Chemotactic factor that attracts lymphocytes but not monocytes or granulocytes. May be involved in B-cell migration into B-cell follicles in lymph nodes. Attracts naive T-lymphocytes toward dendritic cells and activated macrophages in lymph nodes, has chemotactic activity for naive T-cells, CD4+ and CD8+ T-cells and thus may play a role in both humoral and cell-mediated immunity responses. Expressed at high levels in lung, lymph nodes, placenta, bone marrow, dendritic cells present in germinal centers and T-cell areas of secondary lymphoid organs and macrophages derived from peripheral blood monocytes. Not expressed by peripheral blood monocytes and a monocyte-to-macrophage differentiation is a prerequisite for expression. Expressed in synovial fluids from patients with rheumatoid and septic arthritis and in ovarian carcinoma ascitic fluid. Specifically induced in macrophages by IL4/interleukin-4, IL13/interleukin-13, and IL10/interleukin-10. Expression is inhibited by IFNG/IFN-gamma while glucocorticoids exert a slightly positive synergistic effect in combination with IL4/interleukin-4. Strongly induced in several human cell lines, including monocytic U-937 cells, by phorbol myristate acetate (PMA). Induced in PBMC by staphylococcal enterotoxins SEA and SEB. The Cys-30/Cys-54 disulfide bond is required for activity. Belongs to the intercrine beta (chemokine CC) family. CCL18 entry