Glucocorticosteroid dependent decrease in the activity of calcineurin in the peripheral blood mononuclear cells of patients with systemic lupus erythematosus

Objective-To compare the activity of calcineurin in the peripheral blood mo nonuclear cells (PBMC) of 32 patients with systemic lupus erythematosus (SL E) and 35 healthy controls. Methods-The activity of calcineurin was assayed in the supernatants of soni cated mononuclear cells. Results-There was no significant difference in the calcineurin activity of patients with SLE not taking glucocorticosteroids (GCS) compared with the h ealthy controls. On the other hand, the activity of calcineurin was reduced in patients with SLE taking GCS, correlating negatively with the dose of G CS. The stimulation of PBMC by phorbol ester and calcium ionophore decrease d the calcineurin activity both in patients with SLE and in healthy control s. GCS could also reduce calcineurin activity in the mononuclear cells of h ealthy subjects in vitro. C onclusions-In patients with SLE the decrease in the calcineurin activity of PBMC depended on the dose of GCS used for treatment, and it was not a dise ase specific alteration. The higher the dose of GCS, the greater the inhibi tion of calcineurin activity. The reduction of calcineurin activity is a ne w element in the immunosuppressive effects of GCS during the treatment of p atients with SLE.