Inhibition of E-rosette formation and phagocytosis by human blood leucocytes after treatment with the dengue virus-induced cytotoxic factor.

We have observed earlier that T lymphocytes of dengue type 2 virus (DV)-infected mouse spleen produce a cytotoxic factor (CF) which kills T lymphocytes and macrophages of the spleen of normal mice or animals of other species. In the present study an effort was made to study the effect of CF treatment on human peripheral blood leucocytes. After treatment with various dilutions of CF at 4 degrees for 1 hr 25%-36% of T lymphocytes lost their capacity to form E rosettes and 25%-36% of monocytes lost their phagocytic function. Cytotoxic-factor treatment had no effect on formation of EAC rosettes by B lymphocytes and the phagocytic functions of polymorphonuclear cells. Pretreatment of cells with 2,4 dinitrophenol, reduced glutathione or ouabain, which act on the cell membrane, inhibited the effect of CF on E-rosette formation and phagocytosis. This indicated that CF acts by inducing changes in the cell membrane. It is likely that production of a similar factor in DV-infected humans is responsible for similar alterations observed in their blood.