Immune interferon (IFN-y) released by stimulated T lymphocytes is believed to be the major macrophage activating factor (MAF) (1). IFN-y affects the genetic program of macrophages, and increases the expression of major histocompatibility complex class II antigens and of the immunoglobulin Fc receptor (1). Depending upon their state of activation, macrophages release a number of proteins that are thought to play an important role in inflammation, such as interleukin 1 (IL-1) (1) and the urokinase-type plasminogen activator (u-PA) (2). Tumor necrosis factor/cachectin (TNF-a) is also a macrophage product, and it is released in large amounts upon stimulation by bacterial endotoxin (LPS). TNFa has a broad range of biological activities, including a cytotoxic effect against certain tumor cells and participation in the destruction of parasites (3).To further explore the mode of action of IFN-y on macrophages, we chose to study its effect on the expression of the genes coding for these secreted proteins . We show here that IFN--y enhances transcription of the TNF-a, IL-1, and u-PA genes in mouse peritoneal macrophages, resulting in a large increase in their mRNA levels . While investigating whether these effects of IFN-y require the synthesis of new proteins, we observed that the inhibition of protein synthesis by cycloheximide rapidly induces the transcription of these three genes, which thus appears to be under the control of short-lived repressors . Volume 164 December 1986 2113-2118 Materials and Methods Brief Definitive ReportMacrophage Culture. Peritoneal exudate cells were recovered from 3-5-mo-old AKR, CBA/J, B10A, or C3H/Hej mice 4 d after a single intraperitoneal injection of 1 ml of aged thioglycollate broth (2 .9 g/ml ; Difco, Detroit, MI), and incubated for 10-18 h in DMEM (Gibco Laboratories, Grand Island, NY) supplemented with penicillin, streptomycin, pyruvate, and 5% heat-inactivated (56°C, 30 min) FCS; the adherent macrophages population (2) was then washed with PBS and reincubated with supplemented DMEM for at least 1 h before start of the experiments. Adherent resident peritoneal cells were prepared in a similar way.Isolation and Analysis of Macrophage RNA. Isolation of total cellular RNA and hybridThis work was supported by grants 3.075 .0 .84 and 3.614 .084 from the Fonds National Suisse de la Recherche Scientifique, and by the Sir Jules Thorn Charitable Trust.J. EXP. MED.

Bacterial sepsis is characterized by a systemic inflammatory state, with activation of numerous cell types. Phagocytes participate in this phenomenon by secreting various proinflammatory cytokines and enzymes. Matrix metalloproteinases (MMPs) such as gelatinases are produced by phagocytes and are thought to play an important role in processes of cell transmigration and tissue remodeling. In this work, we show that endotoxin (lipopolysaccharide [LPS]) and other inflammatory mediators, such as tumor necrosis factor (TNF), interleukin-8, and granulocyte colony-stimulating factor, induce a rapid (within 20 min) release of gelatinase-B (MMP-9) zymogen in whole human blood, as determined by gelatin zymography. The polymorphonuclear neutrophil was identified as the cell responsible for this rapid secretion, as a result of the release of preformed enzymes stored in granules. Normal human subjects given LPS intravenously showed a similar pattern of proMMP-9 secretion, with maximum plasma levels reached 1.5 to 3 h after LPS administration (P = 0.0009). Prior administration of TNF receptor:Fc, a potent TNF antagonist, to subjects given LPS, only partially blunted the release of proMMP-9 (P = 0.033). Ibuprofen, a cyclooxygenase inhibitor, did not alter this pattern of release. Increased levels of proMMP-9 and proMMP-2, as well as activated forms of MMP-9, were found in plasma from two patients with gram-negative sepsis. The levels of MMPs paralleled the severity of clinical condition and a marker of the severity of sepsis, plasma procalcitonin. These data indicate that MMPs are released in whole blood in response to various inflammatory mediators and that they could serve as sensitive and early markers for cell activation during the course of bacterial sepsis.

In this study, we examined the effects of interleukin‐10 (IL‐10) on the outcome of experimental cerebral malaria (CM), a lethal neurological syndrome that occurs in susceptible strains of mice after infection with Plasmodium berghei ANKA (PbA). Constitutive IL‐10 mRNA levels were significantly higher in the spleen and brain of resistant animals. In vivo neutralization of endogenous IL‐10 in CM‐resistant mice induced the neurological syndrome in 35·7% of these mice, as opposed to 7·7% in controls. IL‐10 inhibited PbA antigen‐specific interferon‐γ (IFN‐γ) production in vitro but not tumour necrosis factor (TNF) serum levels in vivo. Susceptible mice, on the other hand, were significantly protected against CM when injected with recombinant IL‐10. Overall, our findings suggest that IL‐10 plays a protective role against experimental cerebral malaria.

Mouse interleukin 3 (IL-3) cDNA was cloned into a plasmid construction, allowing the synthesis of very high quantities ofIL-3 in Escherichia coli. The recombinant (r) IL-3, purified to homogeneity, was active in vitro on the proliferation and differentiation of various hematopoietic progenitor cells at 1 pM. To maintain detectable blood levels of IL-3, osmotic pumps containing rIL-3 or control solutions were placed under the skin of normal and irradiated C3H/HeJ and (BALB XB1O) F1 mice. The effect of IL-3 on hematopoietic progenitor cell numbers in spleen and bone marrow was evaluated 3 and 7 days later by using an in vitro clonal assay. The results demonstrated the following: (i) Doses of IL-3 infused at the rate of 2.5-5 ng per g of body weight per hr were sufficient to increase the numbers of hematopoietic progenitors in normal mice by at least 2-fold within 3 days. (ii) In mice with progenitor cell levels depressed by sublethal irradiation, 7-day treatment with IL-3 resulted in a 10-fold increase to near normal levels. (iiW) The erythroid and myeloid lineages appeared to be enhanced to the same extent. (iv) Enhancement of hematopoiesis occurred primarily in spleen, but hematopoietic foci were also evident in the liver; in contrast, total cell and progenitor cell numbers were decreased in the bone marrow.

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