Cytosolic free [Ca²⁺] in single T-lymphocytes from depressed patients and healthy controls

Summary

Human lymphocytes are widely used as peripheral models for central neurones. Alterations in immune function have been reported in depressed patients, e.g. mitogen-induced proliferation is impaired during depression. One possible causative mechanism could be altered [Ca²⁺]_i regulation. Phytohaemagglutinin (PHA)-induced rise of [Ca²⁺]_i has been found to be diminished in lymphocyte suspensions from depressed patients (Ecker et al., this issue). We measured PHA-induced rise of [Ca²⁺]_i in single Fura-2 AM-loaded T11⁺ lymphocytes of patients with major depression and controls to further analyse [Ca²⁺]_i regulation in depression.

The [Ca²⁺]_i of resting lymphocytes was 57±2 nmol/l (mean ± SEM). There was no difference in resting [Ca²⁺]_i of resting lymphocytes of patients and controls. PHA evoked an increase of [Ca²⁺]_i an 7 out of 14 cells from control subjects up to 400–500 nmol/l. In contrast, only 4 out of 13 cells from depressed patients showed an increase of [Ca²⁺]_i up to 200 nmol/l. In a small fraction of cells from both groups the [Ca²⁺]_i signal is oscillating.

Our preliminary data confirm alteration of [Ca²⁺]_i regulation in lymphocytes of depressed patients.