Role of interferon-gamma on the in vivo expression of functional interleukin-2 receptors by murine macrophages.

Interferon-gamma activates both in vitro and in vivo macrophage functions. Injection of rat recombinant interferon-gamma (rR-IFN-gamma) induced the expression of interleukin-2 receptors (IL-2R) by peritoneal macrophages from normal BALB/c and MRL-+/+ mice. Moreover, rR-IFN-gamma stimulated in a dose-dependent manner the oxidative burst of cells as revealed by luminol-dependent chemiluminescene (LDCL). Resident peritoneal macrophages from MRL-lpr/lpr (mice that develop a systemic lupus-like syndrome) showed a higher PMA-triggered LDCL response. This enhanced activity was accompanied by an increase in IL-2R expression (30% vs. less than 1%). The "activated" macrophages from rR-IFN-gamma-treated normal mice as well as MRL-lpr/lpr mice did not respond to the addition of recombinant interleukin-2 (rHu-IL-2) by an increase in LDCL. However, rHu-IL-2 triggering became efficient when cells enriched in IL-2R-bearing macrophages were preincubated overnight with rHu-IL-2R. This response may point out a functional role for IL-2R and provide a role for IL-2 in certain macrophage functions.