Treatment of mouse thymus cells with phosphatidylinositol-specific phospholipase C preferentially abrogates their reactivity with autoantibodies to the Thy-1 antigen

Thy-1 molecules have been shown to become anchored to the membrane of thymocytes and of T-cells via a phosphatidylinositol link. In the present study the intensity of immunofluorescent staining of mouse thymus cells by monoclonal xenoantibodies and alloantibodies specific for the Thy-1.2 determinant was significantly reduced following exposure of the cells to phosphatidylinositol-specific phospholipase C (PI-PLC). The majority of the PI-PLC-treated thymus cells retained, however, some reactivity with Thy-1.2 antibodies. In contrast, the immunofluorescent staining of thymus cells with monoclonal autoantibodies to Thy-1 determinants (20-10-5 and C16-31) was completely abolished by PI-PLC treatment. These results suggest that whereas monoclonal autoantibodies to Thy-1 react preferentially with PI-PLC-sensitive Thy-1 molecules, monoclonal antibodies to the Thy-1.2 specificity react with all cell surface Thy-1 molecules, regardless of their sensitivity to PI-PLC treatment.