Recombinant human antibodies to IFN-α from the immune repertoires of MG/thymoma donors (83.13)

Abstract

A serum titer of autoantibodies to IFN-α has been reported in several autoimmune conditions and in many cases has been shown to neutralize IFN-α. The IFN-α antibody repertoire from 10 patients with autoimmune myasthenia gravis and associated thymoma (MG/T) was characterized. Surface IgG positive memory B-cells from peripheral blood mononuclear cells (PBMC) were cultured in 384-well plates to produce assayable quantities of antibody. Sensitive antibody microarray and AlphaScreen™ binding assays were used to identify antibodies reactive with IFN-α(2a). A range of IFN-α subtype specificity profiles was observed in competition assays for binding to the 12 subtypes of IFN-α. A subset of these antibodies was expressed recombinantly after recovery of heavy and light chain variable regions by RT-PCR and these recombinant antibodies recapitulated the activities demonstrated in the B-cell culture supernatants. These antibodies fell into 2 groups, blocking binding of IFN-α(2a) to either the IFNAR2 or IFNAR1 subunit of the Type 1 interferon receptor. The ability of these antibodies to neutralize the activity of IFN-α(2a) in a Daudi cell proliferation assay was confirmed. The antibody repertoires of MG/T patients include high affinity antibodies with both broad and narrow specificities for the different subtypes of IFN-α. These function-blocking human antibodies may have therapeutic utility in IFN-α dependent diseases such as SLE.