Hydrocortisone selectively inhibits IgE-dependent arachidonic acid release from rat peritoneal mast cells

Purified rat mast cells were used to study the effects of anti-inflammatory steroids on the release of 1-¹⁴C]-arachidonic acid (1-¹⁴C]AA) and metabolites. Mast cells were incubated overnight with glucocorticoids, 1-¹⁴C]AA incorporated into cellular phospholipids and the release of 1-¹⁴C]AA, and metabolites determined using a variety of secretagogues. Release of 1-¹⁴C]AA and metabolites by concanavalin A, the antigen ovalbumin and anti-immunoglobulin in E antibody was markedly reduced by glucocorticoid treatment. Neither the total incorporation of 1-¹⁴C]AA nor the distribution into phospholipids was altered by hydrocortisone pretreatment. Glucocorticoid pretreatment did not alter 1-¹⁴C]AA release stimulated by somatostatin, compound 48/80, or the calcium ionophore, A23187. These data indicate that antiinflammatory steroids selectively inhibit immunoglobulin dependent release of arachidonic acid from rat mast cells. These findings question the role of lipomodulin and macrocortin as general phospholipase inhibitors and suggest that they may be restricted to immunoglobulin stimuli.