MDC is a CC chemokine that is produced in B cells, macrophages, monocyte-derived dendritic cells, activated NK cells and CD4 T cells. It signals through the CCR4 receptor. MDC chemoattracts monocytes, dendritic cells and NK cells and exerts HIV suppressive activity. The 67 amino acid form of MDC displays reduced chemoattractant activity but retains HIV suppressive activity. Recombinant human MDC is an 8.1 kDa protein containing 69 amino acid residues including the four highly conserved cysteine residues present in the CC chemokines.