[Natural cytotoxic activity of mouse bone marrow and spleen cells during regeneration after exposure to cyclophosphamide].

The time course of the activity of natural killers in the bone marrow and spleen of mice was examined after exposure to cyclophosphamide. The activity of natural killers abruptly dropped one day after the cyclophosphamide injection. In the bone marrow, it was not detectable from the 2nd till the 6th day. The minimal cytotoxicity in the spleen was recorded between the 3rd and 6th day. Following 7 days there was a rapid recovery of natural cytotoxic activity in both organs.