CCL20 and monocytic leukemia: In human THP-1 cells, a monocytic leukemia cell line, it has been suggested that a TLR2-expressing cluster of classically differentiated macrophages exhibits the best defense response against MAP infection by increasing the expression of proinflammatory cytokines and chemokines such as IL1B, CCL4, CCL3, and CCL20 [28].