NEUROPEPTIDE-Y IS AN INDUCIBLE GENE IN THE HUMAN IMMUNE-SYSTEM

This study reports on neuropeptide Y (NPY) mRNA expression in human pe ripheral blood mononuclear cells (PBMC) and lymphoid tissues. By rever se transcription polymerase chain reaction (RT-PCR) it is shown that a ctivated human PBMC of normal blood donors expressed the NPY gene. The PCR products had the expected size and Northern blotting demonstrated the presence of the 0.8-kb NPY mRNA. To define the subpopulations of mononuclear cells expressing this neuropeptide, purified monocytes, B cells and T cells were stimulated with specific activators. Monocytes and in vitro matured macrophages expressed NPY mRNA in response to pho rbol myristate acetate (PMA). B lymphocytes expressed NPY mRNA followi ng stimulation with antibody to surface immunoglobulin and PMA. In ord er to analyze whether these cell types express NPY under physiological conditions in vivo, human bone marrow, tonsil and thymus were analyze d. In situ hybridization of bone marrow revealed a small number of cel ls containing high levels of NPY mRNA which was also detected in RNA e xtracts of human thymus and tonsil. In summary, NPY is an inducible ge ne in human lymphocytes and monocytes and it is expressed at sites whe re these cells are activated in vivo.