| Abstract: | Attempts to block specific T cell recognition with soluble extracts have been uniformly unsuccessful. However, we found that glycopeptides prepared from three MHC-different tumor cell lines were able to inhibit binding of allospecific cytotoxic T lymphocytes (CTL) to an appropriate tumor cell or Con A blast target cell. Inhibition was only observed when the MHC of the cell providing the glycopeptide was the same as the MHC of the target cell being recognized. This result was obtained by using both fully allogeneic CTL and CTL generated between B10 congenic mice differing only at the MHC. This suggests that the inhibition depends on the MHC expressed by the target cell. Because we extensively pronase digested cell glycoproteins and then enriched for glycopeptides containing small amounts of peptide, we attribute the inhibition to the carbohydrate portion of the glycopeptide. Our observations suggest that CTL may, in part, recognize carbohydrate molecules on the target cell surface whose specific structure(s) is influenced or regulated by genes in or near the MHC. They also suggest that the T cell receptor complex has some lectin-like properties. |
