Mastoid pneumatization in children with congenital cholesteatoma: an aspect of the formation of open-type and closed-type cholesteatoma

We investigated the effect of spirulina on mast cell-mediated immediate-type allergic reactions. Spirulina dose-dependently inhibited the systemic allergic reaction induced by compound 48/80 in rats. Spirulina inhibited compound 48/80-induced allergic reaction 100% with doses of 100-1000 microg/g body weight, i.p. Spirulina (10-1000 microg/g body weight, i.p.) also significantly inhibited local allergic reaction activated by anti-dinitrophenyl (DNP) IgE. When rats were pretreated with spirulina at a concentration ranging from 0.01 to 1000 microg/g body weight, i.p., the serum histamine levels were reduced in a dose-dependent manner. Spirulina (0.001 to 10 microg/mL) dose-dependently inhibited histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. The level of cyclic AMP in RPMC, when spirulina (10 microg/mL) was added, transiently and significantly increased about 70-fold at 10 sec compared with that of control cells. Moreover, spirulina (10 microg/mL) had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha production. These results indicate that spirulina inhibits mast cell-mediated immediate-type allergic reactions in vivo and in vitro.     

Effect of an active metabolite of the antiallergic agent tazanolast on histamine release from rat mast cells

WP-871 (3'-(1H-tetrazol-5-yl)oxanilic acid monohydrate, CAS 114607-46-4) is a monohydrate of a main active metabolite of tazanolast (butyl 3'-(1H-tetrazol-5-yl) oxanilate, CAS 82989-25-1), an orally active antiallergic drug. WP-871 inhibited dose-dependently compound 48/80-induced histamine release from rat peritoneal mast cells. In a similar dose range, WP-871 was effective in inhibiting compound 48/80-induced 45Ca uptake into mast cells from extracellular medium and compound 48/80-induced translocation of protein kinase C from the cytosol to the membrane fraction of mast cells. WP-871 also inhibited inositol trisphosphate production but did not exhibit a direct inhibitory effect on phospholipase C in mast cells. WP-871 caused no increase in cAMP content in mast cells. These results suggest that WP-871 may inhibit histamine release mainly by preventing the increase in intracellular Ca2+ concentration, which is a critical event in signal transduction leading to histamine release in mast cells.     

Dual regulation of the Na+/H(+)-exchange in rat peritoneal mast cells: role of protein kinase C and calcium on pHi regulation and histamine release

1. The purpose of this study was to compare the actions of phorbol 12-myristate 13-acetate (PMA) and ionomycin on Na+/H+ exchange activation and histamine release to that of compound 48/80 in order to study the possible relationship between pHi and secretion of histamine in rat peritoneal mast cells. 2. Resting pHi in mast cells suspended in a bicarbonate-free physiological salt solution amounted to 6.73 +/- 0.05 (mean +/- s.d., n = 52). 3. PMA (20 nM) induced a substantial but rather slow increase in pHi. This response was very sensitive to inhibition by staurosporine, very sensitive to inhibition by 5-(N,N-hexamethylene)amiloride (HMA), insensitive to the absence of extracellular calcium (without EGTA), and sensitive to partial depletion of intracellular calcium with EGTA. 4. Ionomycin (1 microM) induced a biphasic change in pHi that was sensitive to inhibition by HMA, insensitive to staurosporine. In the absence of extracellular calcium using EGTA, the biphasic response disappeared, leaving only a slow, and diminished change in pHi. 5. The effects of ionomycin and PMA on pHi were additive. 6. Addition of the secretagogue compound 48/80 (1 microgram ml-1) increased pHi, substantially, delta pHi amounting to 0.29 +/- 0.05 pH-units (n = 4). The biphasic pHi-response was insensitive to the absence of extracellular calcium (without EGTA). The initial fast response in pHi was, however, inhibited by HMA, not staurosporine. 7. The finding that staurosporine and HMA each inhibited approximately half of the compound 48/80-induced pHi-response, whereas both inhibitors completely abolished the compound 48/80-induced pHi-response seems to indicate that two independent pathways for the activation of the Na+/H+ exchange were stimulated by compound 48/80. 8. The histamine release induced via both PKC activation (using PMA) and calcium (using ionomycin) were much larger than the sum of each activation pathway, whereas in the absence of extracellular calcium using EGTA, the histamine release in response to PMA and ionomycin was completely abolished. 9. The compound 48/80-induced histamine release was partially sensitive to inhibition by HMA (approximately 30% inhibition) and partially sensitive to inhibition by staurosporine (approximately 50% inhibition). Preincubation with staurosporine and HMA before stimulation with compound 48/80 showed the same degree of inhibition as observed after staurosporine alone, even though this combination of drugs completely inhibited the pHi-response. Furthermore, compound 48/80-induced histamine release was not dependent on the presence of extracellular calcium (with and without EGTA). 10. In spite of the similarities in second messenger pathways for pHi regulation and histamine release, it is, however, not very likely that these two processes are directly related. It is, however, possible, that an increase in pHi plays a permissive, rather than an essential role for histamine release in rat peritoneal mast cells. This hypothesis was supported by the finding that preincubation with the Na+/H+ exchange-inhibitor HMA inhibited 30% of the compound 48/80-induced histamine secretion.     

Inhibition of immediate type allergic reactions by the aqueous extract of Kum-Hwang-San

We studied the effect of aqueous extract of Kum-Hwang-San (KHS) on mast cell-mediated immediate type allergic reactions. KHS (1-100 microg/site) inhibited concentration-dependently mast cell-dependent ear swelling response induced by compound 48/80 (200 microg/site) in mice by both topical and intradermal application. KHS (0.1-100 microg/site) inhibited concentration-dependently passive cutaneous anaphylaxis induced by anti-dinitrophenyl (DNP) IgE in rats by both topical and intradermal application. KHS also inhibited concentration-dependently the histamine release from the rat peritoneal mast cells (RPMC) by compound 48/80 and anti-DNP IgE. Moreover, KHS had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha (TNF-alpha) secretion from RPMC. These results indicate that KHS inhibits immediate type allergic reactions by inhibition of histamine release and TNF-alpha secretion from mast cells in vivo and in vitro.     

Studies on cytosolic 5SrRNA-L5 protein particles (5SRNP) of rat liver

Effects of antiallergic drugs on bradykinin-induced histamine release and intracellular Ca2+ release from peritoneal mast cells were studied in rats. Bradykinin caused a concentration-dependent histamine release as well as Ca2+ release from the intracellular Ca store of peritoneal mast cells. Antiallergic drugs used in this study showed an inhibition of not only histamine release but also Ca2+ release. The Ca2+ release from the intracellular Ca store induced by bradykinin was more sensitive to antiallergic drugs than histamine release from mast cells. Mequitazine and terfenadine caused potent inhibitory effects on both responses, whereas effects of ketotifen and cromolyn sodium were relatively weak. In conclusion, histamine release from mast cells and intracellular C2+ release induced by bradykinin were inhibited by antiallergic drugs similar to those induced by substance P and compound 48/80.     

A novel embryogenetic mechanism for Currarino''s triad: inadequate dorsoventral separation of the caudal eminence from hindgut endoderm

We studied the effect of sulfasalazine on anaphylaxis. Sulfasalazine dose-dependently inhibited systemic anaphylaxis induced by compound 48/80 in rats. Sulfasalazine also inhibited local anaphylaxis activated by anti-dinitrophenyl (anti-DNP) IgE. Moreover, sulfasalazine dose-dependently inhibited histamine release in the peritoneal mast cells activated by compound 48/80 or anti-DNP IgE. All of these effects were comparable to those of the disodium cromoglycate (reference drug) tested. When sulfasalazine was added, the level of cAMP in rat peritoneal mast cells transiently and significantly increased about 6-fold compared with that of basal cells. Our studies provide evidence that sulfasalazine may be beneficial in the treatment of anaphylaxis.     

Effect of reference database on frequency estimates of polymerase chain reaction (PCR)-based DNA profiles

1. To assess the contribution of an aqueous extract of Ulmi radicis cortex (AEURC) in systemic anaphylaxis, compound 48/80 was used as a fatal anaphylaxis inducer in rats. 2. AEURC completely inhibited anaphylactic shock with a dose of 1.0 g/kg body weight (BW) 1 hr before injection of compound 48/80. 3. AEURC significantly inhibited serum histamine levels induced by compound 48/80. 4. AEURC (1.0 g/kg BW) also inhibited by 79.1% passive cutaneous anaphylaxis activated by anti-dinitrophenyl (DNP) IgE. 5. AEURC dose dependently inhibited the histamine release from the rat peritoneal mast cells (RPMCs) by compound 48/80. Moreover, AEURC had a significant inhibitory effect on anti-DNP IgE-induced histamine release and tumor necrosis factor-alpha production from RPMC. 6. The level of cAMP in RPMC, when AEURC was added, significantly increased compared with that of a normal control. 7. These results indicate that AEURC may possess strong antianaphylactic action.     

Effect of Rehmannia glutinosa on immediate type allergic reaction

We investigated the effect of aqueous extract of Rehmannia glutinosa steamed root (RGAE) on the allergic reactions in vivo and in vitro. RGAE dose-dependently inhibited systemic allergic reaction induced by compound 48/80. When RGAE was pre-treated at the same concentrations with systemic allergic reaction test, the plasma histamine levels were reduced in a dose-dependent manner. RGAE dose-dependently inhibited skin allergic reaction activated by anti-dinitrophenyl (DNP) IgE. RGAE also dose-dependently inhibited the histamine release from the rat peritoneal mast cells (RPMC) by compound 48/80 or anti-DNP IgE. Moreover, RGAE had significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha production of RPMC. These results indicate that RGAE may be beneficial in the regulation of immediate type allergic reaction.     

Inhibitory effects of apple polyphenol on induced histamine release from RBL-2H3 cells and rat mast cells

The anti-allergic activities of polyphenol fractions extracted from immature fruits of apple (Rosaceae, Malus sp.) were evaluated by in vitro assays. A crude apple polyphenol (CAP) fraction, which had been obtained from the juice of immature apples by reverse-phase column chromatography, was further purified by LH-20 column chromatography to obtain an apple condensed tannin (ACT) fraction consisting of linear oligomeric epicatechins from the dimer to pentadecamer. ACT strongly inhibited the release of histamine from rat basophilic leukemia (RBL-2H3) cells stimulated by the antigen-stimulation and from rat peritoneal mast cells stimulated by compound 48/80. The IC50 values for histamine release were 30 micrograms/ml and 25 micrograms/ml, respectively. ACT also inhibited hyaluronidase activity and the increase in intracellular free calcium concentration in RBL-2H3 cells stimulated with the antigen. These results suggest that ACT affected early signal transduction including the calcium influx.     

Dietary intake and functional ability between 70 and 76 years of age

In order to explore the potential existence of human mast cell growth factors other than stem cell factor (SCF), we have compared SCF to L-cell fibroblast supernatants (LCS) during in vitro mast cell differentiation, using human leukaemic mast cells (HMC-1 cells) which contain a gain-of-function mutated SCF receptor (c-Kit) as model. At baseline, cells exhibited an immature phenotype, with <25% being metachromatic or chloroacetate esterase, tryptase and FcepsilonRIalpha positive. Intracellular levels of histamine, tryptase, TNF-alpha and chymase were low, whereas 83% of cells were c-Kit positive. During a 10 day culture with 30% LCS, a significant, time-dependent increase of all mast cell markers, except for chymase and c-Kit, was observed at the protein and for tryptase and FcepsilonRIalpha also at the mRNA level. Cytoplasmatic granulation and stimulated histamine and leukotriene C4 release were increased as well. In contrast to LCS, rhSCF induced none of these changes in HMC-1 cells. On Sephadex G100 fractionation of LCS, HMC-1 cells increased tryptase activity with fractions between 40 and 60, and below 10 kDa, away from the SCF peak. These data show that HMC-1 cells fail to differentiate in response to SCF and that in addition to SCF, LCS contains other human mast cell growth factors.     

The mite allergen and allergoid stimulation of histamine secretion by mast cells

Rat peritoneal mast cells were incubated with serum from highly mite-sensitive patients. It was demonstrated that exposure of passive sensitized mast cells to allergen from mites Dermatophagoides farinae induced the release of histamine. Exposure of mast cells to 10 micrograms/ml and 50 micrograms/ml mite allergen resulted in an increase of histamine secretion to 48% of the basal level. The allergoid (formaldehyde-modified mite allergen) had poor histamine-releasing activity compared to allergen. The allergoid (50 micrograms/ml) induced a 2.5-fold decrease in histamine release. The allergen at the same concentrations and the same release as allergen in dose 0.1 microgram/ml.     

Mast cells enhance eosinophil survival in vitro: role of TNF-alpha and granulocyte-macrophage colony-stimulating factor

Mast cell-eosinophil interactions in allergy have not yet been completely defined. To determine whether mast cells influence eosinophil survival, human peripheral blood eosinophils were incubated with rat peritoneal mast cell sonicate. After 3 days, viable eosinophils in medium were 21.3% compared with 44% with mast cell sonicate. Like sonicate, supernatants of compound 48/80-activated mast cells enhanced eosinophil survival, demonstrating that the factor(s) involved is stored preformed and rapidly released. Increased eosinophil survival was due to an inhibition of apoptosis (morphologic analysis; annexin V/PI). Neutralizing Abs to granulocyte-macrophage CSF (GM-CSF), but not to IL-3 or IL-5, decreased by 61.7% the enhancing effect on eosinophil viability. Eosinophils are the source of GM-CSF since its release in the culture medium was inhibited by their incubation with the mast cell sonicate together with dexamethasone. In addition, eosinophils incubated with the sonicate expressed mRNA for GM-CSF. To partially characterize the mast cell-derived factor(s) increasing eosinophil survival, the sonicate was heated (56 degrees C/30 min or 100 degrees C/10 min) or preincubated with antihistamines or with anti-TNF-alpha-neutralizing Abs. Most of the activity was heat labile. TNF-alpha was found to be predominantly (70%) responsible, while histamine had no role. Mast cell sonicate also caused eosinophils to release eosinophil peroxidase and to display morphologic signs of activation. In conclusion, we have demonstrated that mast cells enhance eosinophil survival in part through their activation to produce and release the autocrine survival cytokine GM-CSF.     

Degranulation of individual mast cells in response to Ca2+ and guanine nucleotides: an all-or-none event

Widespread experience indicates that application of suboptimal concentrations of stimulating ligands (secretagogues) to secretory cells elicits submaximal extents of secretion. Similarly, for permeabilized secretory cells, the extent of secretion is related to the concentration of applied intracellular effectors. We investigated the relationship between the extent of secretion from mast cells (assessed as the release of hexosaminidase) and the degranulation (exocytosis) responses of individual cells. For permeabilized mast cells stimulated by the effector combination Ca2+ plus GTP-gamma-S and for intact cells stimulated by the Ca2+ ionophore ionomycin, we found that exocytosis has the characteristics of an all-or-none process at the level of the individual cells. With a suboptimal stimulus, the population comprised only totally degranulated cells and fully replete cells. In contrast, a suboptimal concentration of compound 48/80 applied to intact cells induced a partial degree of degranulation. This was determined by observing the morphological changes accompanying degranulation by light and electron microscopy and also as a reduction in the intensity of light scattered at 90 degrees, indicative of a change in the cell-refractive index. These results may be explained by the existence of a threshold sensitivity to the combined effectors that is set at the level of individual cells and not at the granule level. We used flow cytometry to establish the relationship between the extent of degranulation in individual rat peritoneal mast cells and the extent of secretion in the population (measured as the percentage release of total hexosaminidase). For comparison, secretion was also elicited by applying the Ca2+ ionophore ionomycin or compound 48/80 to intact cells. For permeabilized cells and also for intact cells stimulated with the ionophore, levels of stimulation that generate partial secretion gave rise to bimodal frequency distributions of 90 degrees light scatter. In contrast, a partial stimulus to secretion by compound 48/80 resulted in a single population of partially degranulated cells, the degree of degranulation varying across the cell population. The difference between the all-or-none responses of the permeabilized or ionophore-treated cells and the graded responses of cells activated by compound 48/80 is likely to stem from differences in the effective calcium stimulus. Whereas cell stimulated with receptor-directed agonists can undergo transient and localized Ca2+ changes, a homogeneous and persistent stimulus is sensed at every potential exocytotic site in the permeabilized cells.     

Effects of relaxin on mast cells. In vitro and in vivo studies in rats and guinea pigs

The results of the current study demonstrate that relaxin inhibits histamine release by mast cells. This effect is related to the peptide concentrations, and could be observed in both isolated rat serosal mast cells stimulated with compound 48/80 or calcium ionophore A 23187, and in serosal mast cells isolated from sensitized guinea pigs and challenged with the antigen. The morphological findings agree with the functional data, revealing that relaxin attenuates calcium ionophore-induced granule exocytosis by isolated rat serosal mast cells. Similar effects of relaxin have also been recognized in vivo by light microscopic and densitometric analysis of the mesenteric mast cells of rats which received the hormone intraperitoneally 20 min before local treatment of the mesentery with calcium ionophore. Moreover, evidence is provided that relaxin stimulates endogenous production of nitric oxide and attenuates the rise of intracellular Ca2+ concentration induced by calcium ionophore. The experiments with drugs capable of influencing nitric oxide production also provide indirect evidence that the inhibiting effect of relaxin on mast cell histamine release is related to an increased generation of nitric oxide. It is suggested that relaxin may have a physiological role in modulating mast cell function through the L-arginine-nitric oxide pathway.     

Human mast cell chymase induces the accumulation of neutrophils, eosinophils and other inflammatory cells in vivo

The roles of chymase in acute allergic responses are not clear, despite the relative abundance of this serine proteinase in the secretory granules of human mast cells. We have isolated chymase to high purity from human skin tissue by heparin-agarose affinity chromatography and Sephacryl S-200 gel filtration procedures, and have investigated the ability of human mast cell chymase to stimulate cell accumulation following injection into laboratory animals. Injection of chymase provoked marked neutrophilia and eosinophilia in the skin of Dunkin Hartley guinea-pigs. Compared with saline injected control animals, there were some 60 fold more neutrophils and 12 fold more eosinophils present at the injection site. Following injection of chymase into the peritoneum of BALB/c mice, there were up to 700 fold more neutrophils. 21 fold more eosinophils, 19 fold more lymphocytes and 7 fold more macrophages recovered than from saline injected controls at 16 h. Doses of chymase as low as 5 ng (1.7 x 10(-13) mole) stimulated an inflammatory infiltrate, and significant neutrophilia was elicited within 3 h. The chymase induced cell accumulation in both the guinea-pig and mouse models was dependent on an intact catalytic site, being reduced by co-injection of proteinase inhibitors or heat inactivation of the enzyme. Co-injection of histamine or heparin significantly reduced the chymase induced neutrophil accumulation, whereas neither histamine nor heparin by themselves had any effect on the accumulation of nucleated cells. No synergistic or antagonist interactions between chymase and tryptase were observed when these two major mast cell proteinases were co-injected into the mouse peritoneum. Our findings suggest that chymase may provide an potent stimulus for inflammatory cell recruitment following mast cell activation.     

Expression of protein kinase C gene family members is temporally and spatially regulated during neural development in vitro

The dog mastocytoma BR cell line provides us with a permanent source of canine mast cells, allowing a characterization of secretory mediators that exert important effects in canine allergic and nonallergic diseases and in physiological processes. We studied the ultrastructural characteristics and histamine releasing activity after immunological and non-immunological stimuli of the dog mastocytoma BR cell line, and compared the cell line to normal skin mast cells enzymatically isolated from healthy dogs. The histamine content of BR cells was 0.04 +/- 0.002 pg/cell, approximately 100-fold less than that found in canine skin mast cells. Non-immunologic stimuli induced similar concentration-dependent histamine release from skin mast cells and BR cells: 29.3 +/- 0.9% vs. 12.7 +/- 0.7% (calcium ionophore A23187), 23.3 +/- 0.7% vs. 18.8 +/- 0.7% (substance P) and 12.5 +/- 0.3% vs. 12.1 +/- 0.9% (compound 48/80), respectively. Immunologic stimulation, however, was only effective on canine skin mast cells, causing 30.9 +/- 1.7%, 27.7 +/- 0.6% and 12.2 +/- 0.9% histamine release in response to anti-canine IgE, concanavalin A, and antigen Asc S 1, respectively. The absence of functional IgE receptors in BR cells was confirmed by the lack of response to anti-IgE and antigen Asc S 1 following passive sensitization with dog atopic serum and dog antigen sensitized serum. We conclude that BR cells are able to release histamine after non-immunologic stimulation in a similar manner to canine skin mast cells, but that there are morphological and functional differences possibly due to different states of maturity or differentiation. For this reason the study of the highly homogeneous BR cells could offer insights into dog mast cell biology in contexts where freshly isolated cells cannot be used because of low purity and recovery.     

Stimulation of inositol phosphate production and GTPase activity by compound 48/80 in rat peritoneal mast cells

Phospholipase C activity, GTPase activity and cytosolic-free calcium concentration in mast cells were stimulated by compound 48/80. Accumulation of inositol phosphates in rat mast cells was stimulated by guanosine 5'-[gamma-thio]-triphosphate. Guanosine 5'-[gamma-thio]triphosphate, however, exhibited no effect upon the purified phospholipase C activity and upon phospholipase C in the mast cell homogenate. The stimulatory effect of compound 48/80 upon phospholipase C activity of intact mast cells was observed to have been well correlated with that on GTPase activity of mast cell homogenate. Compound 48/80 exhibited no effect upon the binding of radioactive guanosine 5'-[gamma-thio]triphosphate to mast cell homogenate. Phospholipase C activity was verified by the above results to become affected by compound 48/80 through guanine nucleotide-binding regulatory protein.     

The role of mast cell-derived histamine in the closure of an in vitro wound

We have previously reported that mast cells (MC) stimulate 3T3 fibroblast migration and proliferation into an in vitro model of wound obtained by producing in a confluent 3T3 monolayer, a midline cut and by scraping the cells from half of the monolayer. The purpose of the present study was to determine the contribution of mast cell-derived histamine to this MC increasing effect. Histamine levels in supernatants of MC/ 3T3 cultures unactivated or activated with either compound 48/80 or anti-IgE antibodies (10 min) did not correlate to the degree of fibroblast migration and proliferation into the wound space (42 h). Various concentrations of histamine were added to 3T3 fibroblast monolayers in the absence of cocultured MC, and fibroblasts beyond the wound line were counted (42 h). Addition of 100 ng/ml histamine had the highest stimulating effect on fibroblast numbers. This effect was abrogated by the addition of cimetidine (an H-2 antagonist). Addition of cimetidine to unactivated MC/ 3T3 cultures did not affect the increasing activity of MC presence on the wounded monolayer, although it diminished the enhancing effect obtained after MC activation with compound 48/80. These results indicate that histamine is partially responsible for the mast cell enhancing effect on fibroblast migration and proliferation in an in vitro model of wound.     

The effect of okadaic acid on histamine release, cell morphology and phosphorylation in rat basophilic leukemia (RBL-2H3) cells, human basophils and rat peritoneal mast cells

To study the involvement of serine/threonine phosphatase in the signal transduction of mast cells, we examined the effects of okadaic acid (OA), an inhibitor of type-1 and -2A phosphatase on histamine release, cell morphology, calcium influx and protein phosphorylation of rat basophilic leukemia (RBL-2H3) cells, human basophils and rat peritoneal mast cells. OA inhibited IgE-mediated histamine release from RBL-2H3 cells and human basophils dose-dependently. There was a remarkable enhancement of IgE-mediated histamine release when rat peritoneal mast cells were suboptimally challenged. OA induced a marked change of cell features, detached RBL-2H3 cells from plastic well and kept the 18- and 68-kD proteins phosphorylated. These findings show that phosphatase may play a role in the modulation of secretion in mast cells.     

The histamine releasers crotamine, protamine and compound 48/80 activate specific proteases and phospholipases A2

Crotamine, a basic, myonecrotic, histamine-releasing neurotoxin, was isolated from Crotalus durissus terrificus venom. Carboxypeptidase A was shown to be activated by crotamine when acting upon N-carbobenzoxyglycil-L-phenylalanine. However the activity of carboxypeptidase B upon the substrate hippuryl-L-arginine was not enhanced by this toxin. Teh basic histamine releasers protamine and compound 48/80 also activated carboxypeptidase A. These three agents activated both alpha-chymotrypsin when acting upon acetyl-L-tyrosine ethyl ester and also five snake venom phospholipase-like myotoxins acting upon egg yolk phosphatidylcholine. These findings suggest that the action of these agents during histamine release may involve the participation of specific intermediary hydrolases which, upon activation, would enhance their cytolytic effects on the sequence of events which lead to granule extrusion and histamine release from mast cells.