PREDNISONE INCREASES PGH-SYNTHASE-2 IN ATOPIC HUMANS IN-VIVO

We compared the expression of prostaglandin H synthase-2 (PCHS-2, cycl ooxygenase) message and protein in alveolar macrophages (AM) and blood monocytes (BM) from 20 atopic subjects (AS) and nine control subjects (CS) at baseline and after 1 to 14 d of oral administration of therap eutic doses of prednisone. At baseline, the amounts of PGHS-2 mRNA in AM and BM varied within a similar range among subjects from each group . PCHS-2 protein was present in AM and BM from most AS, but it was als o present in CS. In AS, PCHS-2 mRNA and protein significantly increase d after prednisone administration, whereas in CS PCHS-2 message and pr otein remained undetectable or, if present at baseline, was decreased after prednisone. Ex vivo both atopic and normal monocytes and macroph ages exhibited the expected decrease in stimulated PCHS-2 mRNA with gl ucocorticoids. PGHS-1 expression was not altered by prednisone in eith er group. The differential regulation of the inducible PGHS isoform by prednisone may be mediated by effects on cytokine production in AS.