MITOGEN-STIMULATED RISE OF INTRACELLULAR CALCIUM-CONCENTRATION IN SINGLE T-LYMPHOCYTES FROM PATIENTS WITH MAJOR DEPRESSION IS REDUCED

1. The authors investigated the signal transduction in T-lymphocytes a s a peripheral model for central neurons. 2. Intracellular free calciu m concentration [Ca2+](i) was measured using fura 2 in T-lymphocytes f rom 6 patients with major depression during and after depression and f rom 6 healthy controls. Patients were treated with interpersonal thera py (IPT) but not with psychotropic medication. 3. Phytohemagglutinin ( PHA) triggers an oscillatory [Ca2+](i) signal in human T-lymphocytes. This implies two mechanisms for [Ca2+](i) regulation: inositol phophat e (IF) mediated release from intracellular stores and [Ca2+](i) influx from the extracellular medium. 4. PHA stimulates 49% of T cells from controls but only 17% of T cells from depressed patients. This finding explains previous results from cells in suspension indicating that [C a2+](i) signals after PHA-stimulation are reduced in cells from depres sed patients. 5. Cells from depressed patients show less [Ca2+](i) osc illations. Normal oscillation patterns are restored after clinical rec overy from depression. 6. Thus altered [Ca2+](i) oscillations in T-lym phocytes are a state phenomenon and may give us clues where to search for altered cellular mechanisms during depression.