The macrophage inflammatory proteins -1 alpha and -1 beta were originally co-purified from medium conditioned by an LPS-stimulated murine macrophage cell line. Human MIP-1 alpha refers to the products of several independently cloned cDNAs, including LD78, pL78, pAT464, and GOS19. These cDNAs all code for the same human protein that is a homologue of the murine MIP-1 alpha. Mature MIP-1 alpha and MIP-1 beta in both human and mouse share approximately 70% homology at the amino acid level. The
MIP‑1 proteins are members of the beta (C-C) subfamily of chemokines.
Both MIP-1 alpha and MIP-1 beta are monocyte chemoattractants in vitro. Additionally, the MIP-1 proteins have been reported to have chemoattractant and adhesive effects on lymphocytes, with MIP-1 alpha and MIP-1 beta preferentially attracting CD8+ and CD4+ T cells, respectively. MIP-1 alpha has also been shown to attract B cells as well as eosinophils. MIP-1 proteins have been reported to have multiple effects on hematopoietic precursor cells and MIP-1 alpha has been identified as a stem cell inhibitory factor that can inhibit the proliferation of hematopoietic stem cells in vitro as well as in vivo. The functional receptor for MIP-1 alpha has been identified as CCR1 and CCR5.
