CHARACTERIZATION OF A NOVEL ANTIINFLAMMATORY FACTOR PRODUCED BY RM3 1MACROPHAGES DERIVED FROM GLUCOCORTICOID-TREATED HUMAN MONOCYTES/

Glucocorticoids exert their anti-inflammatory activity by modulating t he functions of various cell types including macrophages. They also in duce the generation of a distinct macrophage subtype defined by the su rface antigen RM3/1 which appears to be associated with the down-regul ation of inflammation. Supernatants from these cells were found to exe rt a dose-dependent antiinflammatory effect, particularly in the early phase as shown in the 5-hydroxytryptamine (5-HT) induced footpad edem a of mice. By using conventional purification methods the anti-inflamm atory factor was found to have a molecular mass of about 78 kD and an isoelectric point of about 7.9. Heat lability and sensitivity to tryps in and proteinase K indicate the protein nature of the antiinflammator y factor. The inhibition of the early phase of inflammation and the mo lecular weight suggest that the anti-inflammatory agent released from RM3/1 macrophages is a novel protein different from other antiinflamma tory proteins described so far.