A Public T cell Receptor Recognized by a Monoclonal Antibody Specific for the D‐J Junction of the β‐chain

It is becoming increasingly clear that T cell responses against many antigens are dominated by public α/β T cell receptors ( TCR s) with restricted heterogeneity. Because expression of public TCR s may be related to resistance, or predisposition to diseases, it is relevant to measure their frequencies. Although staining with tetrameric peptide/major histocompatibility complex ( pMHC ) molecules gives information about specificity, it does not give information about the TCR composition of the individual T cells that stain. Moreover, next‐generation sequencing of TCR does not yield information on pairing of α‐ and β‐chains in single T cells. In an effort to overcome these limitations, we have here investigated the possibility of raising a monoclonal antibody ( moA b) that recognizes a public TCR . As a model system, we have used T cells responding to the 91–101 CDR 3 peptide of an I g L ‐chain (λ2 315 ), presented by the MHC class II molecule I‐E d . The CD 4 + T cell responses against this pMHC are dominated by a receptor composed of Vα3Jα1;Vβ6DβJβ1.1. Even the V (D)J junctions are to a large extent shared between T cell clones derived from different BALB /c mice. We here describe a murine moA b ( AB 10) of B 10.D2 origin that recognizes this public TCR , while binding to peripheral T cells is negligible. Binding of the moA b is abrogated by introduction of two G ly residues in the D‐J junction of the CDR 3 of the β‐chain. A model for the public TCR determinant is presented.