Human alveolar macrophages produce leukotriene B4.

Abstract

Human alveolar macrophages obtained by bronchoalveolar lavage were labeled overnight with [3H]arachidonic acid. The cells were stimulated with calcium ionophore A23187, and the 20:4 oxygenated metabolites released into the culture medium were identified by reverse-phase HPLC. Leukotriene B4 was the major 20:4 metabolite produced by these cultures. Leukotriene B4 was identified by its reverse-phase HPLC elution time, its UV spectrum, and its chemotactic and chemokinetic activities for neutrophils. In addition, the macrophage. and neutrophil-derived leukotriene B4 free acids and methyl esters were found to have identical HPLC retention times.The leukotrienes are a recently discovered class of biologically active compounds that are formed from arachidonic acid (20:4) via the lipoxygenase pathway. They include leukotriene B4 [LTB4, (5S, 12R) dihydroxy-6, 14-cis-8, 10-trans-icosatetraenoic acid] (1), a compound with multiple proinflammatory actions, including chemotactic activity for neutrophils (2), and the slowreacting substances, leukotrienes C4 [(5S)-hydroxy-(6R)-S-glutathionyl-7,9-trans-11, 14-cis-icosatetraenoic acid] and D4 [(5S)-hydroxy-(6R)-S-cysteinylglycine -7,9-trans-11, 14 -cis-icosatetraenoic acid] (3, 4), which have vasoactive properties in addition to their contractile activity on select smooth muscle.All major classes ofgranulocytes have been shown to produce leukotrienes in vitro. However, recent studies with murine pulmonary and peritoneal macrophages indicated that macrophages may be a particularly rich source of these compounds, with LTC4 being the major lipoxygenase product (5, 6). To date, the macrophage is the only cell type known to synthesize substantial quantities of leukotrienes in response to inflammatory stimuli such as zymosan (5), and IgG (7) and IgE (8) immune complexes.In this paper, we report the capacity of human alveolar macrophages to produce leukotrienes. Pulmonary alveolar macrophages represent a large population of resident leukocytes in the lung and as such are believed to be the first line of defense against inhaled material. These cells therefore are ideally positioned to initiate inflammatory and allergic reactions in the lung. The available evidence suggests that human alveolar macrophages generate a low molecular weight chemotactic factor for neutrophils that may be a lipid (9). Our work identifies one such molecule and demonstrates that LTB4 is the major lipoxygenase product of these cells when they are stimulated with calcium ionophore A23187. MATERIALS AND METHODSIsolation of Human Alveolar Macrophages. Human alveolar macrophages were obtained by fiberoptic bronchoscopy with bronchoalveolar lavage in patients who had given informed consent. Lidocaine (2%) was used to anesthetize the nose and upper airways. The bronchoscope (model FB-19D, Pentex Precision Instrument, Norwood, NJ) was then passed transnasally and wedged into a subsegmental bronchus of the right middle lobe or lingula. Lidocaine (1%) was used as needed to suppress cough. Sterile saline, 100 to 1...

Bronchial inflammation in acute bacterial exacerbations of chronic bronchitis: the role of leukotriene B4

“…The source of the LTB 4 is uncertain and may reflect contributions from resident macrophages and epithelial cells [26,27] as well as activated neutrophils themselves [28]. The LTB 4 concentrations correlated with both the overall chemotactic activity (r=0.76) and the contribution of LTB 4 to the chemotactic activity, as assessed by its reduction in the presence of the specific LTB 4 receptor antagonist (r=0.69).…”

Specific leukotriene formation by purified human eosinophils and neutrophils

“…Several types of human blood and tissue cell e.g., granulocytes [1,2], lymphocytes [3], macrophages [4,5] and mast cells [6], are capable of synthesizing leukotrienes from arachidonic acid. Leukotriene C4 (LTC4: S(S)-hydroxy-6(R)-S-glutathionyl-7,9trans-11,14-cis-eicosatetraenoic acid) and leukotriene D4 (LTD4: 5(S)-hydroxy-6(R)-Scysteinylglycyl-7,9-trans-11,14-cl,.+eicosatetraenoic acid) have been shown to be strongly bronchoconstrictive in vitro [7] as well as in vivo [S] and therefore may play an important role as mediators in (immediate) hypersensitivity reactions.…”

Zanvil Alexander Cohn 1926-1993.

“…This glutathione-lipid adduct was otherwise known as one of the trace "slow reacting substances" that cause spasms of airway smooth muscle. They noted that mouse pulmonary macrophages synthesized leukotrienes C, D, and E (211), while human alveolar macrophages made substantial amounts of the chemotactic agent leukotriene B4 (202). Rouzer, Scott, and Cohn discovered that the release of LTC from macrophages could be triggered by IgE-antiIgE complexes (210,212), a remarkable finding considering the prior emphasis that IgE immune complexes worked primarily on mast cells.…”

“…This work went beyond a new nomenclature to a redefinition based on developmental origins and cell biological features. Mononuclear phagocytes in other microenvironments were denoted and would attract Zan's attention later, for example, macrophages in the lung (202,211,277,302), liver (256,257), and spleen (328). Once cell biological criteria had been brought to the identification of mononuclear phagocytes, the foundation was in place for the laboratory to pursue other distinct cell systems, especially endothelial cells and dendritic cells.…”