S. A. Patkar

Histamine Release from Washed Whole Blood

Measurement of histamine release from basophilic leukocytes is a useful tool in the diagnosis of type I allergy. The modifications described in this paper – among others, the use of washed whole blood

Sodium fluoride--a stimulus for a calcium-triggered secretory process.

Calcium triggers the secretion of histamine from mast cells after previous exposure of the cells to sodium fluoride. The secretory process can be divided into a fluoride-activating step and a calcium-induced secretory step dependent on cellular metabolic energy. The secretory response induced by compound 48/80 in the absence of extracellular calcium was found to decrease after fluoride pretreatment of the cells. The response was, however, unaffected, provided calcium was introduced to the cells simultaneously with compound 48/80.

Does Cyclic AMP Play Any Role in Histamine Release from Rat Mast Cells

In recent years there has been an explosive development in research concerning the regulatory role of cyclic AMP. Each year a number of publications bring direct and indirect information about the alleged functions in various biological systems. Histamine release from mast cells and basophils is one of the functions considered to be controlled by cyclic AMP. An elevation of cyclic AMP in target cells is generally regarded to inhibit histatnine secretion and the process would hereby conform to a bidirectional regtilatory system (Berridge: Adv. Cyclic Nuc!. Res. 6. 1, 1975). However, this opinion can now be questioned, since data have appeared in the literature which oppose this general concept. The steady accumulation of contradictory information in this area has stimulated us to survey reports dealing with the cyclic AMP content of secretory cells and its regulatory function on histamine release. Considering possible tissue and species differences, we have chosen to analyse only the reports dealing with isolated rat mast cells, since these cells can be obtained as a pure cell population, which is a prerequisite for proper evaluation of the significance of cyclic AMP data. Furthermore, we have focused interest only on investigations where direct measurements of cyclic AMP have been performed. Table 1 shows the basal levels of cyclic AMP in rat mast cells in various investigadons. The values vary by a factor of about 50. This large variation is difficult to explain even when taking into account differences in experimental procedures: incubation media, strains of rats, and methods

Histamine Release by Calcium from Sodium Fluoride-Activated Rat Mast Cells. Further Evidence for a Secretory Process

Histamine release induced by calcium (step 2) from fluoride-activated (step 1) rat mast cells was found to be dependent on temperature and pH. Whereas the influence of temperature was different on the two steps, the pH effects were similar. The activation of the cells by fluoride occurred faster at low pH. Agents considered to influence cyclic nucleotide content of the cells neither influenced fluoride activation nor the secretory action of calcium, except for theophylline which inhibited the second step and shared this effect with lidocaine and several other agents known to act as inhibitors of histamine secretion. The time course for the action of fluoride to inhibit subsequent histamine release by compound 48/80 in the absence of extracellular calcium was somewhat faster than its action to activate the cells to the secretory action of calcium. In the absence of calcium, no cyclic AMP could be detected in the cells. In the presence of 1 mM calcium, 2.5 pmol/106 cells cyclic AMP was found which decreased by the presence of fluoride. No uptake of 45Ca was observed in fluoride-activated mast cells in the absence of release. Furthermore, fluoride did not activate isolated mast cell granules to release histamine when challenged with calcium. The results suggest that calcium-induced histamme secretion from fluoride-activated cells conforms to a secretory system which, in many respects, is governed by similar regulatory factors as for antigen and other secretagogues.

Studies on the action of the calcium ionophore A 23187 on isolated rat mast cells.

A water-soluble agent which releases histamine from human and pig lung in vitro is present in dust from the cardrooms of cotton mills [1, 2]. There is also evidence that the acute changes in respiratory function observed in volunteers after inhalation of cotton dust are associated with a release of histamine [3]. In the present study the nature of the histamine releasing mechanism has been examined using an in vitro technique in which aqueous extracts of cotton dust were incubated with chopped pig lung [2]. The amount of water-soluble extractives is expressed in terms of the weight of cotton dust from which it had been derived. At pH 7.4 a dose-response relationship for histamine release was exhibited over the concentration range 10-150 mg cotton dust/ml of incubation medium, and up to 15% of the total lung histamine was released at the maximally effective level. The histamine releasing activity of cotton dust (27 mg/ml) was both temperatureand pH-dependent, the optima being 37 ~ and pH 7.4 respectively. However, at a concentration of 83 mg/ml, histamine release was increased when the pH was raised from 7.4 to 8.2. A Ca/Mg-free medium inhibited the release of histamine by 27 mg/ml of Cotton dust. In the absence of glucose, potassium cyanide (10 -3 M) reduced the histamine released by 27 mg/ml of cotton dust by 25%, but potentiated the activity of 83 mg/ml of the dust. The inclusion in the medium o f either 2,4-dinitrophenol (5 x 10-4 M glucose-free medium), ninhydrin (10 .3 M ) o r N-ethylmaleimide reduced the histamine releasing activity of 27 mg/ml of cotton dust by 95%, 55% and 30% respectively. These results are interpreted as indicating that in pig lung the cotton dust-mediated histamine release appears to be largely an energy-dependent mechanism. However, at a dust concentration of 83 mg/ml an energyindependent mechanism may also operate.

Mechanism of Histamine Release Induced by the Ionophore X537A from Isolated Rat Mast Cells

X537A released histamine from isolated histamine-retaining mast cell granules incubated at 37 degrees C in Tris-sodium (150 mM) or Tris-potassium (150 mM), but not in Tris-glucose (300 mM). The release was depressed at 0 degrees C. In contrast, decylamine released all histamine bound to the granules irrespective of the presence of monovalent cations in the incubation medium of temperature. X537A did not release histamine from an artificial heparin-protamine complex when incubated in deionized water. The mechanism of histamine release by X537A can be explained by the ability of the ionophore to carry monovalent cations across cellular membranes, hereby making the ions available for exchange with histamine bound to the granular matrix. This mechanism can be distinguished from that of agents triggering an exchange between cations and bound histamine through a calcium- and energy-dependent exocytotic process on the one hand and through membrane lysis on the other. Based on the observation that the ionophore was able to carry histamine into the bulk of an organic phase, various possibilities exist to explain how histamine escapes from the cells following release from intracellular granular stores.

The mechanism of histamine release induced by the ionophore X537A from isolated rat mast cells. II. The relationship between increase of cell volume and histamine release.

The ionophore X537A induced swelling of isolated rat mast cells parallel to histamine release. Both actions were depressed by extracellular calcium and BSA, temperatures below 37°C, NEM, PMSF, and TTX, and were enhanced by high potassium and pretreatment of the cells with ATP. DSCG, theophylline, and DFP enhanced the histamine release noted after 10 min of incubation without influencing the swelling action of X537A. The swelling action could not be separated from histamine release and it is suggested that it right be inherent in the mechanism of secretion induced by X537A. The present results further distinguish histamine release induced by the two ionophores X537A and A23187.

Calcium-dependent histamine release from isolated rat mast cells induced by sodium fluoride—A two-step reaction

ConclusionThe release process induced by fluoride and calcium can be divided into two separate steps. A slow activating step induced most likely by binding of fluoride to the cells and an energy-dependent secretory step induced by calcium. This opens possibilities for further studies as to the nature of individual steps of the secretory process of histamine from isolated rat mast cells.

On the inhibitory action of DFP and PMSF on histamine release from isolated rat mast cells

ConclusionThe present results furnish an alternative explanation to the inhibition of histamine release induced by so-called esterase inhibitors. The inhibition can well be explained on the basis that these agents inhibit metabolic energy production necessary for the coupling of stimulation to secretion in the rat mast cells.

Monovalent cation-dependent histamine release from rat peritoneal mast cells by ionophore X537A

ConclusionsThe results indicate that X537A exerts its histamine-releasing action only in the presence of monovalent cations. The release is not dependent on either extra- or intracellular calcium, in fact extracellular calcium depressed the release. The finding that the release occurred faster in a potassium medium indicates that high potassium increased the permeability of the plasma membrane for X537A or that X537A carries potassium more efficiently over the cell membrane as compared to sodium, in spite of the finding that the affinity of X537A is of the same order for both cations [5]. According to the latter possiblity, monovalent cations would accumulate in the cell and be available for exchange with histamine bound to the granular matrix. Furthermore, the observation that lack of cellular metabolic energy slows down the release process might indicate that metabolic energy influences the penetration of X537A at limiting concentrations. The slow release of histamine induced by X537A in comparison to many calcium- and energy-dependent releasing agents further indicates a different type of mechanism for release.