Tissue distribution of the T cell activation antigen Ta1. Serological, immunohistochemical and biochemical investigations.

The recently described Ta1 antigen is expressed by activated T cells in vitro and in vivo, as observed in patients with certain immune-mediated diseases, such as multiple sclerosis. In this paper we report on the tissue distribution of the Ta1 antigen. Serological testing of human tumour cell lines and immunohistochemical analysis of human tissue sections revealed a reactivity of the anti-Ta1 antibody with normal and malignant tissues of the upper gastro-intestinal tract, the biliary tract, exocrine pancreas and kidney. SDS-PAGE analysis of immunoprecipitates from 125I-labelled cells, employing the anti-Ta1 antibody, yielded a 113-115 kD band from three serologically Ta1 positive tumour cell lines, from a serologically Ta1 negative human EBV-transformed B lymphoblastoid cell line, from peripheral blood mononuclear cells (PBMC) and, as previously described, a 105 kD band from PHA activated T cells (Fox et al., 1984). After endoglycosidase F treatment similar bands of 85 kD were precipitated from activated T cells and from tumour cell lines. It is therefore likely that very similar glycoproteins, which differ only modestly in the size of carbohydrate chains, bear the Ta1 epitope on Ta1 positive tissues.