CCL2 and nasopharyngeal carcinoma: To examine the interplay between macrophages and NPC cells, undifferentiated THP-1 monocytic cells were co-cultured with the EBV-positive NPC cell line, C666-1, in a direct contact system to examine the expression of proinflammatory cytokines including IL-6, TNFα and IL-1β, and chemokine MCP-1, as well as anti-inflammatory cytokine IL-10.