Interferon exerts a cytotoxic effect on primary @entity1 XXXX cells.

@entity1 @entity5 @entity665 @entity1582 @entity3027
A dye exclusion method was used for testing the sensitivity of primary @entity1 @entity1582 and normal bone-marrow cells to interferon ( @entity3027 ). Following 4 days of incubation with 5000 units/ml of natural (n) @entity3027 , there was a greater than 90% decrease in the number of viable @entity1582 cells in cultures from some @entity1 , whereas @entity1582 cells from other @entity1 showed intermediate or no sensitivity to @entity3027 . The number of viable non-malignant bone-marrow cells (from the same @entity1 ) following a 4-day exposure to nIFN-alpha (5000 units/ml) decreased by 10-60%. Exposure of malignant and non-malignant bone-marrow cells to natural beta- and recombinant alpha- and gamma- @entity3027 , also induced a decrease in the number of viable cells. The decreased number of viable @entity1582 cells could be observed already after 1 day of exposure to @entity3027 in vitro. To test whether inhibition of proliferation could account for the observed effects, proliferation, as measured by @entity665 uptake, was studied in some experiments. Only approx. 1-2% of the @entity1582 cells were labeled with @entity665 during the 4 days of culture in vitro, whereas the proportion of labeled non-malignant cells was approx. 40%. Thus, the @entity3027 -induced reduction of cell number in normal bone-marrow cells could possibly be attributed to a cell multiplication inhibitory effect of @entity3027 , whereas the effect observed in @entity1582 cells cannot be attributed to cell multiplication inhibition. To test the possibility that the reduction in the number of @entity1582 cells could be attributed to the activity of autologous cytotoxic T-cells, NK-cells or macrophages, these cells were depleted in some experiments. Depletion of these cells did not, however, influence the @entity3027 -induced decrease in the number of viable @entity1582 cells. We thus conclude that @entity3027 can reduce the number of viable @entity5 cells by a cytotoxic effect, unrelated to cell multiplication inhibition.
