leukotriene-b4 and Pneumonia--Pneumocystis

Human immunodeficiency virus (HIV)-infected patients are at increased risk of contracting bacterial infections, mainly pneumonia. Despite this, little is known about immunopathogenic mechanisms in HIV-related bacterial pneumonia. This paper investigates the presence of the neutrophil chemotactic mediators, interleukin-8 (IL_8) and leukotriene B4 (LTB4), in bronchoalveolar lavage (BAL) fluid from 27 HIV-infected patients with bacterial pneumonia. Significantly elevated levels of IL-8 were found in BAL fluid of patients with bacterial pneumonia [529 pg ml-1 (296-1161 pg ml-1)] compared to matched patients with Pneumocystis carinii pneumonia (PCP) [59 pg ml-1 (42-254 pg ml-1)] and healthy controls [58 pg ml-1 (37-82 pg ml-1)]. Levels of LTB4 were not elevated during bacterial pneumonia when compared to PCP patients and healthy controls. Furthermore, a positive correlation was found between IL-8 levels in BAL fluid and relative BAL neutrophilia (r = 0.60, P = 0.001) in bacterial pneumonia. In conclusion, elevated IL-8 levels in BAL fluid were found in patients suffering from bacterial pneumonia, which may account for the influx of neutrophils to the lung, whereas LTB4 appears not to be an important chemotactic factor in this setting.

Topics: Bronchoalveolar Lavage Fluid; CD4 Lymphocyte Count; Chemotaxis, Leukocyte; Haemophilus Infections; HIV Infections; Humans; Interleukin-8; Leukotriene B4; Neutrophils; Pneumococcal Infections; Pneumonia, Bacterial; Pneumonia, Pneumocystis; Staphylococcal Infections

Pneumocystis carinii pneumonia (PCP) is accompanied by an acute inflammatory infiltration of the lung parenchyma. The cellular infiltrate is characterized by inflammatory cells including neutrophils, lymphocytes and macrophages. Furthermore, neutrophilia in bronchoalveolar lavage (BAL) fluid has been shown to confer a poor prognosis in PCP. We therefore investigated the potential of BAL fluid from 17 patients with PCP to induce neutrophil chemotaxis. BAL fluid from patients induced considerable neutrophil chemotactic activity compared to normal controls. Elevated levels of IL-8 were detected in patient samples as compared to controls. A specific anti-IL-8 antibody significantly reduced chemotactic activity of patient samples by more than 50%. In conclusion, IL-8 appears to be a significant participant of neutrophil chemotaxis in AIDS-associated PCP, and may participate in the recruitment of neutrophils to the lung during PCP.

Topics: Adult; AIDS-Related Opportunistic Infections; Antibodies, Blocking; Bronchoalveolar Lavage Fluid; CD4 Lymphocyte Count; Chemotaxis; Humans; Interleukin-8; Leukotriene B4; Middle Aged; Neutrophils; Pneumonia, Pneumocystis; Recombinant Proteins

Pneumocystis carinii is an opportunistic organism that causes severe lung injury in immunocompromised hosts. Macrophage responses to P. carinii are poorly defined. Arachidonic acid (AA) and its metabolites are potent mediators of inflammation and have been implicated in host response to microorganisms. We therefore examined the production of eicosanoids from rat and rabbit alveolar macrophages stimulated with purified P. carinii. [14C]AA-labeled rabbit macrophages released 8.50 +/- 1.33% of the incorporated [14C]AA after 90 min in response to P. carinii (P = 0.0001 compared with unstimulated controls). In contrast, a similar number of rat alveolar macrophages exhibited a smaller but significant response to P. carinii, releasing 3.84 +/- 1.54% of their [14C]AA after 90 min (P = 0.001 compared with control). We further determined that P. carinii stimulated substantial production of prostaglandin E2 and concurrently a small amount of leukotriene B4 release from alveolar macrophages. To further investigate whether serum opsonization of P. carinii enhances these alterations in AA metabolism, we assessed the effect of P. carinii immune serum on P. carinii-induced AA release. P. carinii opsonized with this antiserum caused significantly greater AA release from rat alveolar macrophages than either unopsonized P. carinii or organisms opsonized with nonimmune serum. Previous studies suggest that P. carinii interacts with macrophage beta-glucan and mannose receptors. However, incubation of macrophages with P. carinii in the presence of either soluble beta-glucan or alpha-mannan failed to alter the release of AA from macrophages in response to P. carinii. Macrophage release of eicosanoids represents a potentially important host inflammatory response to P. carinii infection.

Topics: Animals; Arachidonic Acids; Dinoprostone; Female; Glucans; Lectins, C-Type; Leukotriene B4; Macrophages, Alveolar; Mannose; Mannose Receptor; Mannose-Binding Lectins; Opsonin Proteins; Phagocytosis; Pneumocystis; Pneumonia, Pneumocystis; Rabbits; Rats; Rats, Sprague-Dawley; Receptors, Cell Surface; Receptors, Immunologic; Solubility

To investigate the pathogenesis of lung injury in Pneumocystic carinii pneumonia and nonspecific interstitial pneumonitis (NIP), common pulmonary complications of human immunodeficiency virus (HIV) infection. The efficacy of corticosteroid therapy in P carinii pneumonia and the observation that bronchoalveolar lavage (BAL) neutrophilia predicts a poor prognosis support the premise that the lung injury of P carinii pneumonia is due to the host's inflammatory response to the infection.. In vitro measurements on previously collected BAL fluid samples.. The Clinical Center of the National Institutes of Health, a research hospital and tertiary care referral center.. Five normal volunteers, 5 asymptomatic HIV-positive patients, 10 HIV-positive patients with NIP (5 asymptomatic and 5 with respiratory symptoms), and 19 HIV-positive patients with P carinii pneumonia.. BAL leukotriene B4 (LTB4), interleukin 8 (IL-8), and phospholipase A2 (PLA2) were measured. IL-8 and PLA2 were elevated in patients with P carinii pneumonia, and IL-8 correlated with BAL fluid absolute neutrophil count. LTB4, IL-8, and PLA2 levels were elevated in patients with NIP; LTB4 and PLA2 levels correlated with absolute neutrophil count, and IL-8 correlated with alveolar-arterial oxygen pressure difference. IL-8 was elevated in the asymptomatic HIV-positive patients, and there was a trend toward elevation of PLA2 in this group.. IL-8 appears to play a role in the pathogenesis of lung injury in P carinii pneumonia and may be the principal neutrophil chemotaxin in this disease; PLA2 may also be involved in the pathogenesis of P carinii pneumonia. Both LTB4 and IL-8 may be involved in the recruitment of neutrophils and subsequent lung injury of NIP. These data suggest that there are varying mechanisms by which inflammatory cells are recruited to the lung in different HIV-related lung diseases.

Topics: Adult; AIDS-Related Opportunistic Infections; Bronchoalveolar Lavage Fluid; Chromatography, High Pressure Liquid; Female; HIV Infections; HIV Seropositivity; Humans; Interleukin-8; Leukotriene B4; Lung Diseases; Male; Middle Aged; Phospholipases A; Phospholipases A2; Pneumonia, Pneumocystis; Pulmonary Fibrosis