Epitope complementarity and idiotypic interactions: A study of idiotypic-like interactions between anti-cytidine and anti-guanosine A/J mouse monoclonal antibodies—I. Characterization of these interactions

Abstract

Idiotypic-like interactions between mAbs directed against cytidine (Cyd) or guanosine (Guo) nucleosides were characterized. These mAbs, Cyd-1 (IgG2b, κ), Guo-1 (IgG1, κ) and Guo-2 (IgG1, κ) were derived from splenocytes of A/J mice immunized with Cyd-KLH or Guo-KLH and recognized the nucleoside base moieties involved in hydrogen bonding. The interactions between Guo-1 or Guo-2 and Cyd-1 involved cross-reactive or distinct-but-neighboring paratope-associated idiotopes. These interactions were characterized by K d values of 4.6 × 10 −6 and 1.8 × 10 −6M, respectively. The three anti-nucleoside mAbs exhibited Ab2β properties and manifested epibody (Ab2ϵ) activity towards ssDNA. We compared these idiotypic-like reactivities with the anti-idiotypic activity of an intentionally induced IgGi, κ anti-idiotype mAb prepared with splenocytes from A/J mice immunized with Cyd-1. This Ab2 antibody which bound to Cyd-1 with a K d of 1.1 × 10 −9 M, manifested an Ab2γ activity, i.e. it recognized a paratope-associated idiotope on Cyd-1 without exhibiting Ab2β properties. In addition, the anti-(Cyd-1) completely inhibited (Cyd-1)-(Guo-1) and (Cyd-1)-(Guo-2) interactions.