Enhancement of leukotriene C4 release from primate airway macrophages by cellular interactions.

1. Cells were obtained from the lungs of Macaque monkeys by bronchoalveolar lavage in order to study the role of cellular interactions in the release of leukotriene C4 (LTC4). 2. In normal monkeys, macrophages were the most abundant cell type recovered, whereas in monkeys sensitized with Ascaris suum there was an increase in the numbers of eosinophils and mast cells recovered. 3. Challenge of cells from both groups of animals with an optimal concentration of opsonized zymosan (OPZ) resulted in the time-dependent release of LTC4 from macrophages. However, release was significantly greater in cells obtained from sensitized donors compared to normal donors. 4. Density-gradient centrifugation of cells lavaged from sensitized donors was used to prepare fractions containing both eosinophils and mast cells. Addition of these cells to macrophage populations obtained from non-sensitized donors caused a significant enhancement of OPZ-induced LTC4 release. In the absence of macrophages no significant release of LTC4 was detected from eosinophil/mast cell-containing fractions stimulated with OPZ, despite the fact that the zymosan had been phagocytosed by the eosinophils. 5. There was a significant correlation between the percentage enhancement of LTC4 release and the number of eosinophils added. However, there was not a significant correlation with the number of mast cells added. 6. These results suggest that a cellular interaction between macrophages and eosinophils may be important in the regulation of mediator synthesis and release. The precise mechanism of this effect remains to be elucidated.

Characterization of primate bronchoalveolar mast cells. II. Inhibition of histamine, LTC4, and PGD2 release from primate bronchoalveolar mast cells and a comparison with rat peritoneal mast cells.

As described in the preceding companion paper, bronchoalveolar lavage (BAL) of the primate Macaca arctoides infected with the nematode Ascaris suum yields a population of cells containing a high proportion of mast cells (21%). Nedocromil sodium, a new drug undergoing clinical evaluation for the treatment of reversible obstructive airways disease, inhibited the release of histamine, LTC4, and PGD2 from these cells challenged with antigen (with IC30 values of 2.1 X 10(-6) M, 2.3 X 10(-6) M, and 1.9 X 10(-6) M, respectively) and with anti-human IgE (IC30 values of 4.7 X 10(-6) M, 1.3 X 10(-6) M, and 1.3 X 10(-6) M, respectively). Cromolyn sodium was essentially inactive. Histamine release from rat peritoneal mast cells induced by anti-rat IgE was, however, inhibited by both nedocromil sodium and cromolyn sodium with IC30 values of 1.1 X 10(-6) M and 5.5 X 10(-7) M, respectively. Both compounds induce phosphorylation of a 78,000 m.w. protein in the rat peritoneal mast cell in the absence of any stimulus at the same concentrations as those required to inhibit histamine release stimulated by anti-IgE. This event may be part of a feedback mechanism to limit degranulation. Nedocromil sodium and cromolyn sodium were equipotent in their ability to inhibit anti-IgE-induced histamine release from rat peritoneal mast cells, but differed markedly in their ability to inhibit histamine release from macaque BAL cells.

Characterization of primate bronchoalveolar mast cells. I. IgE-dependent release of histamine, leukotrienes, and prostaglandins.

Large numbers of functional mast cells were obtained by bronchoalveolar lavage (BAL) of Macaca arctoides monkeys that had been infected with the nematode Ascaris suum. These lavage cells, of which 21% were mast cells, released histamine, LTC4, and PGD2 in a concentration-dependent fashion when challenged with ascaris antigen or antibody to human IgE. However, there was no release of histamine when these cells were challenged with compound 48/80. The amount of mediator released was highly dependent on the sensitivity of the cells to immunologic challenge, but was generally in the range of 2 to 5 micrograms histamine (30 to 70% of total), 20 to 80 ng LTC4, and 100 to 300 ng PGD2 per 10(6) mast cells when maximally challenged. Other eicosanoids measured were released only in much smaller quantities. Maximal values were 4 ng LTB4, 2 ng PGE2, and approximately 10 to 20 ng PGF2 alpha per 10(6) mast cells. The amount of LTC4 and PGD2 released correlated with the release of histamine, the calculated regression line indicating that 18 ng LTC4 and 50 ng PGD2 were released per microgram of histamine released. This correlation suggests that the majority of the LTC4 and PGD2 released was probably mast cell-derived. Further support for this conclusion was given by the observation that when lavage cells were fractioned on continuous Percoll gradients, the ability to release LTC4 and PGD2 on immunologic challenge coincided with the peak of mast cells.

The anti-allergic effects of FPL 52694.

The substituted chromone carboxylic acid FPL 52694 inhibited models of IgE-mediated immediate hypersensitivity reactions in the rat by a mechanism similar to that of sodium cromoglycate. The compound was more potent than sodium cromoglycate but unlike cromoglycate was active following oral administration.

Laboratory infection of primates with Ascaris suum to provide a model of allergic bronchoconstriction.

Wild-caught non-human primates are naturally sensitive to Ascaris antigen and provide a useful model for studying atopic asthma. The present study was carried out to determine the effect of experimentally infecting home-bred macaques with the nematode Ascaris suum and hence provide an alternative for the naturally occurring model. Following oral infection with the parasite the animals developed a blood eosinophilia and specific antibodies to purified Ascaris antigen. These antibodies appeared to be of the IgE class as they could be detected by a radiometric assay using a radiolabelled antibody to human IgE. However, on further investigation, using the passive cutaneous anaphylaxis test, two classes of antibody were found, a heat labile (56 degrees C) and a heat stable antibody. Lung lavage cells taken from monkeys infected with Ascaris suum were shown to include cells morphologically characteristic of mast cells and released histamine when challenged in vitro with Ascaris antigen. Hence this model of immediate hypersensitivity provides a simple alternative to the less accessible natural model.

Effects of locus coeruleus lesions upon cerebral monoamine content, sleep-wakefulness states and the response to amphetamine in the cat.

The purpose of the present study was to investigate the effects of complete lesions of the noradrenaline locus coeruleus neurons upon wakefulness and paradoxical sleep. Radiofrequency lesions of the nucleus were performed in 8 chronically implanted cats which were continuously recorded with an EEG for 5 days prior to and 21 days following the lesions, when they were sacrificed. In 3 of these animals amphetamine (2 mg/kg) was administered on one control day and on the 10th day post-lesion. Following sacrifice, monoamine content was assayed in discrete brain regions, and the lesion was examined in Nissl-stained sections of the pons. (1) The majority (x 69%) of the locus coeruleus was bilaterally destroyed by the lesions which only minimally exceeded the boundaries of the nucleus within the dorsolateral pontine tegmentum. Noradrenaline was depleted by a mean of 85% in the paleo- and neocortex and by a mean of 60% in the thalamus and midbrain. (2) EEG activation reappeared within 12-48 h following the lesion and represented a normal percentage of recording time on the 3rd and subsequent days post-lesion. The behavioral arousal and long-lasting EEG activation produced by amphetamine was qualitatively and quantitatively the same pre- and post-lesion. (3) Despite alteration of certain components, paradoxical sleep reappeared within 48 h and recovered to normal amounts by the second week post-lesion. Muscle atonia was permanently absent in 7 animals. Ponto-geniculo-occipital (PGO) spiking was acutely redistributed across all states and chronically reduced in frequency (by a mean of 50%) within paradoxical sleep. These results indicate that the noradrenaline locus coeruleus neurons are not necessary for the tonic maintenance of EEG activation that occurs in normal wakefulness and in amphetamine-produced arousal. Furthermore, these neurons are not necessary for the occurrence of paradoxical sleep, although they may be involved in modulation of PGO spiking.