IDENTIFICATION OF CATECHOLAMINES IN THE IMMUNE-SYSTEM BY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

The first evidence that catecholamines might be present in the immune system was provided by capillary electrophoresis combined with electro chemical detection. Here, we present the first structural characteriza tion of the endogenous catecholamines isolated from human peripheral b lood mononuclear cells. Dopamine, L-DOPA and norepinephrine were detec ted and were identified with electrospray ionization mass spectrometry by determination of the protonated molecular species of each catechol amine and their major fragments generated in the electrospray source w ith a nozzle-skimmer voltage method. This technique, in conjunction wi th accurate mass measurement, allowed us to identify in an unfractiona ted sample the content of catecholamines in extracted cells in a quant itative manner, with structure-specific methodology. The data unambigu ously confirm our previous tentative findings, and also strengthen the importance of the regulatory function of catecholamines in the immune system and the existence of an autocrine loop, where lymphocytes may down-regulate their own activity. (C) 1998 John Wiley & Sons, Ltd.