Macrophage inflammatory protein 1 alpha (MIP-1 alpha) is a member of t
he C-C subfamily of chemokines, a large superfamily of low-molecular-w
eight, inducible proteins that exhibit a variety of proinflammatory ac
tivities in vitro including leukocyte chemotaxis, MIP-1 alpha is a par
ticularly interesting chemokine, because in addition to its proinflamm
atory activities, it inhibits the proliferation of hematopoietic stem
cells in vitro and in vivo, Here, the biologic: properties of MIP-1 al
pha are reviewed in light of recent data on mice homozygous for a disr
uption of the MIP-1 alpha gene. The MIP-1 alpha null mice have no over
t abnormalities of peripheral blood or bone marrow cells, indicating t
hat MIP-1 alpha is not necessary for normal hematopoiesis. However, th
e MIP-1 alpha null mice have a reduced inflammatory response to influe
nza virus and are resistant to coxsackievirus-induced myocarditis, The
se data demonstrate that MIP-1 alpha is required for a normal inflamma
tory response to these viruses. Agents that inhibit the action of MIP-
1 alpha may therefore prove useful for controlling inflammation in the
se and other settings.