The cytokines interleukin-113 and tumor necrosis factor alpha (TNF-a) (-90/-82 and -40/-32) with high homology to the nuclear factor-IL6 (NF-IL6) binding site. Site-directed mutagenesis demonstrated that the two NF-IL-6 motifs could be independently activated by LAM, LPS, or TNF-a and that they acted in an orientation-independent manner. DNA mobility shift assay revealed specific binding of nuclear protein(s) from LAM-, LPS-, or TNF-a-stimulated THP-1 cells to the NF-EL6 motifs. We conclude that the two NF-IL6 sites mediate induction of IL-11" in response to the stimuli LAM, LPS, and TNF-cx.Tuberculosis is characterized by granuloma formation with caseation necrosis and systemic symptoms of weight loss, fever, and night sweats (8). Animal models demonstrate cytokines in the granulomas, and in vitro experiments with mononuclear phagocytes have established that Mycobacterum tuberculosis stimulates the release of cytokines (5,6,25,33,40,41). Interleukin-lp (IL-1,B) and tumor necrosis factor alpha (TNF-a) are the two major inflammatory mediators released in vitro by mycobacteria (5, 13). IL-l1 is chemotactic for lymphocytes and can activate CD4+ helperinducer T lymphocytes, causing them to proliferate and release gamma interferon (IFN--y) (22). IL-1 and IFN--y stimulate macrophages to release TNF-a, which can also stimulate the release of 35). Studies of recombinant IL-1 impregnated in ethyl vinyl disks revealed that IL-1 could directly induce a granulomatous response in juxtaposition to the implanted disks (17, 27). Pulmonary granulomas induced in mice by the intratracheal injection of antigencoated beads were excised, and aqueous extracts of the granulomata contained high levels of IL-1 (26). Studies by Kunkel and colleagues demonstrated that IL-lp is the dominant cytokine in early schistosomal granuloma development, followed temporally by TNF-a (27). Thus, IL-1 may be more important to the early cellular recruitment of inflammatory cells and their activation, while TNF-a may contribute to the continued organization of the mature granulomatous lesion. Activation of the IL-1i gene is achieved by a number of stimuli, including lipopolysaccharide (LPS) from gram-negative bacteria, phorbol esters, silica, and other bacterial products (18,30,36,43).Although mycobacteria do not possess LPS, the cell wall of M. tuberculosis contains a complex lipid glycoprotein * Corresponding author. called lipoarabinomannan (LAM) which shares many physicochemical properties with LPS (5, 12). The cell wall backbone of LAM is complemented by phenolic glycolipids, mycolic acids, arabinogalactan, peptidoglycan, and mannophosphoinositides. However, the most antigenic and consequently biologically active component is LAM (10). In addition to stimulating cytokine release, LAM inhibits IFN-y activation of macrophages and protein-antigen processing by antigen-presenting cells and can suppress T-lymphocyte proliferation in vitro in response to mitogens and specific antigens (5,32,39). Barnes and colleagues demonstrated that the phosphoinosi...