Both MIP-1alpha and MIP-1beta are structurally and functionally related CC chemokines. They participate in host response to invading bacterial, viral, parasite and fungal pathogens by regulating the trafficking and activation state of selected subgroups of inflammatory cells (e.g. macrophages, lymphocytes and NK cells). While both MIP-1alpha and MIP-1beta exert similar effects on monocytes, their effect on lymphocytes differ; with MIP-1alpha selectively attracting CD8+ lymphocytes, and MIP-1beta selectively attracting CD4+ lymphocytes. Additionally, MIP-1alpha and MIP-1beta have also been shown to be potent chemoattractants for B cells, eosinophils and dendritic cells. Both human and murine MIP-1alpha and MIP-1beta are active on human and murine hematopoietic cells. Recombinant Human MIP-1beta is a 7.6 kDa protein containing 69 amino acid residues, including the four highly conserved cysteine residues present in CC chemokines.