Hyperexpression of ICAM-1 and CD36 in placentas infected with Plasmodium falciparum: a possible role of these molecules in sequestration of infected red blood cells in placentas

AIMS

During pregnancy, Plasmodium falciparum malaria is frequent and associated with maternofetal complications. This could be the consequence of sequestration by several adhesion molecules of parasite-infected red blood cells in syncytiotrophoblast. To investigate the expression of ICAM-1 and CD36, two of the adhesion molecules for Plasmodium falciparum, an immunohistochemical study was carried out in malaria-infected placentas.

METHODS AND RESULTS

Thirty-five infected and 35 noninfected samples were chosen randomly. According to the histological classification of Bulmer, the infected placentas were separated in three groups: active, active chronic and past-chronic infection. CD36 was localized in the cytoplasm of stromal cells of terminal villi of infected or noninfected placentas, but not in syncytiotrophoblast. ICAM-1 was detected in the cytoplasm of stromal and endothelial villous cells in both infected and noninfected placentas and in syncytiotrophoblast of eight infected placentas showing more frequently active than active chronic or past-chronic infection (P < 0.001). The percentage of cells immunostained for CD36 or ICAM-1 was evaluated in the terminal villi. The proportion of villous cells, with ICAM-1 and CD36 immunostaining, was significantly higher in infected vs. noninfected placentas (P < 0.0001) and CD36 was detected more in acute inflammatory vs. past-chronic inflammatory placentas (P < 0.05).

CONCLUSIONS

The higher expression of ICAM-1 in infected placentas and its localization in syncytiotrophoblast particularly during acute infection, suggest ICAM-1 can act directly in the sequestration of parasite-infected red blood cells (IRBCs). On the other hand, the expression of CD36 is influenced by the presence of IRBCs without being directly implicated in sequestration of IRBCs. The hyperexpression of these two molecules could explain the high frequency of malaria during pregnancy.

Antigenic variation of Borrelia turicatae Vsp surface lipoproteins occurs in vitro and generates novel serotypes

As a means of avoiding the host immune response, the tick-borne relapsing fever spirochete Borrelia turicatae undergoes antigenic variation in its abundant surface lipoproteins. In this study, B. turicatae strain Oz1, serotype B, was subcultured in vitro and cloned by limited dilutions after 50 passages. Four different serotypes (serotypes A, B, E, and F) differing by their expressed Vsp lipoproteins were isolated. Using pulsed-field gel electrophoresis, we showed that the variability in surface-exposed proteins is correlated with rearrangement between different linear plasmids, defining serotype-specific plasmid profiles. Moreover, we determined the nucleotide sequence of genes encoding the VspE and VspF lipoproteins, corresponding to the two novel serotypes E and F, respectively. Our results showed that antigenic variation in B. turicatae occurs spontaneously in vitro, in the absence of immune selection.

[Adiaspiromycosis, 2 cases of incidental finding]

Two apparently solitary granulomas, each containing an adiaconidia, 200 and 300 microm in diameter, were incidentally found in the lung parenchyma on a pleuro-pneumonectomy specimen for malignant mesothelioma, and in the stroma of a pulmonary adenocarcinoma, respectively. These two cases of adiaspiromycosis illustrate well the characteristic morphology of this strictly pulmonary, rare, ubiquitous, and histologically diagnosed mycosis.

[Squamous cell carcinoma arising from chromomycosis. Report of two cases]

Madagascar is the principal area of endemic chromomycosis in the world with 1 400 cases registered from 1955 to 1996. Malignant transformation is rare and only 12 cases have been reported. We describe herein two new cases of squamous carcinoma arising from chronic lesions of chromomycosis. These carcinomas which develop slowly and are non invasive, are similar to those arising from burns, tropical phagedenic ulcers and chronic leprosy ulcers. Epidemiological aspects, histopathology and treatment are described.

Enhanced sensitivity of tumor necrosis factor/lymphotoxin-alpha-deficient mice to Cryptococcus neoformans infection despite increased levels of nitrite/nitrate, interferon-gamma, and interleukin-12

The cytokine network and infection severity were characterized during disseminated cryptococcosis in tumor necrosis factor (TNF)- and lymphotoxin (Lt)-alpha-deficient mice. On day 16, the fungus burden was higher and median survival time was reduced, as was polymorphonuclear leukocyte infiltrate in the brains of knockout mice. TNF/Lt-alpha-deficient mice had lower levels of interleukin (IL)-6 in lungs and brains, IL-1beta, and the chemokine KC in brain and spleen and of the chemokine monocyte chemoattractant protein (MCP)-1 in spleen than control animals. In contrast, higher levels of IL-6, IL-10, and MCP-1 in plasma and higher levels of IL-12, interferon (IFN)-gamma, and nitrite/nitrate were found in all compartments of TNF/Lt-alpha-deficient mice. These data confirm that TNF or Lt-alpha is a key cytokine for the anticryptococcal response and demonstrate its major role for the induction of IL-1beta, IL-6, and KC in the brain; however, its presence is not a prerequisite for IL-12, IFN-gamma, and nitrite/nitrate production.

[Disseminated histoplasmosis detected by lingual and tonsillar erosions in an immunocompetent patient]

BACKGROUND

Histioplasmosis is a usually asymptomatic fungal infection. In the immunocompetent patient, it leads to chronic disseminated infection. Mucosal involvement is common and can provide the diagnosis.

CASE REPORT

A metropolitan Frenchman with a history of alcoholism and smoking and living in Guyana consulted for lingual and tonsil erosion. Squamous cell carcinoma was suspected but not confirmed at pathology. The patient had a bi-apical infiltration on the chest x-ray and was treated empirically for tuberculosis. The diagnosis of histoplasmosis was reached when rare Histoplasma capsulatum were evidenced from a buccal swab. Itraconazole led to cure in 6 months.

DISCUSSION

This case illustrates the importance of mucosal signs in the diagnosis of disseminated histoplasmosis in immunocompetent subjects. Histoplasmosis is rarely the cause of active infection in immunocompetent subjects. In these patients, the fungal infection generally progresses to chronic dissemination. Mucosal signs are frequent in this form but are rare in case of cutaneous histoplasmosis. Itraconazole (200 mg/d) is indicated for 6 months.

Specific detection of fusarium species in blood and tissues by a PCR technique

Fusarium species are opportunistic nosocomial pathogens that often cause fatal invasive mycoses. We designed a primer pair that amplifies by PCR a fragment of a gene coding for the rRNA of Fusarium species. The DNAs of the main Fusarium species and Neocosmospora vasinfecta but not the DNAs from 11 medically important fungi were amplified by these primers. The lower limit of detection of the PCR system was 10 fg of Fusarium solani DNA by ethidium bromide staining. To test the ability of this PCR system to detect Fusarium DNA in tissues, we developed a mouse model of disseminated fusariosis. Using the PCR, we detected Fusarium DNA in mouse tissues and in spiked human blood. Furthermore, F. solani, Fusarium moniliforme, and Fusarium oxysporum were testing by random amplified polymorphic DNA (RAPD) analysis. The bands produced by RAPD analysis were purified, cloned, and sequenced. The information was used to design primer pairs that selectively amplified one or several Fusarium species. The method developed may be useful for the rapid detection and identification of Fusarium species both from culture and from clinical samples.

Quantitative computer image analysis of chondroitin sulfate A expression in placentas infected with Plasmodium falciparum

Most pathological conditions resulting from infection with the human malaria parasite Plasmodium falciparum occur as a consequence of the sequestration by several adhesion molecules of parasite-infected red blood cells (IRBCs). Recent reports have provided evidence that placental vascular endothelial ligands for IRBCs were mostly restricted to chondroitin sulfate A (CSA). The expression of CSA in malaria-infected placentas was investigated in a prospective case-control study in a hypoendemic area (Dakar, Senegal). The tissue distribution of CSA was measured in the terminal villi by immunostaining combined with image processing in 20 infected and 20 noninfected frozen sections of placenta. The villous surface immunostained by anti-CSA antibody was higher in infected than in noninfected placentas (p<0.03), in placentas with active infection than in those with past chronic infection (p<0.05), and in infected placentas with positive imprints than in those with negative imprints (not significant; p=0.06). Labeling was found in the extracellular matrix and in endothelial and stromal cells of all the placentas. Syncytiotrophoblast immunostaining was detected in all placentas associated with active or active chronic infection (n=7) but in only 4/13 placentas with past chronic infection (p<0.01). The presence of P. falciparum in the imprint was significantly correlated with immunostaining of CSA in syncytiotrophoblasts (p=0.003). These results suggest that CSA can play an important role in the sequestration of P. falciparum in human placentas during the acute phase of infection.

Suppression of immediate and late responses to antigen by a non-anaphylactogenic anti-IgE antibody in a murine model of asthma

Eosinophils are recruited to the airways during allergic reactions, but animal models have shown that their mere presence is not sufficient for the development of bronchopulmonary hyperreactivity. Other factors, such as immunoglobulin (Ig)E, seem to be required. Using mice selected for the production of large amounts of IgE, the effects of antibody neutralization of IgE on antigen-induced lung recruitment of eosinophils and induction of bronchopulmonary hyperreactivity and of other indicators of inflammation were studied. A monoclonal non-anaphylactogenic rat anti-mouse IgE (mAb1-5), given within 24 h of the challenge with antigen, reduced tissue eosinophilia, the recruitment of IgE-bearing cells identified as basophils, mucous cell metaplasia, anaphylactic bronchoconstriction and bronchopulmonary hyperreactivity. mAb1-5 inhibited interleukin (IL)4 titres in the bronchoalveolar lavage fluid, but not those of I1-5. Inhibition by mAb1-5 may result from competitive displacement of immunoglobulin E from its different receptors, thus preventing cell stimulation. Moreover, the inhibition of the massive recruitment of immunoglobulin E-bearing basophils into the lungs within hours after challenge and of interleukin4 production by mAb1-5 may be important factors leading to the reduction of pulmonary eosinophilia and bronchopulmonary hyperreactivity. Thus, immunoglobulin (Ig)E and allergic IgE-bearing cells seem to play an essential role in the initial development of the late allergic airway responses.

Mucous-cell metaplasia and inflammatory-cell recruitment are dissociated in allergic mice after antibody- and drug-dependent cell depletion in a murine model of asthma

Inflammatory-cell infiltration and epithelial modifications are prominent lesions of the bronchial mucosa in asthma and in experimental allergic bronchopulmonary inflammation. However, the recruitment of inflammatory cells and their relationship to the epithelial modifications and to functional alterations such as bronchopulmonary hyperreactivity (BHR) are less known. We studied the mechanisms of antigen-dependent inflammatory-cell recruitment to the lungs and the associated lesions and their relationship using drug- and antibody-dependent cell-depletion procedures. A single intranasal ovalbumin challenge in BP2 mice was found to induce hyperreactivity within 1 h after challenge, followed by the massive infiltration of immunoglobulin (Ig)E-bearing polymorphonuclear leukocytes (PMN), and eosinophils, and by a mucous-cell metaplasia of the bronchiolar epithelium. Similarly challenged BALB/c mice did not exhibit BHR, despite a moderate recruitment of inflammatory cells and mucous-cell metaplasia. Inflammatory-cell recruitment, mucous-cell metaplasia, and BHR were prevented by prior antibody-dependent depletion of CD3(+) lymphocytes and partially inhibited by the depletion of CD4(+) lymphocytes. Treatment with the granulocytopenic drug vinblastine before challenge completely abolished the recruitment of granulocytes without affecting the antigen-induced mucous-cell metaplasia. In this study two new key elements of the murine model of allergic pulmonary inflammation are described: the recruitment of IgE-bearing PMN between 3 and 72 h after challenge, and the dissociation between granulocytes and mucous-cell metaplasia.

Murine natural killer T(NKT) cells [correction of natural killer cells] contribute to the granulomatous reaction caused by mycobacterial cell walls

Mice injected with deproteinized cell walls prepared from the strain H37rv of Mycobacterium tuberculosis develop a granuloma-like lesion in which NKT cells are predominant. NKT cells play a primary role in the granulomatous response, because the latter does not occur in Jalpha281(-/-) mice, which miss NKT cells. The glycolipidic fraction of the cell walls is responsible for the recruitment of NKT cells; the recruiting activity is associated with fractions containing phosphatidylinositolmannosides. These results define a powerful experimental set up for studying the in vivo induction of NKT cell responses to microbial components.

Interleukin-8 controls bacterial transepithelial translocation at the cost of epithelial destruction in experimental shigellosis

In shigellosis, the network of cellular interactions mediated by a balance of pro- and anti-inflammatory cytokines or chemokines is clearly tipped toward acute destructive inflammation of intestinal tissues by the bacterial invader. This work has addressed the role played by interleukin-8 (IL-8) in a rabbit model of intestinal invasion by Shigella flexneri. IL-8, which is largely produced by the epithelial cells themselves, appears to be a major mediator of the recruitment of polymorphonuclear leukocytes (PMNs) to the subepithelial area and transmigration of these cells through the epithelial lining. Neutralization of IL-8 function by monoclonal antibody WS-4 caused a decrease in the amount of PMNs streaming through the lamina propria and the epithelium, thus significantly attenuating the severity of epithelial lesions in areas of bacterial invasion. These findings are in agreement with our previous work (31). In contrast to the PMNs, the bacteria displayed increased transepithelial translocation, as well as overgrowth in the lamina propria and increased passage into the mesenteric blood. By mediating eradication of bacteria at their epithelial entry site, although at the cost of severe epithelial destruction, IL-8 therefore appears to be a key chemokine in the control of bacterial translocation.

A case of Aspergillus myocarditis associated with septic shock

We report a case of isolated myocardial involvement due to Aspergillus sp., in a patient with multiple organ failure but no demonstrable immune deficiency apart from corticosteroid therapy given for the three weeks prior to hospitalization. This patient died of septic shock 7 days after hospitalization. Aspergillus was isolated only once from a sputum specimen obtained 24 h before death. At post-mortem examination there are emboli and myocardial lesions containing clusters of hyphae as Aspergillus confirmed by indirect immunofluorescence. The other organs were free of fungi. This observation is remarkable because the cardiac involvement was isolated and no immunodeficiency was present.

[Cutaneous Alternaria infectoria infection after liver transplantation]

We report a case of cutaneous alternariosis after liver transplantation. This rare phaeohyphomycosis is mainly observed in patients treated by corticosteroids. This case is remarkable for the species isolated: Alternaria infectoria. Clinical and histopathological features are studied and diagnostic problems are discussed.

Systemic administration of endotoxin induces bronchopulmonary hyperreactivity dissociated from TNF-alpha formation and neutrophil sequestration into the murine lungs

Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-alpha were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-alpha and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophils in the pulmonary microvasculature nor to the synthesis of TNF-alpha.

Cutaneous T cell lymphomas: mycosis fungoides, Sezary syndrome and HTLV-I-associated adult T cell leukemia (ATL) in Mali, West Africa: a clinical, pathological and immunovirological study of 14 cases and a review of the African ATL cases

Cutaneous T cell lymphomas (CTCL) are rare lymphoproliferative diseases, which are frequently suspected to be of viral origin. As very few data were available concerning cutaneous T cell lymphomas in tropical Africa, we undertook a clinical, histopathological, immunological and viro-molecular study of patients with a clinical diagnosis of cutaneous lymphoma, in Bamako, Mali. While prior to this study, no case of CTCL had been reported in this country, 14 patients (five women, nine men; mean age 58 years) with a diagnosis of cutaneous lymphoma were seen over a period of 30 months (1992-1994) in the only dermatological department in Mali. Clinically, the most frequent pattern was an infiltrated erythrodermia similar to Sezary syndrome. Nodular lesions and/or plaques were rarely observed. All these cutaneous tumors were T cell lymphoproliferations, only one expressing the CD8+ antigen. A comprehensive analysis of all the available data permitted characterization of three cases of adult T cell leukemia/lymphoma (ATL) associated with HTLV-I (one definitive case, of leukemic type, with demonstration of clonal integration of HTLV-I proviral genome and two probable ATL cases), three cases of Sezary syndrome (SS), two cases of mycosis fungoides (MF) and five cases of pleomorphic cutaneous lymphoma. In one case, the differentiation between MF and pleomorphic cutaneous lymphoma could not be established. HTLV-I serological and/or molecular markers were restricted to the three ATL cases. From the unique definitive ATL case, a T cell line was established from culture of peripheral blood mononuclear cells and sequence analysis of the env gene and the U3-LTR region demonstrated that the virus present in this patient belonged to the cosmopolitan subtype A. Thus, we report here the first evidence of HTLV-I infection and associated ATL in Mali. This is the second ATL case described for the whole Sahelian region (one ATL of the lymphoma type was reported previously in a Mauritanian patient). Furthermore, we demonstrate that the main types of CTCL described in Europe and North America are also present in this African area and that the prevalence of these diseases is greatly underestimated in such regions. Furthermore, no association was observed between HTLV-I/II infection and SS, MF or pleomorphic cutaneous lymphoma in Mali in contrast to other studies.

Immune responses of specific-pathogen-free mice to chronic Helicobacter pylori (strain SS1) infection

A model permitting the establishment of persistent Helicobacter pylori infection in mice was recently described. To evaluate murine immune responses to H. pylori infection, specific-pathogen-free Swiss mice (n = 50) were intragastrically inoculated with 1.2 x 10(7) CFU of a mouse-adapted H. pylori isolate (strain SS1). Control animals (n = 10) received sterile broth medium alone. Animals were sacrificed at various times, from 3 days to 16 weeks postinoculation (p.i.). Quantitative culture of gastric tissue samples from inoculated mice demonstrated bacterial loads of 4.0 x 10(4) to 8 x 10(6) CFU per g of tissue in the animals. Infected mice had H. pylori-specific immunoglobulin M (IgM) and IgG antibodies in serum (at day 3 p.i.) and IgG and IgA antibodies in their gastric contents (weeks 4 and 16 p.i.) and saliva (week 16 p.i.). Mucosal IgM antibodies were not detected. Histological examination of the gastric mucosae from control and infected mice revealed mild chronic gastritis, characterized by the presence of polymorphoneutrophil cell infiltrates and submucosal lymphoid aggregates, in infected animals at 16 weeks p.i. Differences in the quantities of IgG1 and IgG2a subclass antibodies detected in the sera of mouse strains (Swiss, BALB/c, and C57BL/6) infected by H. pylori suggested that host factors influence the immune responses induced against this bacterium in the host. In conclusion, immune responses to H. pylori infection in mice, like those in chronically infected humans, appear to be ineffective in resolving the infection.

[Stomatococcus mucilaginosus infection. A rare cause of cutaneous histiocytic infiltrate]

We report the case of a systemic infection due to Stomatococcus mucilaginosus with cutaneous localisations occurring in a neutropenic child. The histological features of this cutaneous involvement are very unusual and the diagnosis can be suggested before bacteriological results.

Transferrin is an early marker of hepatic differentiation, and its expression correlates with the postnatal development of oligodendrocytes in mice

Transferrin (Tf), the iron transport protein, is essential for the growth and differentiation of cells. Therefore, it provides an excellent model to analyze the regulatory mechanisms controlling the expression of a eukaryotic gene in different cell types and during fetal and adult life. In this study, the tissue-specific and developmental regulation of the Tf gene in vivo were analyzed. Human Tf mRNA was detected mainly in fetal and adult liver. A weaker expression was observed in adult and fetal brain and in fetal spleen. By in situ hybridization the presence of mouse Tf mRNA was detected in the hepatic primordia. This is the first observation pointing out Tf as an early marker of hepatic differentiation, prior to the formation of the liver. Thus, TF may be an important tool to follow the hepatic specification of the gut endoderm. Mouse Tf mRNA was also detected in the liver bud and subsequently in the liver throughout fetal life, and in newborn and adult animals. No expression of the Tf gene was observed in the mouse fetal central nervous system (CNS). In contrast, Tf mRNA was detected from the 5th day after birth in the derivatives of the caudal part of the neural tube and subsequently in the derivatives of the rhomboencephalon and that of the prosencephalon. These results indicate that Tf gene expression correlates with the postnatal development of oligodendrocytes in the mouse CNS. To test whether the control elements of the human gene previously found in ex vivo experiments were also active in vivo during fetal and adult life, we fused the -4000/+395' flanking region of the human gene to the coding region of the lacZ gene and generated transgenic mice. The expression of the reporter gene during development was analyzed.

Molecular detection and characterization of yellow fever virus in blood and liver specimens of a non-vaccinated fatal human case

A yellow fever virus of a South American genotype was identified in the liver and blood samples of a non-vaccinated European patient after his return from Brazil. ELISA tests were negative for IgG and positive for IgM against yellow fever. Yellow fever proteins in the formalin-fixed and paraffin-embedded liver biopsy were detected by immunohistochemical procedures. Viral RNA extracted from the liver tissue was also detected using an RT-semi-nested PCR procedure and molecular hybridization. Alignment of the sequence obtained from a gene fragment amplified by RT-semi-nested PCR directly from a blood sample with those of African and South American yellow fever virus strains identified a Brazilian topotype as being responsible for the disease. RT-semi-nested PCR may be used advantageously for clinical specimens for rapid and specific diagnosis, and with archival biopsy material for retrospective studies.

Endotoxin induces expression of type II phospholipase A2 in macrophages during acute lung injury in guinea pigs: involvement of TNF-alpha in lipopolysaccharide-induced type II phospholipase A2 synthesis

Elevated levels of secretory type II phospholipase A2 (sPLA2-II) have been associated with a poor clinical outcome in the acute respiratory distress syndrome. This study identifies the cell source(s) and the mechanisms of sPLA2-II synthesis in the guinea pig model of acute respiratory distress syndrome induced by intratracheal injection of LPS. Administration of LPS led to an increase in lung membrane-associated calcium-dependent sPLA2 activity, which was abrogated by LY311727, a selective inhibitor of sPLA2-II. No sPLA2 activity was detected in the vascular compartment of the lung. LPS administration induced a parallel accumulation of sPLA2-II mRNA in lung tissues. In situ hybridization showed that sPLA2-II transcripts were synthesized in interstitial and alveolar macrophages (AM). Incubation of AM with LPS enhanced the expression of sPLA2-II mRNA, leading to stimulation of sPLA2-II synthesis and secretion. This increase was prevented by the addition of anti-TNF-alpha and anti-p55 TNF receptor Abs. Furthermore, the addition to AM of cellfree bronchoalveolar fluid collected from LPS-treated guinea pigs increased sPLA2-II expression, which was abrogated by anti-TNF-alpha Ab. These findings demonstrate that 1) macrophages are in vivo the major cell source of sPLA2-II in LPS-induced acute lung injury; 2) in contrast to that in other cell systems, regulation of LPS-induced sPLA2-II synthesis in AM is TNF-alpha dependent; and 3) production of TNF-alpha in the air-lung interface is an important step for sPLA2-II synthesis in macrophages.

Endotoxin induces expression of type II phospholipase A2 in macrophages during acute lung injury in guinea pigs: involvement of TNF-alpha in lipopolysaccharide-induced type II phospholipase A2 synthesis

Elevated levels of secretory type II phospholipase A2 (sPLA2-II) have been associated with a poor clinical outcome in the acute respiratory distress syndrome. This study identifies the cell source(s) and the mechanisms of sPLA2-II synthesis in the guinea pig model of acute respiratory distress syndrome induced by intratracheal injection of LPS. Administration of LPS led to an increase in lung membrane-associated calcium-dependent sPLA2 activity, which was abrogated by LY311727, a selective inhibitor of sPLA2-II. No sPLA2 activity was detected in the vascular compartment of the lung. LPS administration induced a parallel accumulation of sPLA2-II mRNA in lung tissues. In situ hybridization showed that sPLA2-II transcripts were synthesized in interstitial and alveolar macrophages (AM). Incubation of AM with LPS enhanced the expression of sPLA2-II mRNA, leading to stimulation of sPLA2-II synthesis and secretion. This increase was prevented by the addition of anti-TNF-alpha and anti-p55 TNF receptor Abs. Furthermore, the addition to AM of cellfree bronchoalveolar fluid collected from LPS-treated guinea pigs increased sPLA2-II expression, which was abrogated by anti-TNF-alpha Ab. These findings demonstrate that 1) macrophages are in vivo the major cell source of sPLA2-II in LPS-induced acute lung injury; 2) in contrast to that in other cell systems, regulation of LPS-induced sPLA2-II synthesis in AM is TNF-alpha dependent; and 3) production of TNF-alpha in the air-lung interface is an important step for sPLA2-II synthesis in macrophages.