Metabolism of peripheral lymphocytes, interleukin‐2‐activated lymphocytes and tumor‐infiltrating lymphocytes from ³¹ NMR studies

31P NMR spectra of tumor-infiltrating lymphocytes (TILs) were found to be significantly different from those of normal peripheral lymphocytes. The greatest difference was in the phosphodiester (PDE) region, mainly in the glycerophosphocholine (GPC) signal. Short-term activation of peripheral lymphocytes with interleukin-2 induced a small increase in ATP levels. In all lymphocytes the phosphomonoester (PME) region is dominated by phosphoethanolamine (PE), while there is an unusual absence of phosphocholine (PC). Perfusion of these cells with high concentrations of choline caused only a minimal increase in PC, indicating that choline kinase is not the rate limiting step of lecithin synthesis in lymphocytes.