Neuraminidase treatment enhances allogeneic stimulation of unprimed CD8+ T cells

Abstract

Many cell types are known to stimulate CD8+ T cells in allogeneic recognition such as mixed lymphocyte reaction (MLR). Whereas dendritic cells are most potent among them, T cells are usually considered very poor in stimulating CD8+ T cells although there are some tumor cells that are weakly stimulatory. T cells, as a stimulator, cultured in the presence of concanavalin A that were otherwise nonstimulatory to CD8+ T cells appeared to stimulate CD8+ T cells strongly when they were pretreated with neuraminidase. The enhancement of MLR by neuraminidase could be achieved by treating either the stimulators or responders with neuraminidase. Removal of negatively-charged sialic acid moieties from the cell surface, which reduced electrostatic repulsion between responders and stimulators to give better cell-cell contact might be responsible for the enhanced MLR. In addition, neuraminidase treatment also appeared to deliver activation signal to responding T cells since it could activate CD8+ T cells in synergy with phorbol myristate acetate. The maximal responses were observed when both responders and stimulators were treated with neuraminidase.