Effects of Lipopolysaccharide or Recombinant Human-Interleukin-1β on Chemiluminescence by Peritoneal Macrophages from Normal and MRL-1pr/1pr Mice

Mononuclear phagocytes, under physiological conditions in a resting state, can be functionally activated by a number of stimuli (singly or in combination) both in vitro and in vivo. Amongst stimuli, some are known to prime macrophages for enhancing their level of oxidative metabolism revealed by luminol-dependent chemiluminescence (LDCL). Macrophage activation is a multi-step phenomenon which culminates to tumoricidal activity (5). This activation process is accompanied by synthesis of a variety of biologically active molecules such as Interleukin-1 (IL-1). Interleukin-1 released by macrophages can be induced in vitro by natural and synthetic bacterial immunoadjuvants such as lipopolysaccharide (LPS) (7) and Muramyl dipeptide (1). IL-1 is a polypeptide displaying a broad spectrum of biological activities (3). In this work, we compared the ability of LPS and recombinant human Interleukin-lβ (rHu-IL-1β) (Roussel-Uclaf) to prime in vivo murine peritoneal macrophage-LDCL of both normal (Balb/c and MRL-+/+) and MRL-1pr/1pr mice. MRL-1pr/lpr mice develop a systemic lupus erythematosus-like syndrome characterized by numbers of cellular and humoral abnormalities (6), such as an increase in absolute number of lymphocytes and macrophages as function of age (2, 4, 6). Peritoneal macrophages from this strain of mice spontaneously showed an increased expression of class II antigen, expression of Interleukin-2 receptor and exhibited an enhanced oxidative metabolism triggered by phorbol-ester (PMA) (2, 4).