Aspirin augments IgE-mediated histamine release from human peripheral basophils via Syk kinase activation.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs), especially aspirin, and food additives (FAs) may exacerbate allergic symptoms in patients with chronic idiopathic urticaria and food-dependent exercise-induced anaphylaxis (FDEIA). Augmentation of histamine release from human mast cells and basophils by those substances is speculated to be the cause of exacerbated allergic symptoms. We sought to investigate the mechanism of action of aspirin on IgE-mediated histamine release. METHODS: The effects of NSAIDs, FAs or cyclooxygenase (COX) inhibitors on histamine release from human basophils concentrated by gravity separation were evaluated. RESULTS: Benzoate and tartrazine, which have no COX inhibitory activity, augmented histamine release from basophils similar to aspirin. In contrast, ibuprofen, meloxicam, FR122047 and NS-398, which have COX inhibitory activity, did not affect histamine release. These results indicate that the augmentation of histamine release by aspirin is not due to COX inhibition. It was observed that aspirin augmented histamine release from human basophils only when specifically activated by anti-IgE antibodies, but not by A23187 or formyl-methionyl-leucyl-phenylalanine. When the IgE receptor signaling pathway was activated, aspirin increased the phosphorylation of Syk. Moreover, patients with chronic urticaria and FDEIA tended to be more sensitive to aspirin as regards the augmentation of histamine release, compared with healthy controls. CONCLUSIONS: Aspirin enhanced histamine release from basophils via increased Syk kinase activation, and that the augmentation of histamine release by NSAIDs or FAs may be one possible cause of worsening symptoms in patients with chronic urticaria and FDEIA.

[In vitro anti-tumor effect of cytotoxic T lymphocyte activated by antigen- loaded dendritic cells from peripheral blood mononuclear cells treated with calcium ionophore A23187 and GM-CSF].

OBJECTIVE: To evaluate the effect of calcium ionophore (CI) A23187 and human recombinant granulocyte/macrophage colony stimulating factor (rhGM-CSF) on the cultivation of dendritic cell (DC) from healthy human peripheral blood mononuclear cell (PBMC) and to evaluate the in vitro effect of DC stimulated by K562 cell lysate on inducing specific cytotoxic T lymphocyte (CTL) against K562 cell. METHODS: Human PBMCs isolated from healthy subjects were separated into two groups. In Group A, the cells were cultured with additional rhGM-CSF, recombinant human interleukin 4 and recombinant human tumor necrosis factor-α only as control group. In Group B, the cells were cultured in the presence of rhGM-CSF and CI A23187. The cells in both groups were pre-incubated with K562 cell lysate at 37°C for 30 min. The cells were harvested after a 4-day cultivation. Morphology of DC was continuously observed under inverted microscope. The surface antigens of induced cells were analyzed by flow cytometry (FCM). Then the proliferation of allogeneic T cell and the specific cytotoxicity of T cell primed with DC were examined by colorimetry. Also, the nonspecific inhibition of DC loaded K562 cell lysate against K562 cell was detected. RESULTS: Typical morphological features of DC could be observed in both groups. The expressions of CD83, CD1a, CD86 and CD40 were stronger in Group B than those in control group (45.2% ± 1.8%, 31.5% ± 3.9%, 40.1% ± 7.8%, 36.4% ± 6.3% vs 16.9% ± 1.3%, 20.4% ± 3.4%, 26.5% ± 2.2%, 22.3% ± 3.0%) (all P < 0.05). The expression of CD14 was weaker in Group B than that in control group (5.7% ± 0.8% vs 19.0% ± 1.6%) (P < 0.05). As compared with the control group, DC in Group B loaded with K562 lysate could evidently stimulate the proliferation of allogeneic T cell (P < 0.05, exclusion of effector-to-target ratio of 1:40) and inhibit the growth of K562 cell (P < 0.05). In addition, both groups of DC-stimulated CTL had specific cytotoxicity against K562 cell. At the effector-to-target ratios of 10:1 and 40:1, the DC-stimulated CTL of Group B had stronger cytotoxicity against K562 cell (both P < 0.05). CONCLUSION: In combination with rhGM-CSF, CI A23187 induces PBMC into DC in a more effective way. DC loaded with K562 lysate can stimulate CTL and maintain high immunocompetence with specific cytotoxicity against K562 cell.

Xanthone suppresses allergic contact dermatitis in vitro and in vivo.

Xanthone is a phenolic compound found in a few higher plant families; it has a variety of biological activities, including antioxidant, anti-inflammatory, and anticancer properties. However, the molecular and cellular mechanisms underlying the activity of xanthone in allergic contact dermatitis (ACD) remain to be explored. Therefore, this study aimed to investigate the regulatory effects of xanthone in ACD in human keratinocytes (HaCaT cell), and human mast cell line (HMC-1 cell) in vitro and in an experimental murine model. The results demonstrated that treatment with xanthone reduced the production of pro-inflammatory cytokines and chemokines including interleukin (IL)-1ß, IL-6, IL-8, and expression of chemokines thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in tumor necrosis factor (TNF)-α and interferon (IFN)-γ-stimulated HaCaT cells. Xanthone also suppressed the production of pro-inflammatory cytokines, chemokines, and allergic mediators in phorbol myristate acetate/A23187 calcium ionophore (PMACI)-stimulated HMC-1 cells. Xanthone significantly suppressed the phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) and activation of caspase-1 signaling pathway in vitro model. Additionally, xanthone administration alleviated 2,4-dinitrofluorobenzene (DNFB)-induced atopic dermatitis like-skin lesion by reducing the serum levels of immunoglobulin E (IgE), histamine, and pro-inflammatory cytokines and suppressing MAPKs phosphorylation. Xanthone administration also inhibited mortality due to compound 48/80-induced anaphylactic shock and suppressed the passive cutaneous anaphylaxis (PCA) reaction mediated by IgE. Collectively, these results suggest that xanthone has a potential for use in the treatment of allergic inflammatory diseases.

[Research on A23187 inducing HL-60 cells to differentiate into dendritic cells].

OBJECTIVE: To investigate the method for calcium mobilization inducing rapidly to produce the dendritic cells (DC) from myeloid leukemia cells. METHODS: HL-60 cells were cultured with calcium ionophore A23187 (45-720 ng/mL) or plus rhIFN-gamma (1000 U/mL) for 20-96 hours. The morphologic features of cells were observed under inverted microscope and scanning electron microscope, when the cell phenotypes of HL-60 treated with A23187 were determined by flow cytometry. The proliferation of allogeneic human T cells was tested by mixed lymphocyte reaction (Allo-MLR). RESULTS: After treated with A23187 (180 ng/mL) or plus rhIFN-gamma (1000 U/mL) for 20 hours, some of HL-60 cells were found to have the dendritic appearance on cell surface; and the CD83 as a characteristic marker of mature DCs, co-stimulating molecules CD80 and CD86 got an up-regulated expression. When HL-60 cells were cultured with A23187 for 48 hours, the expression of CD83 began going down. A large number of cells with typical dendritic appearance were observed after cultured with A23187 for 72 hours, and the expressions of CD80 and CD86 were up-regulated continuously. Allo-MLR revealed that DCs derived from HL-60 cells treated with A23187 or plus rhIFN-gamma could stimulate the proliferation of allogeneic human T cells. CONCLUSION: The calcium ionophore A23187 can induce the HL-60 cells into mature DCs. This study suggests that calcium mobilization for cell differentiation may be an alternative way to rapidly acquire DCs.

Activation of channel catfish (Ictalurus punctatus) T cells involves NFAT-like transcription factors.

Cyclosporin A (CsA) specifically inhibits mammalian T cells by preventing activation of transcription factors (termed nuclear factor of activated T cells (NFAT)) involved in cytokine gene expression. In this study, catfish peripheral blood lymphocytes (PBL) and antigen specific T cells were treated with CsA to gain insights into the intracellular processes involved in fish T cell activation. To this end, CsA was observed to inhibit the in vitro proliferation of Con A stimulated catfish PBL, and specific alloantigen stimulated T cells. However, the inhibitory effect of CsA on catfish T cells was obviated by treatment with Con A, antigen activation or culture supernatant from activated catfish T cells prior to the addition of CsA. The use of a phosphatase assay coupled with Western blot analysis employing a polyclonal antibody to mammalian NFAT indicated that CsA prevents the dephosphorylation and subsequent nuclear translocation of an NFAT-like molecule in catfish T cells. Finally, a nuclear protein selection protocol demonstrated that a catfish NFAT-like protein binds to a known murine IL-2 promoter sequence. These results suggest that cytokines are involved in the activation of teleost T cells, and argue that T cell activation processes are conserved over a wide phylogenetic distance.

Development of a novel scintillation proximity radioimmunoassay for platelet-activating factor measurement: comparison with bioassay and GC/MS techniques.

A novel, facile and sensitive scintillation proximity radioimmunoassay (SPRIA) for quantitation of PAF has been developed. No separation of antibody bound [3H]PAF from free [3H]PAF is required as the assay employs protein A - coated fluomicrospheres (beads containing scintillant). The assay system was suitable for the quantitation of 0.03 to 2 pmol of 1-hexadecyl-2-acetyl-sn-glycero-3- phosphocholine. The cross-reactivity was high with 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine but was very low with PAF analogs such as 1-alkyl- and 1-acyl-2-lyso-sn-glycero-3-phosphocholine, 1-acyl-2-acetyl-sn-glycero-3-phosphocholine, and 1-alk-1'-enyl-2-acetyl-sn-glycero-3-phosphocholine. The specificity of SPRIA was higher than that of bioassay (platelet degranulation assay). PAF receptor antagonists (L-652,731, WEB2086, and FR900452) at up to 10 nmol per tube had no affect on the SPRIA. These observations indicate that the specificity of the PAF antibody is quite different from that of the platelet receptor. The values obtained using SPRIA for the measurement of PAF produced in polymorphonuclear leukocytes with stimuli are comparable to those obtained by SIM/GC/MS analysis.

Effect of costimulants on interleukin-2-like activities from goat peripheral blood mononuclear cells.

Culture supernatants containing interleukin-2-like activities (CS-IL2) were prepared from goat peripheral blood cells (mononuclear cells 75% and polymorphonuclear cells 25%). These were stimulated with three costimulants, (tetradecanoyl phorbol acetate, indomethacin and calcium ionophore A23187), either alone or in different combinations, in RPMI-1640 medium (containing 0.5% bovine serum albumin (BSA)) with or without serum. After 18 h of incubation with costimulants, concanavalin A (Con A) was added and the incubation was continued for next 48 h. Higher interleukin-2 (IL-2)-like activities were generated in the culture supernatants prepared in RPMI-1640 growth medium containing 0.5% BSA without serum. Further, IL-2-like activities were much higher in culture supernatants obtained by stimulation with all the three costimulants, as well as Con A, than the two costimulants with Con A or any of the costimulants with Con A.

Canine cutaneous mast cells dispersion and histamine secretory characterization.

In view of the high incidence of canine cutaneous atopic disease and the relevance of mast cells to its pathogenesis, it was considered important to isolate firstly cutaneous mast cells from normal dog skin and to assess the histamine secretory activity, as this can be further used as a tool for the study of canine skin mast cell pharmacology in cutaneous atopy. The procedure for canine dermal mast cell dispersion following a skin enzymatic digestion (as for previous human skin mast cell dispersion methods) is described in detail. The number of canine cutaneous mast cells yielded per gram of skin was 2.31 +/- 0.21 x 10(5) representing 1.00% of the total cutaneous cells. The total histamine content per mast cell is 4.93 +/- 0.39 pg. Net histamine release owing to stimulation by calcium ionophore A23187 (1 microM) and concanavalin A (1 mg ml-1) was respectively 32.17 +/- 3.56% and 20.39 +/- 2.41% of the total amount per cell. Viability and reactivity to both stimuli of dispersed cutaneous mast cells were similar to the results found in humans. The present study allows further research on the role of mast cells immunopharmacology in allergy by investigation of cells isolated from canine skin in naturally occurring or experimentally induced atopy in the dog to be undertaken.

Atypical mechanisms regulate the PMA-induced expression of IFN-gamma in a porcine trophectoderm cell line.

Interferon-gamma (IFN-gamma) is a major effector cytokine of the immune system with an expression pattern strictly restricted to cells of the lymphoid lineage. Several years ago, we reported that, during early pregnancy, the trophectoderm of the pig blastocyst, which represents a monolayer of polarized epithelial cells secretes high amount of IFN-gamma in a transient and developmentally regulated manner. In an effort to study the molecular basis of this atypical IFN-gamma gene expression, a pig trophectoderm cell line, TBA B4-3, was established in our laboratory. These cells developed a polarized phenotype with high transepithelial electrical resistance (TER) when grown on a microporous membrane. We found that treatment of polarized TBA B4-3 cells with the strong PKC agonist PMA induced, 3-4 days later, a transient IFN-gamma mRNA expression and vectorial IFN-gamma protein secretion. In order to better understand IFN-gamma gene regulation in TBA B4-3 cells, we examined in this system the effect of several drugs and factors known to affect the inducibility of this cytokine in T lymphocytes, the main source of IFN-gamma in the immunocompetent animal. We found that cyclosporine A (CsA) treatment of TBA B4-3 cells induces a partial inhibition of IFN-gamma secretion, thus indicating a minor role for the calcineurin signaling pathway in IFN-gamma expression. In addition, we found that although PMA alone can induce IFN-gamma secretion, the calcium ionophore A23187 synergizes with PMA for induction. We also analyzed by Southern blot the methylation status of a CpG dinucleotide in the 5' flanking region of IFN-gamma promoter and found that it was unmethylated in TBA B4-3 cells and in several pig epithelial cell lines that do not express IFN-gamma thus indicating the absence of correlation between demethylation and the ability to express IFN-gamma. Taken together, these results indicate that the mechanisms involved in IFN-gamma induction in TBA B4-3 cells are atypical compared to those presently known to operate in the T cell lineage.

Evaluation of leukotriene biosynthetic capacity in lung tissues from horses with recurrent airway obstruction.

OBJECTIVE: To evaluate leukotriene (LT) biosynthetic capacity in lung tissue from healthy horses and horses with recurrent airway obstruction (RAO). SAMPLE POPULATION: Lung parenchyma and airway specimens from 8 RAO-affected and 5 healthy horses. PROCEDURE: Horses were stabled for > or = 72 hours. Blood was drawn before euthanasia, after which lung specimens were collected. Tissue strips from small airways and parenchyma were incubated in organ baths with the precursor LTA4 or stimulated with calcium ionophore A23187 or the tripeptide N-formyl-Met-Leu-Phe (fMLP), with or without exogenous arachidonic acid, in the presence of isolated blood neutrophils. RESULTS: Stabling induced typical clinical signs of airway obstruction in RAO-affected horses but not control horses. When lung parenchyma or airway specimens from both groups of horses were incubated with calcium ionophore, with or without arachidonic acid, they did not form LT. In contrast, addition of LTA4 to both tissues resulted in conversion to LTB4, although concentrations of LTC4 were negligible in airways and parenchymal strips from healthy and RAO-affected horses. Incubation of airway and parenchymal strips with suspensions of autologous neutrophils did not influence formation of LT stimulated by calcium ionophore or fMLP, with or without exogenous arachidonic acid. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that lung parenchyma and airway tissues themselves are not of substantial importance for LT formation in the lungs, although these tissues possessed some LTA4 hydrolase activity, enabling LTB4 formation. It may be speculated that LTB4 originates primarily from neutrophils and may play a role in the inflammatory events of RAO.

In vitro allergen-induced degranulation of pulmonary mast cells from horses with recurrent airway obstruction (heaves).

OBJECTIVE: To determine the capacity of pulmonary mast cells (PMC) to degranulate in response to various potential allergens and other secretagogues in horses with recurrent airway obstruction (heaves) and clinically normal horses before and after exposure to moldy hay. ANIMALS: 5 horses with heaves and 5 clinically normal horses. PROCEDURES: Heaves was characterized as an increased clinical respiratory score and maximum change in transpulmonary pressure of > 20 cm H2O after exposure. Bronchoalveolar lavage was performed during each period. Washed and resuspended cells were exposed for 20 minutes at 37 C with whole reconstituted freeze-dried preparations of Aspergillus fumigatus, Alternaria tenuis, and Ambrosia elatior, fungal extracts of Aspergillus fumigatus, Alternaria tenuis, and Micropolyspora faeni; A23187; and compound 48/80. Histamine release (HR) was used as a marker of degranulation. RESULTS: Compared with clinically normal horses, HR was significantly greater from PMC from horses with heaves during remission and exacerbation in response to whole preparations and extracts of Aspergillus fumigatus and whole preparations of Alternaria tenuis. Extracts of Alternaria tenuis caused significantly greater HR from PMC from horses with heaves during exacerbation. Histamine was also released from PMC in response to A23187 and to changes in osmolality of the medium, but only as a result of cell lysis by compound 48/80. CONCLUSIONS: Increased degranulation of PMC after antigenic challenge may contribute to the pathogenesis of heaves in horses. CLINICAL RELEVANCE: Strategies for prevention and treatment that attenuate degranulation of PMC may assist in the clinical management of horses with heaves.

Histamine release and morphological changes in basophilic granulocytes of atopic asthmatics induced by antigen, anti-IgE and Ca ionophore A 23187.

Morphological changes of basophils from atopic asthmatics were compared among antigen, anti-IgE and Ca ionophore A23187 stimulation. 1. Antigen induced rapid and marked increase of histamine release from basophils compared with Ca ionophore A23187. 2. The decrease in number of basophils following stimulation with the agents was significantly higher in antigen stimulation than in Ca ionophore A23187 stimulation. 3. The increased ratio of short to long axis diameter (L/Sb ratio) of the cells, which shows an increased motility of basophils, was significantly higher in antigen stimulation. The ratio did not change by stimulation with Ca ionophore A23187. 4. Stimulation of basophils by Ca ionophore A23187 induced marked increase in mean diameter (MD) of the cells. Activation of basophils by anti-IgE was similar to that by antigen, but slower in start and shorter in duration compared with antigen. The results show that an increase in motility is essential for release mechanism of chemical mediators from basophils in antigen and anti-IgE stimulation, but not in Ca ionophore A23187 stimulation.

In vitro modulation of LPS/calcimycin induced inflammatory and allergic mediators by pure compounds of Andrographis paniculata (King of bitters) extract.

The aim of the current study is to probe the anti-inflammatory/anti-allergic potential of seven phytoconstituents (andrographolide, neoandrographolide, isoandrographolide, andrograpanin, 14-deoxy-11,12-didehydroandrographolide, 7-O-methylwogonin and skullcapflavone-I) isolated from Andrographis paniculata (King of bitters) on the production of key inflammatory/allergic mediators (NO, PGE(2), IL-1 beta, IL-6, LTB(4), TXB(2) and histamine). The results demonstrated that andrographolide, isoandrographolide, 7-O-methylwogonin and skullcapflavone-I significantly inhibited LPS stimulated NO and PGE(2) release in J774A.1 macrophages. Andrographolide, isoandrographolide and 7-O-methylwogonin showed considerable inhibition of IL-1 beta production in LPS elicited macrophages. LPS induced IL-6 production was significantly inhibited by andrographolide, isoandrographolide and skullcapflavone-I in a concentration dependent manner. The results revealed that andrographolide, isoandrographolide and skullcapflavone-I significantly decreased TXB(2) release in A23187 activated HL-60 promyelocytic cells. Furthermore, the anti-allergic properties of the phytoconstituents was investigated on A23187 induced LTB(4) production (HL-60 cells) and histamine release (RBL-2H3 basophilic cells). The results showed that only skullcapflavone-I and 7-O-methylwogonin showed marked inhibitory effect on LTB(4) production, however, only 7-O-methylwogonin exerted dose-dependent inhibition towards histamine release. Therefore, this study indicates that some of these phytoconstituents exhibit potent anti-inflammatory/anti-allergic effects by modulating different inflammatory/allergic mediators. Hence, these phytoconstituents might provide useful phytomedical treatment against variety of inflammatory and allergic disorders.

Inhibitory effects of thunberginols A and B isolated from Hydrangeae Dulcis Folium on mRNA expression of cytokines and on activation of activator protein-1 in RBL-2H3 cells.

Previously, thunberginols A and B from the processed leaves of Hydrangeae macrophylla var. thunbergii (Hydrangea dulcis folium) substantially inhibited the degranulation caused by antigen and calcium ionophore A23187, and the release of tumor necrosis factor (TNF)-alpha and interleukin (IL)-4 by antigen in RBL-2H3 cells. In the present study, we examined the effect of thunberginol B on the expression of mRNA of several cytokines [ILs-2, 3, 4 and 13, TNF-alpha and granulocyte/macrophage-colony stimulating factor (GM-CSF)] and effects of thunberginols A and B on activator protein (AP)-1 composed of c-jun and c-fos, which is essential for the expression of the cytokine mRNA, in RBL-2H3 cells. Thunberginol B inhibited up-regulated genes of all cytokines, and thunberginols A and B (30 microM) inhibited the phosphorylation of c-jun and expression of c-fos mRNA and phosphorylation of extracellular signal-regulated kinases (ERK1/2). In addition, the profile of gene expression by thunberginol B was similar to that by luteolin, a natural flavone with a potent anti-allergic effect.

Aberrant TNF secretion by whole blood in healthy subjects with a history of reactive arthritis: time course in adherent and non-adherent cultures.

BACKGROUND: The pathogenesis of reactive arthritis (ReA) apparently involves aberrations in innate immune functions such as monocyte tumour necrosis factor (TNF) generation. OBJECTIVE: To investigate TNF production in healthy subjects with previous yersinia triggered reactive arthritis. METHODS: The study comprised HLA-B27 positive subjects with previous reactive arthritis (B27+ReA+), and B27+ReA- and B27-ReA- subjects (n = 15 each). Whole blood TNF production was induced by lipopolysaccharide (LPS), which binds to CD14/TLR4 on the monocyte surface, or by a combination of phorbol 12-myristate 13-acetate (PMA) and Ca(2+) ionophore A23187, which activates monocytes independently of cell surface receptors. To further evaluate the possible role of adhesion mediated signalling on TNF production, blood samples were incubated in adherent or non-adherent conditions. TNF levels in culture supernatants were measured using an automated immunoassay analyser. The CD14(-159)C/T genotype was determined by a cycle minisequencing method. RESULTS: B27+ReA+ supernatants had higher TNF levels than B27+ReA- supernatants in PMA/A23187 wells in two hour (p = 0.004) and four hour cultures (p = 0.001). Rapid initial TNF release took place in adherent but not in non-adherent conditions. This adhesion associated difference was greater in the B27+ReA+ group than in the B27+ReA- or B27-ReA- group in response to PMA/A23187 (p values <0.001), and greater in the B27+ReA+ group than in the B27-ReA- group in response to LPS (p = 0.021). CD14(-159)T was associated allele dose dependently with an increase in the LPS induced TNF secretion allele (p = 0.030). SUBJECTS: who have recovered from yersinia arthritis show enhanced TNF production, which may be regulated at the level of monocyte adhesion.

Flow-cytometric analysis of human basophil degranulation. II. Degranulation induced by anti-IgE, anti-IgG4 and the calcium ionophore A23187.

Quantification of human basophil degranulation induced by anti-IgE, anti-IgG4, and by ionophore was performed using a flow-cytometric system. It was shown that these antibodies and ionophore can degranulate basophils in a dose-dependent manner, and that there is a wide variation in the response of basophils obtained from different individuals to these stimuli. A significant correlation was observed between the degree of degranulation induced by anti-IgE and anti-IgG4, while this was not the case for anti-IgE and ionophore. It was also shown that IgG4 myeloma protein can passively sensitive basophils. In general, degranulating efficacy was in the order of ionophore greater than anti-IgE greater than anti-IgG4, both in allergic and non-allergic individuals.

Immunologic release of heparin from purified rat peritoneal mast cells.

High m.w. [35S]heparin, labeled in vivo or in vitro, was released from purified rat mast cells by challenge with rabbit anti-rat F(ab')2, guinea pig anti-rat IgE, or calcium ionophore. The released and the residual heparin were isolated by Dowex 1 chromatography and were of comparable size by Sepharose 4B gel filtration. The majority of the released heparin was found by differential centrifugation to be granule-associated. Net percentage of mast cell heparin release, quantitated by metachromasia after isolation on Dowex 1 chromatography, correlated in a linear fashion with net percentage of histamine release, with heparin exhibiting a threshold requirement for onset of release. The correlation of histamine and high m.w. heparin release provides chemical support for the conclusion of others from ultrastructural studies that mast cell activation by immunologic means or by the calcium ionophore results in secretion of the whole granule.

Murine hypersensitivity pneumonitis: evidences for the role of eicosanoids and platelet activating factor.

Eicosanoids and platelet activating factor (PAF) are involved in numerous lung diseases. However, few studies have looked for their role in hypersensitivity pneumonitis (HP). HP was induced in mice by repeated instillations of Saccharapolyspora rectivirgula (Micropolyspora faeni) during 3 weeks. Bronchoalveolar lavages (BAL) were performed each week. BAL macrophage, lymphocyte and neutrophil counts increased at week 1, for a maximal increase after 3 weeks. Production of LTB4, LTC4, PGE2 and TXB2 by alveolar macrophages stimulated in vitro with calcium ionophore was maximal after 3 weeks, the appearance of PGE2 and TXB2 preceding that of LTB4 and LTC4. Eicosanoid production by AM correlated with BAL cell counts. To look for the importance of PAF in the development of experimental HP, mice were treated with BN52021 and BN50730, two PAF antagonists, and BAL were performed after 3 weeks of treatment. The compounds BN52021 and BN50730 reduced total BAL cell counts (x 10(5) cells/ml) in animals treated with S. rectivirgula from 8.4 +/- 0.8 to 4.4 +/- 1.1 and 3.7 +/- 0.2 respectively. BAL cell numbers in control animals were 0.4 +/- 0.1. In conclusion, eicosanoids are increased in experimental HP, and, as PAF, could play a role in the accumulation of alveolar cells.

Expression of lacto-N-fucopentaose III (CD15)- and sialyl-Lewis X-bearing molecules and their functional properties in eosinophils from patients with the idiopathic hypereosinophilic syndrome.

As the carbohydrate lacto-N-fucopentaose III (CD15 antigen or X-determinant) and its sialylated derivative sialyl-Lewis X are involved in the adhesion of cells rolling along the surface of endothelial cells, experiments were done to study the presence of these molecules on human eosinophils from patients with the idiopathic hypereosinophilic syndrome. Normal-density eosinophils from some patients showed higher levels of expression for lacto-N-fucopentaose III than light-density eosinophils. In contrast, sialyl-Lewis X was highly expressed by light-density eosinophils. Activation of normal-density eosinophils with calcium ionophore A23187 resulted in increased expression of these molecules for a short time. Monoclonal antibodies to these carbohydrates stimulated eosinophils to secrete eosinophil cationic protein, but not eosinophil peroxidase, and acted as costimulatory signals for C3b-induced degranulation of eosinophil cationic protein. It was suggested that CD15 and sialyl-Lewis X might contribute to eosinophil-mediated tissue injury in patients with the idiopathic hypereosinophilic syndrome.