Senescent Changes in the Content and the Metabolism of Nucleic Acids and Protein in Human Peripheral Blood Lymphocytes

Abstract

Authors have found that the content of nucleic acids and protein in human peripheral blood lymphocytes correlate well with the subjects age.
Forty-two persons (20 males, 22 females, aged 4-77) were utilized as a control. 8 persons with acute inflammatory diseases and a case of Werner's syndrome were also analized.
Lymphocytes were incubated with ¹⁴C-leucine and ²P-orthophosphate and then nucleic acids and protein were estimated both colorimetrically and radiologically.
Mean lymphocyte DNA content was 7.00±0.19μg. per million cells, and this value was extremely constant for all subjects. Thus the ratio of RNA/DNA and the ratio of protein/DNA was taken as a reliable index of changes in RNA and protein content of the lymphocytes.
The ratio of RNA/DNA and the ratio of protein/DNA declined until the mid-twenties, and then rose steadily with age. A 44-year old pateints with Werner's syndrome had these ratios of a control nearly 65 years old, an age which entailed with his appearance and with results of clinical examinations. In patients with acute inflammatory diseases, however, these ratios were much higher than the values expected from their chronological ages. We could differentiate patients with these diseases from the controls and from the patient with Werner's syndrome with the aid of the estimation of radioactivity in the protein which decreased steadily with age in controls and was much higher in patients with acute inflammatory diseases.
These observations in human lymphocytes were well correspondent in the case of nuclear fraction of rat kidney.