Lymphocytes from healthy subjects and patients with chronic lymphocytic leukemia were exposed to graded hypotonic salt solutions and to distilled water. Nucleoproteins released into the media from 5x106 cells were measured spectrophotometrically at 260 mµ as an estimate of cell fragility.
Leukemic lymphocytes were relatively more resistant to hypotonic stress than normal cells. Cell volume and extractable nucleoproteins were shown to be the same for both groups of cells. While nucleoproteins released from the healthy cells underwent a greater optical density increase in distilled water than anticipated, the leukemic cell products exhibited no significant color change in distilled water environment for periods up to 3 hours.