Lymphocytes induce monocyte chemoattractant protein-1 production by renal cells after Fcγ receptor cross-linking: role of IL-1β

Abstract

Leukocyte recruitment to the kidney in immune complex disease like systemic lupus erythematosus (SLE) is mediated in part by local expression of chemokines such as monocyte chemoattractant protein-1 (MCP-1). Recent studies from this laboratory demonstrated that cross-linking Fc gammaR on lymphocytes causes release of a soluble factor that induces monocyte chemokine production. To explain the induction of renal chemokine expression in immune complex disease, we postulated that this lymphocyte factor stimulates renal parenchymal cell MCP-1 expression. To test this hypothesis, human peripheral blood lymphocytes were incubated on immobilized IgG, a model for immune complex Fc gammaR cross-linking. Supernatants from these lymphocyte cultures significantly increased MCP-1 production by human mesangial, glomerular capillary endothelial, and proximal tubular epithelial cells. Mesangial cells incubated on immobilized IgG or with soluble, preformed immune complexes did not secrete MCP-1 above control levels. Lymphocyte supernatant-induced MCP-1 production appeared to be dependent on the presence of interleukin (IL)-1beta in the supernatant. Removing IL-1beta from the supernatants, antagonizing its activity, or preventing conversion to mature IL-1beta abrogated renal cell MCP-1 expression by the lymphocyte supernatants. These data demonstrate that in response to cross-linking Fc gammaR, lymphocytes induce renal cell MCP-1 expression by secreting IL-1beta. Renal chemokine expression in immune complex disease may thus be triggered as lymphocytes traffic through the kidney and encounter deposited immune complexes.