Microspectrophotometric Estimation of the Desoxyribonucleic Acid (DNA) Content of Individual Normal and Leukemic Human Lymphocytes

The DNA content, in arbitrary units, of individual circulating lymphocytes from nine normal subjects, nine patients with chronic lymphocytic leukemia, and five patients with acute lymphocytic leukemia was estimated microspectrophotometrically with the Feulgen dye. Normal circulating lymphocytes were found to contain twice the average DNA content of normal human spermatids, corroborating their diploid chromosome number. Lymphocytes from normal and leukemic lymph node and bone marrow were frequently found possessing four times the average spermatid DNA value. Three out of nine patients with chronic lymphocytic leukemia, and four of five patients with acute lymphocytic leukemia had significantly increased numbers of circulating lymphocytes containing DNA values which were elevated above the normal diploid value. The patients demonstrating cells with elevated DNA values were in a clinically exacerbated phase of their disease. The significance of these findings is discussed.