alloantiserum or a monoclonal antibody with a radioiodinated la preparation, and then measures the extent of binding by the double-antibody technique [2]. When a panel of ¹²⁵I-labeled la preparations of different specificities is used, the major or putative antibody specificity can be deduced from the reaction pattern. This assay has been found particularly useful in the search for antibodies that can be used for la typing by the binding inhibition assay [2, 3] and also for immunospecific isolation of la molecules carrying different specificities [4].

This work was supported in part by USPHS-grants AI20251 and CA17276, awarded by the National Institute of Allergy and Infectious Diseases and the National Cancer Institute, Department of Health and Human Services, and by a grant from Progetto Finalizzato CNR Ingegneria Genetica Sottoprogetto “Basi moleculari delle malattie ereditarie”, CNR grants 820130504 and 820133696, and a grant awarded by the North Atlantic Treaty Organization