Involvement of carbohydrate moieties in the expression of effector activity of cytotoxic T cells against syngeneic tumor cells.

Cytotoxic T lymphocytes (CTL) were raised against syngeneic plasmacytoma MOPC-315 cells by culturing spleen cells immunized with MOPC-315 cells 7 to 14 days previously, in the presence of MOPC-315 cells for 5 days. The cytotoxic activity of these CTL was blocked by D-mannose, indicating that mannose-containing carbohydrate moieties are involved in the expression of cytotoxic activity. Investigations were performed to determine which cells, effector or target, possess carbohydrate moieties, by employing procedures by which a part or most of the carbohydrate on cells can be removed. When target cells were treated with 2-deoxy-D-glucose, tunicamycin or trypsin, the levels of cytotoxic activity of the CTL were reduced. However, the reduced activities were still blocked by adding D-mannose at the effector phase. Treatment with alpha-mannosidase did not affect the level of cytotoxicity or mannose-sensitivity. In contrast, when effector cells were treated with tunicamycin by adding it to the culture one day before harvest, the level of cytotoxic activity was reduced, but the cytotoxic activity was no longer blocked by D-mannose. A similar result was obtained when effector cells were treated with periodate after 5 days of culture. However, the treatment of effector cells with alpha-mannosidase did not affect the cytotoxicity of the CTL. Thus, it was shown that effector cells possess mannose-containing carbohydrate moieties which are involved in the full expression of CTL to syngeneic MOPC-315 cells.