Heterogeneity of Procoagulant Activity and Cytokine Release in Subpopulations of Alveolar Macrophages and Monocytes

We have studied the expression of tissue factor (TF) and fibrinopeptide A (FPA) generation as well as the release capacity of TNF-, IL-1, and IL-6 in density-defined subpopulations of alveolar macrophages (AM) and monocytes (Mo). TF was equally expressed on all AM subpopulations and Mo, while the FPA-forming capacity was at the same level in low density AM as in Mo and was significantly (P < 0.05) higher in low density AM than in high density AM. The lipopolysaccharide (LPS)-induced release of TNF- was higher (P < 0.05) in high density AM than in low density AM and in Mo. IL-1 release was undetectable in unstimulated AM and in LPS-stimulated low density AM, while the LPS-induced IL-1 release in high density AM was low compared to the levels demonstrated in Mo. LPS-stimulated IL-6 release was not distinctively different in the AM subpopulations and Mo. The presented study showed that FPA generation and LPS-stimulated TNF- release were dependent on the density (i.e., maturity) of AM. This implies that a skewed distribution of AM subpopulations induced by disease processes may profoundly influence the inflammatory reactions, including extravascular activation of coagulation.     

Interaction of Alveolar Macrophages with Nocardia asteroides: Immunological Enhancement of Phagocytosis, Phagosome-Lysosome Fusion, and Microbicidal Activity

Normal and specifically activated rabbit alveolar macrophages were infected in vitro with Nocardia asteroides GUH-2. In the presence of serum from normal rabbits, no significant differences were noted between normal and activated alveolar macrophages with respect to phagocytosis, incidence of phagosomelysosome fusion, or nocardicidal activity. However, all of these macrophage functions were enhanced by various immunological components. Serum from immunized rabbits enhanced phagocytosis of nocardial cells by activated macrophages, and there was an additional increase in phagocytosis observed when alveolar lining material was present. Complement had no effect on the ability of the macrophages to phagocytize nocardial cells. The greatest percentage of organisms phagocytized was observed when specifically primed lymph node cells, alveolar lining material, and serum from immunized rabbits were present in the incubation medium. N. asteroides GUH-2 inhibited phagosome-lysosome fusion in normal macrophages in the presence of serum from normal rabbits. However, addition of serum from immunized rabbits or the addition of specifically primed lymphocytes increased the amount of phagosome-lysosome fusion, whereas complement had no effect on this fusion process. Nocardial viability was not reduced when either normal or activated macrophages were infected with bacteria in the presence of normal serum, immune serum, or alveolar lining material. However, specifically activated macrophages incubated with primed lymph node cells obtained from immunized rabbits were able to both decrease the number of viable organisms recovered and to increase the incidence and extent of bacterial cell damage. The greatest number of organisms were killed by specifically activated macrophages when the bacterial cells were incubated with primed lymph node cells suspended in immune serum and alveolar lining material. These results indicate that activated macrophages alone are not sufficient to kill ingested N. asteroides GUH-2 and that specifically primed lymphocytes are important in host resistance to nocardial infections.     

Epigallocatechin gallate,a potential immunomodulatory agent of tea components,diminishes cigarette smoke condensate-induced suppression of anti-Legionella pneumophila activity and cytokine responses of alveolar macrophages

Even though cigarette smoking has been shown to suppress immune responses in the lungs, little is known about the effect of cigarette smoke components on respiratory infections. In the present study, the effects of cigarette smoke condensate (CSC) on bacterial replication in alveolar macrophages and the immune responses of macrophages to infection were examined. Furthermore, a possible immunotherapeutic effect of epigallocatechin gallate (EGCg), a major form of tea catechins, on the CSC-induced suppression of antimicrobial activity and immune responses of alveolar macrophages was also determined. The treatment of murine alveolar macrophage cell line (MH-S) cells with CSC significantly enhanced the replication of Legionella pneumophila in macrophages and selectively down-regulated the production of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) induced by bacterial infection. The treatment of macrophages with EGCg not only overcame the CSC-induced suppression of antimicrobial activity but also strengthened the resistance of macrophages to infection. EGCg also markedly up-regulated the CSC-suppressed IL-6 and TNF-alpha production by macrophages in response to infection. The results of exogenous TNF-alpha treatment and neutralization treatment with anti-TNF-alpha and anti-gamma-interferon (IFN-gamma) antibodies and the determination of IFN-gamma mRNA levels indicate that CSC-suppressed macrophages can be activated by EGCg to inhibit L. pneumophila growth by up-regulation of TNF-alpha and IFN-gamma production. Thus, this study revealed that CSC selectively alters the immune responses of macrophages to L. pneumophila infection and leads to an enhancement of bacterial replication in macrophages. In addition, the tea catechin EGCg can diminish such suppressive effects of CSC on alveolar macrophages.     

Evidence that C1q,a Subcomponent of the First Component of Complement,is an Fc Receptor of Peritoneal and Alveolar Macrophages

Guinea pig peritoneal macrophages were cultured for 24 h in the presence of two inhibitors of the biosynthesis of collagen-like molecules such as C1q : 10^-3 M 3,4-dehydroproline or 10^-4 M 2,2′-dipyridyl. Their Fc-receptor activity was measured by rosette formation, using sheep erythrocytes (E) coated with rabbit anti-sheep IgG (EA_IgG). The Fc-receptor activity was decreased by 40 to 70% of control cultures depending on the amount of IgG on the E. The activity of a second receptor on the macrophages, mediating the binding of C3b coated E, was not altered by this treatment.Rat alveolar macrophages were depleted of their Fc-receptor activity by pronase treatment (1.5 mg/ml) in the presence of 2,2′-dipyridyl. After washing the cells, the EA_IgG-binding activity was restored to about half of the initial level within 2 h. With 2,2′-dipyridyl also present during the second incubation, the re-expression of the Fc-receptor activity was suppressed further.Preincubation of guinea pig peritoneal macrophages with anti-C1q-F(ab')₂ for 45 min at 37°C caused a dose-dependent reduction of the Fc-receptor activity, but not C3b receptor activity.These results support our hypothesis that C1q synthesized and secreted by macrophages serves as an Fc-receptor in the membrane during the secretion.     

Immunotherapy Suppresses both Th1 and Th2 Responses by Allergen Stimulation, but Suppression of the Th2 Response is a More Important Mechanism Related to the Clinical Efficacy of Immunotherapy for Perennial Allergic Rhinitis

Increased attention has recently been directed at the possibility that the clinical efficacy of immunotherapy might be elaborated by alteration of T-cell reactivity. However, there is no general agreement among different investigators regarding the effect of immunotherapy on Th-cell reactivity. Peripheral blood mononuclear cells (PBMCs) from 15 nonatopic subjects and 76 patients with perennial allergic rhinitis (18 untreated patients and 58 patients on immunotherapy) were cultured in the absence and in the presence of a major Dermatophagoides farinae allergen, Der f 1, and the levels of IgE, interleukin-5 (IL-5), interferon-gamma (IFN-γ) and tumor necrosis factor-α (TNF-α) in the culture supernatants were determined. The difference between the absence and presence of Der f 1 was calculated to consider the Der f 1-dependent synthesis of IgE, IL-5, IFN-γ and TNF-α. The levels of Der f 1-dependent synthesis of IgE, IL-5 and TNF-α were significantly higher in the untreated group than in the nonatopic group, whereas Der f 1-dependent synthesis of IFN-γ was significantly lower in the untreated group than in the nonatopic group. Immunotherapy decreased the enhanced Der f 1-dependent synthesis of IgE, IL-5 and TNF-α, and further decreased the suppressed Der f 1-dependent synthesis of IFN-γ as the therapy proceeded. The levels of Der f 1-dependent synthesis of IgE and IL-5 did not differ between nonatopic individuals and patients whose duration of immunotherapy was 10 or more years. The levels of Der f 1-dependent synthesis of IgE and IL-5, but not of IFN-γ and TNF-α, were correlated significantly with the levels of symptom scores. In addition, the levels of Der f 1-dependent synthesis of IgE and IL-5, but not of IFN-γ and TNF-α, differed significantly between good and poor responders. In conclusion, immunotherapy for perennial allergic rhinitis may possibly work via induction of tolerance or anergy of both Th1- and Th2 cells. However, our study is likely to support a view that the mechanisms responsible for the clinically beneficial effects of immunotherapy principally involve the tolerance of Th2- rather than Th1 cells. In addition, suppression of IgE synthesis is also likely to be linked to the clinical efficacy of immunotherapy for perennial allergic rhinitis.