Pathways associated with immune development and activation include the role of macrophages, fibroblasts, and endothelial cells in rheumatoid arthritis, CCR5 signaling in macrophages (predicted upregulation), IL8 signaling, IL15 production, regulation of IL2 expression in activated and anergic T lymphocytes, IL1 signaling, B cell activating factor signaling, CXCR4 signaling, PKCθ signaling in T lymphocytes, leukocyte extravasation signaling, and CD27 signaling in lymphocytes (predicted upregulation). The gene discussed is IL15; the disease is rheumatoid arthritis.