The antigen-specific, major histocompatibility complex-restricted receptor on T cells. VI. An antibody to a receptor allotype.

Abstract

A monoclonal antibody, KJ16-133, was prepared from the cells of a rat immunized with the purified receptor for antigen plus I-A of a BALB/c T cell hybridoma, DO-11.10. Unlike most other monoclonal anti-receptor antibodies that were described before, KJ16-133 is not clone specific. It reacts with .apprx. 20.degree. of the receptors on T cells of normal BALB/c mice. It also reacts with about the same percentage of antigen-specific, major histocompatibility complex (MHC)-restricted or allogeneic I-region specific T cell hybridomas. Reaction of KJ16-133 with a given T cell hybridoma does not seem to depend on the antigen specificity or MHC-restricting element of the T cell in question. The determinant recognized by KJ16-133 has some unexpected properties. It is absent in several strains of mice including SJL/J and SJA/20, but present on the T cells of most other commonly used strains. The determinant recognized therefore does not map to Igh. A clone-specific antiidiotypic antibody and KJ16-133 probably recognize determinants on different parts of the receptor. The binding of a clone-specific antibody to target T cells is relatively temperature insensitive, whereas KJ16-133 binds well to cells at 37.degree. C but poorly to cells at 4.degree. C. The determinant recognized by a clone-specific antibody is sensitive to reduction and alkylation of the receptor, whereas KJ16-133 reactivity is not. Binding of KJ16-133 at saturation concentrations to target T cells does not block the binding of a clone-specific antibody. Binding of a clone-specific antibody only marginally inhibits binding of KJ16-133. KJ16-133 is apparently directed against an allelic determinant on T cells that may be close to the membrane, and not in the receptor binding site for antigen plus MHC. The antibody may recognize an allele of a constant region isotype, or an allele of a J region.