Identification of myelin-associated glycoprotein (MAG) on the cell surface of mononuclear cells in human peripheral blood by a heterologous antiserum.

Although cross-reactivity between T cells and nervous tissue elements has been reported previously, the antigenic determinants of the cross-reactivity are still unknown. In this study, using immunofluorescence, we demonstrate that the same antigenic determinant as myelin-associated glycoprotein (MAG) exists on the cell surface of mononuclear cells in human peripheral blood. MAG positive cells of thirteen healthy individuals were from 6.1 percent to 14.0 percent (mean +/- standard deviation: 9.1 +/- 2.0% of total mononuclear cells in human peripheral blood). The percentage of MAG positive cells was diminished from 9.3% to 1.3% by preincubation with Leu-7, a monoclonal antibody against human natural killer cells. The percentage of Leu-7 positive cells was not changed by preincubation with anti-MAG antiserum. MAG may be one of the specific antigens which exist in both human peripheral blood mononuclear cells and nervous tissues, and may also be a marker of human natural killer cells.