Adjuvant activated murine macrophages and several murine macrophage cell lines produce glucocorticosteroid response modifying factors (GRMF). These are macromolecular mediators which block the immunosuppressive effects of dexamethasone. They resemble and may be identical to mediators known as Interleukin one (IL-1). They protect both helper T cells and macrophages precursors. Studies will be done to purify GRMF and determine if the same molecules are active in the two bioassays. We will also investigate if mature macrophages are affected by GRMF and will further define the T cell subpopulations which GRMF protects.