Evidence has been obtained that catecholamines and their metabolites are present in single lymphocytes and extracts of T- and B-cell clones by use of capillary electrophoresis with electrochemical detection. Pharmacological inhibition of tyrosine hydroxylase reduces observed catecholamine levels, suggesting catecholamine synthesis by lymphocytes. Intracellular dopamine levels are shown to be increased by extracellular dopamine, suggesting a cellular-uptake mechanism. Furthermore, incubation with either dopamine or L- dihydroxyphenylalanine, a precursor of dopamine, results in a dose-dependent inhibition of lymphocyte proliferation and differentiation. Together, these results suggest the presence of an autocrine loop whereby lymphocytes down- regulate their own activity.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Dec 20 1994|
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