The objectives of the proposed research are two-fold: 1) to study the mechanism of induction and release of human monocyte factor (MCF, LAF, In terleukin 1) in response to various immunological stimuli; and 2) to study the roles of neutral proteinases activated at the plasma membrane, or released into the cell micro-environment, in the digestion of connective tissue substrates by human mononuclear phagocytes, fibroblasts, dendritic cells or chondrocytes. The hypothesis to be examined is that the consequences of immune complex-macrophage interactions either lead to enzymatic activation at the plasma membrane, producing damage to adjacent tissues, or to release of soluble substances that amplify the effector function of other cells in tissue destruction. The methods to be used include in-vitro systems for determining the relative effectiveness of various forms of immune complexes in stimulating human monocytes and macrophages to synthesize and release soluble factors (MCF) that amplify collagenase secretion by fibroblasts, synovial dendritic cells or chondrocytes. These same systems also will be employed to explore the mechanism of immune complex or Fc fragment-stimulated MCF production in human monocytes. In addition, ultrastructural cytochemical localization techniques will be employed to search for the presence of active neutral proteinases at the surface of these cells after stimulation with immune complexes. Other studies will utilize radiolabelled monolayers of collagen or proteoglycans to compare the direct degradation induced by cells cultured on these substrates with the release of specific enzymes or inhibitors into the supernatant.
