Decreased arachidonic acid release in peripheral blood monocytes of patients with systemic lupus erythematosus

Objective. To investigate the release of arachidonic acid (AA) in unfractionated peripheral blood mononuclear cells (PBMC), separated monocytes and T lymphocytes of patients with systemic lupus erythematosus (SLE). Methods. AA release was measured in cells from 56 patients with SLE and from 48 controls. Of the 56 patients with SLE, 38 were receiving glucocorticosteroids and 18 were not. [H-3]AA was incorporated into the membranes of PBMC and purified subsets of monocytes and T lymphocytes. The release of [H-3]AA was measured both in nonstimulated cells cultured for 24 h and in cell cultures stimulated by phorbol ester (PMA) and Ca2+ ionophore for 4 h. Results. In the PBMC of SLE patients not taking glucocorticosteroids, the release of AA was decreased in both stimulated and nonstimulated cells. There was a decrease of AA production in monocytes but not in T lymphocytes, This phenomenon could be observed in the active and inactive phases of the disease. Conclusion. A defect in AA production may exist in the peripheral monocytes of patients with SLE, resulting in decreased release of AA in patients not receiving glucocorticosteroid therapy.