title: Expression of a high-affinity serotonin transporter in human lymphocytes.
abstract: This study was undertaken to assess the capability of lymphocytes to actively transport serotonin (5-HT). The data we obtained showed that lymphocytes isolated from the blood of normal human subjects contained a high-affinity uptake system for [3H]5-HT. Kinetic analysis of the uptake data as computed by regression analysis from Lineweaver--Burk plots, yielded a Km of 180 +/- 20 nM and Vmax of 94 +/- pmole/10(7) cells. The uptake of [3H]5-HT was temperature, sodium and chloride dependent and was potently inhibited by the antidepressants clomipramine, imipramine, fluoxetine and fluvoxamine, which are specific for the 5-HT transporter. Compounds that are more selective for norepinephrine and dopamine transporters such as mazindol, desipramine, and GBR 19209 had a lower inhibitory effect on the uptake of [3H]5-HT in human lymphocytes. The expression of a 5-HT transporter in human lymphocytes that resembles 5-HT uptake by platelets and brain synaptosomes may provide insights into the potential role of 5-HT in immune function and its relationship to the neurobiology of affective and addictive disorders.
authors.affiliation: Department of Radiology (Division of Nuclear Medicine), Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: B A
authors.initials: BA
authors.lastname: Faraj
authors.forename: Z L
authors.initials: ZL
authors.lastname: Olkowski
authors.forename: R T
authors.initials: RT
authors.lastname: Jackson
mesh_terms: D000328:Adult; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000097:blood; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000097:blood; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D012701:Serotonin / Q000097:blood*; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D012701:Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors; C493230:SLC6A4 protein, human