Lipid composition of the mouse spleen in Rauscher leukaemia.

Lipid constituents were examined in the spleen of mice 10, 14 and 18 days after infection with Rauscher leukaemia virus. (i) The total lipid content, as related to the amount of protein, decreased with the development of the tumour. (ii) Spleen cells of control and infected mice synthesized the same lipids. (iii) In the infected spleen, free fatty acids increased by 80% and triglycerides decreased by 44% as compared to the control. The percentage distribution of phospholipid components showed a change in tumour cells: lecithin and phosphatidylethanolamine increased, lysolecithin and sphingomyelin decreased. (iv) After intraperitoneal injection of [32P] orthophosphate, in infected mice the incorporation of 32P into phosphatidylcholine and phosphatidylethanolamine increased, while 32P incorporation into lysophosphatidylcholine + sphingomyelin and phosphatidylinositol + phosphatidylserine fractions decreased.