Described are preferred processes for suppressing proliferation of or for myeloprotecting myeloid cells in mammals. The processes involve the use of chemokines of the group Macrophage Inflammatory Protein-2.alpha. (MIP-2.alpha.), Platelet Factor 4 (PF4), Interleukin-8 (IL-8) and Macrophage Chemotactic and Activating Factor (MCAF), or involve the use of these chemokines or Macrophage Inflammatory Protein-1.alpha. (MIP-1.alpha.) in synergistic combinations or while they are substantially completely in monomeric form (i.e. substantially free from their polymerized or aggregated forms).