IL-1 alpha inhibits lymphocyte migration into a site of chronic inflammation.

The effects of murine recombinant IL-1 alpha (muIL-1 alpha) on lymphocyte migration in the mouse have been investigated. Continuous infusion of muIL-1 alpha had marked effects on patterns of lymphocyte migration into a site of chronic inflammation, inflammatory exudate and spleen; the numbers of lymphocytes migrating to the inflamed tissue and spleen were reduced in a dose-dependent manner. The number of lymphocytes in the blood of muIL-1 alpha-treated animals was increased in a dose-related manner. The decrease in numbers of lymphocytes present in the chronically inflamed site may either be due to a direct inhibitory action of muIL-1 alpha or reflect an increased rate of cell migration through the inflamed tissues accompanied by a more rapid return to the circulation. These findings suggest that IL-1 alpha may act not only as an inflammatory cytokine, but also as a modulator with anti-inflammatory activity during chronic inflammation.