Intranasal inoculation of type 5 adenovirus (AdS) produced pneumonia in mice even though the virus did not replicate. To induce the pneumonia, however, a large viral infectious dose was required-i.e., 1010 plaque-forming units.Four strains of inbred mouse were studied (C57BL/6N, C57BL/1OScN, CBA/N, and C3H/N): all showed similar inflammatory responses, although the greatest infiltration occurred in the C57BL/6N mice. The pathological response to AdS infection resembled that previously described in cotton rats: it consisted of overlapping early and late phases, and the infiltration contained primarily lymphocytes and monocytes/macrophages with a scattering of polymorphonuclear leukocytes. The prominent early phase and the presence of polymorphonuclear leukocytes suggested that induction of cytokines may play an important role in the pathogenesis ofthis pneumonia. Assays showed the appearance of tumor necrosis factor a (TNF-a), interleukin 1 (IL-1), and IL-6 in the infected mouse lungs concomitant with the developing early-phase infiltration. Only IL-6 was found in the peripheral blood. IL-6 reached maximum titers 6-24 hr after infection, whereas maximum levels of TNF-a and IL-1 were attained 2-3 days after infection. Specific RNAs for each of these cytokines were demonstrated in the infected lungs. To test the hypothesis that a cytotoxic T-cell response was responsible for the second phase, which primarily consisted of a perivascular and peribronchial infiltration of lymphocytes, AdS was used to infect C57BL/lOScN Nu/Nu and parent mice. The nude mice showed a normal early-phase response, but essentially no peribronchial and only minimal perivascular infiltrations occurred.Intranasal inoculation of type 5 adenovirus (Ad5) into the cotton rat Sigmodon hispidus initiates the development of a pneumonia that closely resembles that produced in humans (1, 2). This model was then used to investigate the viral genes required to produce the pathogenesis of the disease, which for these studies is termed "molecular pathogenesis." The results obtained, using mutants that contained defects in a 19-kDa glycoprotein, implied that the inflammatory response resulted from both the. production of cytokines and the infiltration of cytotoxic T cells (3). Thus, it was hypothesized that the first phase of the pneumonia, which consists of a lymphocyte and monocyte/macrophage intraalveolar and interstitial infiltration as well as a scattering of polymorphonuclear leukocytes (PMNs), resulted from a local elaboration of cytokines. It was further hypothesized that the second phase, which is composed of a lymphocytic perivascular and bronchiolar infiltration, was due to a virus-specific cytotoxic T-cell response.It was not readily possible to test these hypotheses in cotton rats since reagents are not available either to assay their cytokines or to identify the species of lymphocytes present in the pneumonic infiltration. It appeared possible to overcome these experimental barriers, however, when we demonstrated that H5ts125 (4), a co...

Recombinant human interleukin 1 receptor antagonist (IL-1ra) and 35F5, a neutralizing monoclonal antibody (mAb) to the type I mouse IL-1 receptor, were examined for their ability to bind to IL-1 receptors (IL- 1Rs) on various types of mouse cells and to block immune and inflammatory responses to IL-1 in vitro and in mice. IL-1ra competed for binding of 125I-IL-1 alpha to type I IL-1R present on EL-4 thymoma cells, 3T3 fibroblasts, hepatocytes, and Chinese hamster ovary cells expressing recombinant mouse type I IL-1R. The IC50 values for IL-1ra binding (ranging from 2 to 4 ng/ml) were similar to those of IL-1 alpha. In contrast, IL-1ra bound with very low affinity (IC50 values ranging from 10 to 200 micrograms/ml) to cells expressing type II IL- 1R, i.e., 70Z/3 pre-B cell line and polymorphonuclear leukocytes (PMN) derived from bone marrow and acute inflammatory exudates. The mAb 35F5 bound specifically to type I IL-1R; no inhibition of 125I-IL-1 alpha binding to cells having type II IL-1R was observed with very high concentrations of antibody. While neither IL-1ra nor 35F5 had intrinsic activity in bioassays using T helper D10.G4.1 cells and mouse thymocytes, both agents blocked the ability of IL-1 to stimulate proliferation of these cells. The effects of IL-1ra and 35F5 on acute inflammatory responses in mice were also evaluated. IL-1ra and 35F5 blocked the local accumulation of PMN after intraperitoneal injection of rIL-1 alpha. The response to IL-1 was inhibited when IL-1ra or 35F5 was administered simultaneously with or before administration of IL-1. IL-1ra and 35F5 also blocked PMN accumulation after intraperitoneal injection of lipopolysaccharide or proteose peptone, suggesting IL-1 is important in mediating responses to these agents. In addition, IL-1ra and 35F5 significantly blocked the ability of IL-1 to stimulate egress of PMN from bone marrow, to induce a transient neutrophilia, and to elevate serum levels of hepatic acute phase proteins, IL-6, and corticosterone. Thus, IL-1ra and 35F5 competitively inhibit the binding of IL-1 to the IL-1R on certain cell types. These two IL-1 receptor antagonists act to inhibit biological responses induced by IL-1 and other inflammatory agents.

Interleukin 1 (IL-1) is a polypeptide hormone that mediates a broad range ofbiological activities and interacts with surface receptors on numerous cell types. Equilibrium binding studies have identified a class of IL-1 receptors on T cells, fibroblasts, and epithelial cells that have 2-to 5-fold higher affinity than the receptors on bone marrow cells, pre-B cells, and macrophage cell lines. Affinity cross-linking with human 125I-labeled IL-la (125I-IL-1a) labels an .100-kDa protein on T cells and fibroblasts and an "80-kDa protein on pre-B cells and macrophage cell lines. Monoclonal and polyclonal antibodies specific for the IL-1 receptor on T cells and fibroblasts block human 125I-IL-la binding to T cells, fibroblasts, and epithelial cells but cannot block IL-i binding to bone marrow cells, pre-B cells, and macrophages. These antibodies immunoprecipitate the IL-1 receptor-human 125I-IL-la complex from T cells and fibroblasts but not from pre-B cells and macrophage cell lines. An S1 nuclease protection assay demonstrated that T cells and fibroblasts contain identical IL-1 receptor mRNA but that pre-B cells and macrophages do not contain this receptor mRNA. Taken together, the data demonstrate that mouse T cells, fibroblasts, and epithelial cells express an identical IL-1 receptor, whereas the IL-i receptor on pre-B cells, macrophages, and bone marrow cells represents a different gene product.Interleukin 1 proteins (IL-la and IL-13) act on a variety of cell types and have multiple biological activities (1-12). The diversity of IL-1 action is mediated by specific receptors on membranes of mouse (3, 13-17), human (17-21), rat (13), and porcine (21) cells. The binding of IL-1 is specific and saturable and occurs with high affinity (5-50 x 10-11 M) on many cell types, including T cells (3, 15-17), B cells (17, 18), fibroblasts (3, 16, 17), macrophages (22), and neutrophils (23). Both IL-la and IL-1p bind to the same receptor site on mouse (15, 24) and human (18) cells.Analysis of the structure of the IL-1 receptor by affinity cross-linking techniques identified an :80-kDa cell membrane protein on both mouse (3, 13, 17) and human (17,18) cells. An -'80-kDa IL-1 binding protein has been purified to homogeneity from the mouse EL4 thymoma cell line (25, 26), and a cDNA that encodes this protein has been isolated by expression cloning techniques from mRNA from these cells (27). An identical mRNA has been detected in 3T3-Swiss cells (27), which indicates that both fibroblasts and T cells express the same IL-1 receptor. The purified natural 80-kDa receptor from mouse EL4 cells and the recombinant EL4 type IL-1 receptor expressed in COS cells bind radiolabeled IL-1 with an affinity equal to the affinity of the cell-bound IL-1 receptor (ref. 27; R.C., P.L.K., and U.G., unpublished observations). These results indicate that a single recombinant polypeptide can duplicate the high-affinity binding of the natural membrane-bound EL4 IL-1 receptor.However, it is not known whether this 80-kDa receptor protein mediates all th...

Cytokines, including interleukin 1 (IL-1), tumor necrosis factor a, and interleukin 6, are often produced in response to tissue injury and contribute to several host responses such as weight loss, anorexia, and acute-phase protein synthesis. However, the role of IL-1 in specific tissue responses is unclear. To test our hypothesis that specific in vivo blockade of IL-l's action might inhibit the catabolic host changes associated with inflammation, mice were passively immunized with a monoclonal antibody directed against the murine IL-1 receptor prior to initiation of a turpentine-induced sterile abscess. This antibody prevents IL-i-mediated proliferation of murine thymocytes in vitro by inhibiting IL-ia and IL-liS by way of competition for a common receptor. Weight loss following turpentine challenge-was prevented by daily injections of anti-IL-i receptor monoclonal IgG. Body composition analysis confirmed that lean tissue and fat were preserved by passive immunization. Furthermore, pretreatment with an anti-IL-i receptor monoclonal antibody significantly attenuated the plasma amyloid P and interleukin 6 responses but did not affect the decline in plasma albumin or the increase in circulating corticosterone. Passive immunization of similar mice with polyclonal antisera against another cytokine, tumor necrosis factor a, failed to prevent either the weight loss or hepatic acutephase protein changes observed in this inflammatory model. These findings suggest that IL-1 orchestrates weight loss and body compositional changes during inflammation and contributes to the induction of interleukin 6 and acute-phase protein synthesis.

Interleukin 1 (IL-1) receptor antagonist (IL-