Antibodies That React with Bovine T Lymphocytes Expressing the T Cell Receptor Β Chain Subgroup BV20 Inhibit Antigen Recognition

In recent years, molecular studies have provided detailed information on the bovine T cell receptor (TCR) variable gene repertoire, both in resting T cells and during T cell responses. However, studies of the biological function of the receptor have been hampered by a lack of reagents that recognise the protein. Herein, we describe the characterisation of two antibodies (IL-A47 and IL-A98) that recognise T cells expressing the TCR VB20 subfamily of BV genes. These antibodies each recognise a small subset of αβ T cells in PBMC, including subsets of both CD4 and CD8 T cells. One of the antibodies (IL-A98) recognises a smaller subset of cells within the IL-A47+ population. When tested on a panel of T cell clones expressing different αβ TCR subfamilies of β chain genes, IL-A47 was found to react only with clones expressing the BV20 subfamily, which in cattle has undergone expansion due to gene duplication; IL-A98 reacted with a subset of the BV20 subfamily members. IL-A47 was shown to profoundly inhibit recognition of target cells by cytotoxic T cell clones, an effect that was mediated via the effector T cell rather than the target cells.