Human CCL16， also called HCC-4， liver-expressed chemokine （LEC）， and lymphocyte and monocyte chemoattractant （LMC）， is a novel CC chemokine recognized by bioinformatics. NCC-4 cDNA encodes a 120 amino acids along with a 23 amino acids signal peptide that is cleaved to generate 97 amino acid protein. HCC4 is vaguely related to other CC chemokines， showing less than 30% sequence identity. Among CC chemokines， CCL-16 has the largest similarity to HCC-1. 2 potential polyadenylation signals are present on the human HCC-4 gene， and as a result， 2 transcripts containing roughly 1，500 base pairs and 500 base pairs have been detected. HCC-4 is expressed weakly by some lymphocytes， including NK cells， T cells， and some T cell clones. The expression of HCC-4 in monocytes is greatly upregulated in the presence of IL-10.
CCL16 shows chemotactic activity for lymphocytes and monocytes rather than to neutrophils. NCC-4 has potent myelosuppressive activity， suppresses proliferation of myeloid progenitor cells. CCL16 demonstrates chemotactic activity for monocytes and thp-1 monocytes， rather than for resting lymphocytes and neutrophils. HCC-4 induces a calcium flux in thp-1 cells that desensitized prior to the expression of rantes.
