Changes in the DNA of lymphocytes from pristane treated rats.

The effects of pristane (2,6,10,14-tetramethylpentadecane) on the cellular DNA of lymphoid cells from Copenhagen rats were examined by flow cytometry. Significant reductions in the mean relative fluorescent intensities of propidium iodide (PI) stained lymphocytes from peripheral blood, spleen, thymus and lymph nodes were observed after a single intraperitoneal injection of pristane. The altered PI staining characteristics were observed as early as 4 days and reached a maximum decrease between 1-4 weeks (depending upon the lymphoid cells examined) post pristane treatment. The pristane-induced effects on peripheral blood lymphocytes were observed to be dose dependent, transient and reinducible by a subsequent exposure to pristane. Further analyses, using gas-liquid chromatography to detect pristane in the blood and lymphoid tissues of treated rats, indicated significant increases over normal amounts of pristane. Furthermore, correlations existed between the times of maximum decrease in the fluorescence of PI stained cells and the amounts of pristane detected within the respective lymphoid tissues. By contrast no changes in the PI staining characteristics of kidney cells were observed, even though appreciable amounts of pristane were detected in this organ. Diphenylamine analyses indicated no differences in the amounts of DNA in lymphoid cells from pristane treated and untreated rats. Furthermore, lymphocytes from pristane-treated rats did not exhibit decreased fluorescence when fixed at pH 10 rather than pH 7.4 prior to PI staining. Collectively these results suggest that pristane may preferentially induce qualitative rather than quantitative changes in the DNA of lymphocytes.