Neuraminidase treatment of human T lymphocytes: effect on Fc receptor phenotype and function.

Purified peripheral blood T cells or T mu cells from normal healthy donors were treated in vitro with neuraminidase and examined for the expression of IgM Fc and IgG Fc receptors. Increasing concentrations of neuraminidase selectively removed IgM Fc receptors, whereas the number of T cells expressing IgG Fc receptors was significantly increased. Following neuraminidase treatment, IgM Fc receptors could be regenerated by reincubation of T cells at 37 degrees C. The regeneration of IgM Fc receptors could be blocked by treatment with cycloheximide. Neuraminidase treatment of purified T mu cells resulted in the expression of IgG Fc receptors on a subpopulation of T mu lymphocytes. A small percentage of the neuraminidase-treated T cells expressed receptors for both IgG and IgM. Treatment of T cells with neuraminidase did not effect T cell-mediated spontaneous cytotoxicity (SLMC) or antibody-dependent cellular cytotoxicity (ADCC). Our results indicate that T cell Fc receptor phenotypes can be modulated in vitro without significantly altering their functional capacity.