CATECHOLAMINE CONTENT AND IN-VITRO CATECHOLAMINE SYNTHESIS IN PERIPHERAL HUMAN-LYMPHOCYTES

We studied the catecholamine (CA) content in peripheral human lymphocy tes and the ability of these cells to synthesize CA in vitro. CA were separated by high performance liquid chromatography (HPLC) and determi ned in the supernatant by electrochemical detection as well as being d etermined after ultrasonic cell disruption in mononuclear leukocytes, adherent cells (monocytes/macrophages), total lymphocytes, and B- and T-cell enriched fractions. T lymphocytes contained L-Dopa and norepine phrine (NE), whereas B lymphocytes contained only L-Dopa. Lymphocytes seem to be able to synthesize NE from both L-tyrosine and L-Dopa added to the incubation medium in concentrations similar to the peripheral venous plasma (i.e. 5 x 10(-5) m and 10(-8) m, respectively). The addi tion of D-Dopa did not increase intracellular NE. alpha-methyl-p-L-tyr osine, benserazide, disulfiram, and fusaric acid (which are inhibitors of the enzymatic pathway) all decreased the synthesis of NE. After th e addition of [H-13]-L-Dopa (10(-6) m and 10(-7) m) to the incubation medium, [H-3]-NE and [H-3]-dopamine appeared. By increasing the concen tration of L-Dopa in the medium (< 10(-5) m), CA were detected in the supernatant as well. These data show that peripheral human T lymphocyt es contain and are able to synthesize CA from normal precursors in phy siologic concentrations, i.e. a CA synthetic pathway is shown in nonne ural cells. These data seem to support the hypothesis of autocrine and paracrine loops in the regulation of lymphocyte activity in lymphocyt es taken from human cerebrospinal fluid (as suggested by other authors ).