Transient changes in phospholipid methylation induced by dexamethasone in lymphoid cells.

We have investigated the effect of dexamethasone on phospholipid methylation by chronic lymphatic leukemia cells in culture. Methyl transfer from S-adenosyl[methyl-3H]methionine into lipid fraction showed a sharp rise within 2 to 3 hr of dexamethasone treatment. After 6 hr of dexamethasone treatment, however, methylation decreased below the control levels and remained lower thereafter. Analysis of the lipid components indicated that the formation of phosphatidylmonomethylethanolamine was not affected by dexamethasone. However, phosphatidylcholine synthesis by the transmethylation pathway showed an initial increase followed by a decrease. The results point to the possibility that this effect may have physiological significance in the lymphocytolytic effects of glucocorticoids.