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PubMed2000

Evidence of eosinophil, neutrophil, and mast-cell mediators in the effusion of OME patients with and without atopy.

BACKGROUND: This study was designed to measure the involvement of eosinophils, neutrophils, and mast cells in the middle ear of patients with OME and to see whether that inflammatory response differed depending on whether or not the patient was atopic. METHODS: Levels of ECP, MPO, and tryptase were measured in effusion from 97 patients whose atopic status was determined by in vitro testing with 12 inhalants and five foods. RESULTS: Seventy-nine of 97 OME patients (81%) were atopic, among whom 86% (68/79) had elevated levels of effusion ECP, and 64% (23/36) had elevated tryptase. Mean ECP was 166 microg/l vs 3.38 microg/l, mean MPO was 6231 microg/l vs 116 microg/l, and mean tryptase was 4.8 microg/l vs 1.34 microg/l in atopic vs nonatopic ears. Total serum IgE did not differ between atopics and nonatopics (P=0.28). CONCLUSIONS: The inflammatory response by eosinophils, neutrophils, and mast cells in the middle ear was distinctly different between atopic and nonatopic patients (P < 0.001). This study provides evidence that eosinophils and mast cells, both essential to a Th-2 driven immune response, are present in the majority of ears with chronic OME, and supports the hypothesis that middle-ear mucosa, like that of the rest of the upper respiratory tract, is capable of an allergic response.

Adolescent↗

PubMed2001

Microdialysis of histamine in the skin of patients with mastocytosis.

Mastocytosis represents a group of disorders characterized by the proliferation and accumulation of mast cells in tissue. The aim of the present study was to examine whether the interstitial histamine concentration in the skin is increased in mastocytosis patients and whether it correlates with the number of mast cells, the amount of metabolite N-methyl-imidazole acetic acid in the urine and the tryptase in serum. In 7 mastocytosis patients on a standardized diet, the analysis of histamine was performed on microdialysates obtained from catheters positioned intracutaneously in involved and uninvolved skin. N-methyl-imidazole acetic acid in the urine was collected for 24 h. Biopsies for analyses of mast cells were taken from skin adjacent to the microdialysis catheters. The histamine concentrations were 42+/-14, 12+/-3 (P<0.05) and 8+/-2 nmol/l (mean+/-SEM, n=7) in skin eruptions, non-lesional skin and plasma respectively. Mean N-methyl-imidazole acetic acid in the urine (9.7+/-3.5 mmol/mol creatinine) and mean tryptase (124+/-54 microg/l) had increased in all patients. In the present study, no linear correlation was found between these parameters and interstitial histamine in lesional skin. This finding corresponds to the fact that the concentration of histamine metabolites and tryptase derives from the entire mast-cell population, while interstitial histamine in the dermis represents the local tissue concentration before metabolic transformation. The microdialysis of histamine in the skin of mastocytosis patients could be used as a tool to investigate the effects of dermal mast-cell histamine release in different kinds of treatment regimen.

Adolescent↗

PubMed2000

Mast cell subpopulations in chronic inflammatory hepatobiliary diseases.

AIM/BACKGROUND: In various hepatobiliary diseases mast cells have been found to be associated with fibrogenesis. However, mast cell subpopulations have not been investigated in the human liver in normal subjects or in disease. Human mast cells are categorized into mast cells positive for tryptase (MC(T)) only and mast cells positive for both tryptase and chymase (MC(TC)). METHODS: In this study we investigated mast cell subpopulations (MC(T) and MC(TC)) by double immunostaining for mast cell tryptase and chymase as well as by a computer-aided quantitative morphometry in 13 normal livers and in 193 liver tissue specimens comprising of primary biliary cirrhosis (n=43), autoimmune hepatitis (n=11), chronic hepatitis B (n=37), chronic hepatitis C (n=41), alcoholic liver disease (n=40) and hepatolithiasis (n=21). RESULTS: The densities of MC(T) and MC(TC) per 1 mm2 stroma were low in normal livers but high in chronic liver diseases, and correlated positively with the degree of fibrosis. The percentages of MC(T) and MC(TC) subpopulations were 25% and 75%, respectively. The percentage was almost the same in normal livers and various hepatobliliary diseases, as well as between less fibrotic cases and more fibrotic cases in liver diseases. CONCLUSIONS: These results suggest that MC(T) and MC(TC) subpopulations in healthy and diseased livers do not change during liver fibrosis of any etiology.

Adolescent↗

PubMed2000

Agonists of proteinase-activated receptor 2 induce inflammation by a neurogenic mechanism.

Trypsin and mast cell tryptase cleave proteinase-activated receptor 2 and, by unknown mechanisms, induce widespread inflammation. We found that a large proportion of primary spinal afferent neurons, which express proteinase-activated receptor 2, also contain the proinflammatory neuropeptides calcitonin gene-related peptide and substance P. Trypsin and tryptase directly signal to neurons to stimulate release of these neuropeptides, which mediate inflammatory edema induced by agonists of proteinase-activated receptor 2. This new mechanism of protease-induced neurogenic inflammation may contribute to the proinflammatory effects of mast cells in human disease. Thus, tryptase inhibitors and antagonists of proteinase-activated receptor 2 may be useful anti-inflammatory agents.

Animals↗

PubMed2002

Glycosylation of human proteinase-activated receptor-2 (hPAR2): role in cell surface expression and signalling.

We have analysed the role of N-linked glycosylation in regulating human proteinase-activated receptor-2 (hPAR(2)) expression and function. Epitope-tagged wild-type hPAR(2) (wt-hPAR(2)) or hPAR(2) that lacked glycosylation sequons (following site-directed mutagenesis) in either the N-terminus [hPAR(2)N30A (Asn(30)-->Ala)], extracellular loop 2 [ECL2; hPAR(2)N222Q (Asn(222)-->Gln) or hPAR(2)N222A (Asn(222)-->Ala)] or both (hPAR(2)N30A,N222A or hPAR(2)N30A,N222Q) were expressed in the Chinese-hamster ovary (CHO) fibroblast cell line, Pro5. Western blot analysis of wt-hPAR(2) showed mature wt-hPAR(2) to have a molecular mass of 55-100 kDa, and 33-48 kDa following N -glycosidase F deglycosylation. FACS analysis and immunocytochemistry of the wt-hPAR(2) and PAR(2) mutant cell lines revealed that removal of both glycosylation sequons decreases (50% of wt-hPAR(2)) cell surface expression. Western blot analysis indicated that both N-linked sites are glycosylated. In functional studies, hPAR(2)N30A displayed a selective and significant increase in sensitivity towards tryptase. Interestingly, hPAR(2)N222A displayed a loss in sensitivity towards all PAR(2) agonists tested. However, further analysis revealed receptor sensitivity to alanine mutations in this domain, as the more conservative substitution hPAR(2)N222Q displayed no change in response to PAR(2) agonists. hPAR(2)N30A,N222Q displayed increased sensitivity towards tryptase, but a loss in sensitivity towards trypsin and the synthetic peptide SLIGRL-NH(2), although this loss in sensitivity towards trypsin and SLIGRL-NH(2) was secondary to changes in cell-surface expression. Finally, expression of sialic-acid-deficient wt-hPAR(2) in the CHO Lec2 glycosylation-deficient mutant cell line, showed a 40 kDa loss in molecular mass, in addition to a marked and selective increase in sensitivity towards tryptase. We conclude that hPAR(2) N-linked glycosylation and sialylation regulates receptor expression and/or signalling.

Alanine↗

PubMed1997

Loratadine and desethoxylcarbonyl-loratadine inhibit the immunological release of mediators from human Fc epsilon RI+ cells.

BACKGROUND: Loratadine, a novel histamine H1-receptor antagonist, is effective in the treatment of patients with seasonal and perennial rhinitis and some allergic skin disorders. Histamine and other chemical mediators are synthesized and immunologically released by human peripheral blood basophils and tissue mast cells (Fc epsilon RI+ cells). OBJECTIVE: To evaluate the effects of loratadine and its main metabolite, desethoxylcarbonyl-loratadine (des-loratadine), on the immunological release of preformed (histamine and tryptase) and de novo synthesized mediators (leukotriene C4: LTC4 and prostaglandin D2:PGD2) from human Fc epsilon RI+ cells. METHODS: Human Fc epsilon RI+ cells purified from peripheral blood and from skin (HSMC) and lung tissue (HLMC) were preincubated with loratadine and des-loratadine before immunological challenge with Der p 1 antigen or anti-Fc epsilon RI. The release of preformed mediators (histamine and tryptase) and de novo synthesized eicosanoids was evaluated in the supernatants of human Fc epsilon RI+ cells. RESULTS: Preincubation (15 min, 37 degrees C) of purified (36-74%) basophils with loratadine (3 x 10(-6)-10(-4)M) and des-loratadine before Der p 1 antigen or anti-Fc epsilon RI challenge concentration-dependently (5-40%) inhibited the release of histamine and LTC4. Loratadine (3 x 10(-6)-10(-4)M) and des-loratadine also inhibited (10-40%) histamine, LTC4, and PGD2 release from purified HLMC (16-68%) activated by anti-Fc epsilon RI. Loratadine (3 x 10(-6)-10(-4)M) and des-loratadine caused concentration-dependent inhibition (10-40%) of histamine, tryptase, LTC4, and PGD2 release from purified HSMC (24-72%) immunologically challenged with anti-Fc epsilon RI. CONCLUSION: These results indicate that loratadine and its main metabolite have anti-inflammatory activity by inhibiting the release of preformed and de novo synthesized mediators from human Fc epsilon RI+ cells.

Adult↗

PubMed2001

IL-6 attenuates apoptosis, while neither IL-6 nor IL-10 affect the numbers or protease phenotype of fetal liver-derived human mast cells.

BACKGROUND: The combination of recombinant human stem cell factor (rhSCF), rh interleukin (IL)-6 and rhIL-10 was reported to be optimal for mast cell development from cord blood progenitors and to induce chymase expression in all such mast cells earlier in their development than tryptase. OBJECTIVE: The effects of rhIL-6 and rhIL-10 in various combinations on the rhSCF-dependent development of human mast cells from fetal liver progenitors were examined in serum-free media. METHODS: Dispersed fetal liver cells were cultured in serum-free AIM-V medium with rhSCF alone, or with combinations of rhIL-6 and rhIL-10. Tryptase and chymase expression, surface Kit expression, metachromasia with toluidine blue and apoptosis were measured. RESULTS: Neither rhIL-6 nor rhIL-10 nor the two interleukins together, when included from day 0 of culture, affected the number or protease phenotype of mast cells at 1 or 3 weeks. Expression of tryptase paralleled the appearance of metachromasia and surface Kit, both of which preceded chymase expression, regardless whether a rabbit polyclonal or mouse monoclonal anti-chymase antibody preparation was used. On the other hand, rhIL-6 markedly attenuated baseline levels of apoptosis in the presence of rhSCF as well as apoptosis occurring after withdrawal of rhSCF, whereas rhIL-10 had no effect. CONCLUSION: RhIL-6 protected fetal liver-derived mast cells from apoptosis, particularly after withdrawal of rhSCF, but neither rhIL-6 nor rhIL-10 nor the combination of these interleukins affected the numbers or protease phenotype of these mast cells.

Apoptosis↗

PubMed2002

Characterization of 'adult-type' mast cells derived from human bone marrow CD34(+) cells cultured in the presence of stem cell factor and interleukin-6. Interleukin-4 is not required for constitutive expression of CD54, Fc epsilon RI alpha and chymase, and CD13 expression is reduced during differentiation.

BACKGROUND: In vitro-derived human mast cells exhibit different properties, depending in part on the source of progenitor cells. Most investigations have used fetal liver, cord blood or peripheral blood. Few have used adult bone marrow. OBJECTIVE: Human mast cells derived in vitro from the CD34(+) progenitors in bone marrow and cord blood that had been cultured with recombinant human stem cell factor (rhSCF) and recombinant human interleukin-6 (rhIL-6) were compared. METHODS AND RESULTS: After 12 weeks of culture, nearly all of the cells were mast cells, and nearly all of these had cytoplasmic granules containing both tryptase and chymase (MCTC type), stained metachromatically with acidic toluidine blue, and expressed CD117 on the cell surface. Both tryptase protein and mRNA were detected by two weeks of culture. Chymase mRNA and protein were detected at 4 weeks but not at 2 weeks of culture. By 12 weeks, chymase content per cell, measured by ELISA, was significantly higher (P < 0.05) in human bone marrow-derived mast cells (HBMMC) (5.6 +/- 0.9 pg) than in cord blood-derived mast cells (CBMC) (2.4 +/- 0.9 pg), whereas histamine and tryptase levels were not significantly different. Of the cluster designations tested, CD29, CD49d, CD51 and CD61 were strongly expressed on HBMMC. CD54 and Fc epsilon RI alpha also were expressed constitutively. Approximately half of CD34-sorted cells at day 0 were CD13(+) and this diminished as mast cell maturation occurred. Electron microscopy revealed that 12-week-old HBMMC had many secretory granules that contained spherical electron dense cores surrounded by electron lucent space, consistent with previous reports of immature MCTC cells developing in vivo. CONCLUSIONS: CD34(+) progenitors of human bone marrow are a rich source of mast cell progenitors capable of expressing granule and surface markers of mature mast cells in the presence of rhSCF and rhIL-6.

Antigens, CD↗

PubMed2003

Low mast cell density in the human duodenal mucosa from chronic inflammatory duodenal bowel disorders is associated with defective villous architecture.

BACKGROUND: Mast cells (MC) have recently been implicated in the processes of tissue homeostasis, remodeling and repair. DESIGN: In this study, the total and tryptase-reactive mast cell populations were quantified in the duodenal mucosa of 27 subjects suffering from chronic inflammatory bowel disorders. Mast cell density was both related to the general villous architecture (normal or defective) and to the microvascular density in the duodenal mucosa. RESULTS: Total mast cell and tryptase-positive mast cell subpopulation densities were found to be significantly reduced in the samples with defective villous architecture in comparison with those exhibiting a normal villous profile. In these last samples, a relevant proportion of mucosal mast cells exhibited ultrastructural features of secretory activity, in particular piecemeal degranulation. Finally, no correlation was established between microvascular density and tryptase activity, as it has been previously demonstrated in other pathological conditions. CONCLUSIONS: Overall, these findings indicate a significant correlation between mast cell density and the duodenal mucosal architecture.

Adolescent↗

PubMed1999

Mast cell density and subtypes in the skin of Shar Pei dogs with cutaneous mucinosis.

Skin biopsies from 13 Shar Peis showing signs of cutaneous mucinosis and 13 control dogs of different breeds with no clinical or histological evidence of skin disease were examined. One section of each tissue sample was stained with haematoxylin and eosin, and another with toluidine blue to demonstrate the sulphated acid glycosaminoglycans in mast cell (MC) granules. To investigate the MC subtypes involved, the tryptase and chymase content of mast cells was evaluated by a double enzyme-immunohistochemical staining technique. Regardless of the staining technique, a significantly lower mast cell density in the skin of Shar Peis was demonstrated. In the dermis of control dogs, we detected a median mast cell density of 31.2 MC/mm2 using the toluidine blue staining method and 27.5 MC/mm2 using the double labelling technique. In Shar Peis only 9.1 MC/mm2 were found by toluidine blue staining (P = 0.001) and 14.8 MC/mm2 by the double labelling method (P = 0.0387). The percentile distribution of mast cell subtypes was also significantly different in Shar Peis as compared to control dogs. Whereas in the dermis of control dogs the predominant mast cell subtype was the tryptase and chymase containing MC (TC-MC) (60.4%), in Shar Pei skin the only chymase containing MC (C-MC) predominated (62.2%) and the percentage of TC-MC was significantly lower (32.9%; P = 0.0016). The percentage of only tryptase containing MC (T-MC) (4.7%) was higher in Shar Peis compared to control dogs (1.9% P = 0.0178). The data obtained indicate a possible involvement of mast cell subtypes in the pathogenesis of cutaneous mucinosis. Further investigations on the pathophysiological role of mast cell subtypes may foster understanding of the pathogenesis of cutaneous mucinosis.

Animals↗

PubMed2003

Mast cells in the kidney.

Mast cells have become a recent concern in the nephrological world. The development of antibodies to mast cell-specific enzymes, tryptase and chymase, has facilitated the study of mast cells in the kidney. Now, they are investigated immunohistochemically as well as histochemically. There are three types of human mast cells, MC(T), which contains exclusively tryptase, MC(TC), which has both tryptase and chymase, and MC(C), which contains only chymase. Many immunohistochemical studies involving mast cells have been conducted through the use of renal biopsy specimens. As a result, human renal diseases including various glomerulonephritis and pyelonephritis are found to have increased the number of mast cells in the renal cortex, especially in the area of fibrosis. The relationship between the number of mast cells and the prognosis of renal diseases has been proved to be significantly correlated in many reports. The subtypes of mast cells in these diseases are variably present, and no tendency of subtype specificity has been found. With the use of electron microscopically, mast cells are observed to be in contact with other interstitial cells or to infiltrate into tubules. Functionally, human renal mast cells resemble lung mast cells. Inhibitory substances for mast cell proliferation have been found in the mouse kidney. Compared with the results of human studies, mast cells are not found in the interstitum in animal models of renal diseases, except in a few transgenic mouse models and magnesium-deficient rats. Little is known about the exact roles that mast cells play in the renal interstitium. Future studies will hopefully make their characteristics clear.

Animals↗

PubMed2000

Cutaneous malignant melanoma: correlation between neovascularization and peritumor accumulation of mast cells overexpressing vascular endothelial growth factor.

To investigate the possible role of mast cells (MC) in the angiogenic process in cutaneous melanoma, we examined tissue samples from 35 adult patients with primary malignant melanoma and compared with 20 intradermal benign nevi. MC were identified by anti-tryptase, microvessels by anti-CD34, and vascular endothelial growth factor (VEGF) expression by standard immunohistochemical methods. Tryptase-positive MC expressing VEGF were identified by double immunostaining. The numbers of MC and microvessels around the tumor were determined by the point counting method. MC density was significantly greater in melanoma compared with benign nevi (197.6 +/- 19.4 v 95.7 +/- 5.0/mm2, P < .001). Vascular density was also significantly higher in melanoma than in benign lesions (3.6-fold, P < .001). Double immunostaining showed the presence of VEGF in the cytoplasm of tryptase-positive peritumoral MC. The percentage of this MC-subtype was significantly higher in melanoma than in nevus tissues (71.9 +/- 2.4% v 30.6 +/- 2.5%, P < .001). A strong significant correlation was shown between the number of VEGF+ MC and microvessel density (r = .811, P < .001). MC count and VEGF+ MC count, as well as microvessel density were significantly higher in aggressive (metastasizing) melanomas (P < .001). Our results suggest that peritumoral accumulation of MC and the subsequent release of potent angiogenic factor such as VEGF may thus represent a tumor-host interaction that may favor progression of this tumor.

Adolescent↗

PubMed2001

Immunohistochemical properties of bone marrow mast cells in systemic mastocytosis: evidence for expression of CD2, CD117/Kit, and bcl-x(L).

In an attempt to identify novel diagnostic markers for mast cell (MC)-proliferative disorders, serial bone marrow (bm) sections of 22 patients with mastocytosis (systemic indolent mastocytosis, n = 19; mast cell leukemia [MCL], n = 1; isolated bm mastocytosis, n = 2) were analyzed by immunohistochemistry using antibodies against CD2, CD15, CD29, CD30, CD31, CD34, CD45, CD51, CD56, CD68R, CD117, HLA-DR, bcl-2, bcl-x(L), myeloperoxidase (MPO), and tryptase. Staining results revealed expression of bcl-x(L), CD68R, and tryptase in neoplastic MCs (focal dense infiltrates) in all patients. Mastocytosis infiltrates were also immunoreactive for CD45, CD117 (Kit), and HLA-DR. In most cases, the CD2 antibody produced reactivity with bm MCs in mastocytosis, whereas in control cases (reactive bm, immunocytoma, myelodysplastic syndrome), MCs were consistently CD2 negative. Expression of bcl-2 was detectable in a subset of MCs in the patient with MCL, whereas no reactivity was seen in patients with SIM or bm mastocytosis. Mastocytosis infiltrates did not react with antibodies against CD15, CD30, CD31, CD34, or MPO. In summary, our data confirm the diagnostic value of staining for tryptase, Kit, and CD68R in mastocytosis. Apart from these, CD2 may be a novel useful marker because MCs in mastocytosis frequently express this antigen, whereas MCs in other pathologic conditions are CD2 negative.

Adolescent↗

PubMed2004

Activated mast cells in proximity to colonic nerves correlate with abdominal pain in irritable bowel syndrome.

BACKGROUND & AIMS: The mechanisms underlying abdominal pain perception in irritable bowel syndrome (IBS) are poorly understood. Intestinal mast cell infiltration may perturb nerve function leading to symptom perception. We assessed colonic mast cell infiltration, mediator release, and spatial interactions with mucosal innervation and their correlation with abdominal pain in IBS patients. METHODS: IBS patients were diagnosed according to Rome II criteria and abdominal pain quantified according to a validated questionnaire. Colonic mucosal mast cells were identified immunohistochemically and quantified with a computer-assisted counting method. Mast cell tryptase and histamine release were analyzed immunoenzymatically. Intestinal nerve to mast cell distance was assessed with electron microscopy. RESULTS: Thirty-four out of 44 IBS patients (77%) showed an increased area of mucosa occupied by mast cells as compared with controls (9.2% +/- 2.5% vs. 3.3 +/- 0.8%, respectively; P < 0.001). There was a 150% increase in the number of degranulating mast cells (4.76 +/- 3.18/field vs. 2.42 +/- 2.26/field, respectively; P = 0.026). Mucosal content of tryptase was increased in IBS and mast cells spontaneously released more tryptase (3.22 +/- 3.48 pmol/min/mg vs. 0.87 +/- 0.65 pmol/min/mg, respectively; P = 0.015) and histamine (339.7 +/- 59.0 ng/g vs. 169.3 +/- 130.6 ng/g, respectively; P = 0.015). Mast cells located within 5 microm of nerve fibers were 7.14 +/- 3.87/field vs. 2.27 +/- 1.63/field in IBS vs. controls (P < 0.001). Only mast cells in close proximity to nerves were significantly correlated with severity and frequency of abdominal pain/discomfort (P < 0.001 and P = 0.003, respectively). CONCLUSIONS: Colonic mast cell infiltration and mediator release in proximity to mucosal innervation may contribute to abdominal pain perception in IBS patients.

Abdominal Pain↗

PubMed2002

Effects of rhinovirus-induced common colds on granulocyte activity in allergic rhinitis.

OBJECTIVE: To explore the activities of mast cells, eosinophils, and neutrophils in patients with allergic rhinitis developing common colds and increased responsiveness to allergen following nasal rhinovirus inoculation. METHODS: We have revisited a nasal lavage material obtained from 17 patients who were successfully inoculated with rhinovirus outside the pollen season and received nasal allergen challenges before and after inoculation. We have examined indices of mast cell activity (tryptase), eosinophil degranulation (eosinophil peroxidase; EPO), and neutrophil activation (myeloperoxidase; MPO). RESULTS: Allergen challenges performed before rhinovirus inoculation increased the nasal output of EPO. Notably, this response was significantly greater after rhinovirus inoculation (cf. before inoculation). The output of MPO was also increased following allergen challenge after, but not before, rhinovirus inoculation. Nasal lavage fluid levels of tryptase were increased following allergen challenge similarly before and after rhinovirus inoculation. Also, the viral infection did not affect the baseline levels of tryptase. CONCLUSIONS: The present data demonstrate that rhinovirus infections activate both eosinophils and neutrophils, but that they may not affect mast cell activity. We suggest that common colds in part through stimulation of granulocyte activity potentiate the airway inflammation in allergic diseases.

Administration, Intranasal↗

PubMed2001

Patients still reacting to a sting challenge while receiving conventional Hymenoptera venom immunotherapy are protected by increased venom doses.

BACKGROUND: Up to 20% of patients allergic to Hymenoptera venom are not protected by conventional venom immunotherapy (VIT) with 100 microg of any single venom. OBJECTIVE: We sought to evaluate the efficacy of an increased venom dose in patients allergic to Hymenoptera venom still reacting systemically to a sting challenge despite immunotherapy with 100 microg of venom every 4 weeks. METHODS: In this retrospective study patients were included who still had reacted systemically to a sting challenge with a living bee or wasp despite VIT with a maintenance dose of 100 microg every 4 weeks. The maintenance dose was increased to 150 or 200 microg every 4 weeks, and a second sting challenge was performed. If a patient reacted again, the dose was further increased. Baseline mast-cell tryptase levels were assessed by using a fluoroenzyme immunoassay in stored patient sera. RESULTS: While receiving a maintenance dose of 100 microg of venom every 4 weeks for 7 to 38 months, 18 patients reacted systemically to a bee sting and 22 reacted to a wasp sting. After an increase of the maintenance dose to 150 microg, 2 of 4 patients allergic to bee venom (BV) and 6 of 6 patients allergic to yellow jacket venom (YJV) no longer reacted systemically to the sting challenge. The respective rates of full protection were 13 of 14 and 15 of 16 in patients with an increase of the maintenance dose to 200 microg from the start. Of those 4 individuals not protected by the first dose increase, one patient allergic to BV (prior dose of 150 microg) and one patient allergic to YJV (prior dose of 200 microg) did not react systemically to a further sting challenge while receiving 200 microg of BV or 250 microg of YJV, respectively. One patient allergic to BV who had a systemic reaction to the sting challenge while receiving 150 microg was not protected after a dose increase to 200 microg; she later received a dose of 400 microg of BV, and no further sting challenge was performed. The patient allergic to BV who still reacted systemically after a first dose increase to 200 microg was a female patient with urticaria pigmentosa. She had repeated systemic adverse reactions to further BV immunotherapy, necessitating discontinuation of the treatment; however, she tolerated well VIT with 200 microg of YJV. In all other patients, no unusual adverse reactions to the increased venom doses were observed. Baseline serum tryptase levels were elevated above 13.5 microg/L (95th percentile in normal subjects) in 9 (28.1%) of 32 patients. CONCLUSIONS: The majority of patients allergic to Hymenoptera venom who still reacted systemically to a sting challenge despite VIT with a dose of 100 microg every 4 weeks can be fully protected by an increased maintenance dose. This dose increase is well tolerated by most patients. The rather high proportion of patients with elevated baseline serum tryptase levels necessitates further investigation of a possible association between mastocytosis and treatment failure of conventionally dosed VIT.

Adult↗

PubMed2003

A controlled study of 9alpha,11beta-PGF2 (a prostaglandin D2 metabolite) in plasma and urine of patients with bronchial asthma and healthy controls after aspirin challenge.

BACKGROUND: Prostaglandin D(2) (PGD(2)) is the predominant cyclooxygenase product of mast cells, the number of which is increased in bronchial asthma. Release of PGD(2) might reflect mast cell activation and disordered function of the asthmatic lung. OBJECTIVE: We sought to determine blood and urinary levels of 9alpha,11beta-PGF(2), a major stable PGD(2) metabolite in 2 well-defined phenotypes of asthma, aspirin-induced asthma (AIA) and aspirin-tolerant asthma (ATA), and in healthy control subjects and to study the effects of aspirin on PGD(2) release. METHODS: Using gas chromatography/mass spectrometry, we determined plasma and urinary concentrations of 9alpha,11beta-PGF(2) at baseline in 131 stable asthmatic patients, 65 of whom had AIA and 66 of whom had ATA. Fifty healthy nonatopic subjects served as the control group. The measurements were also performed after an aspirin challenge in 26 of 65 patients with AIA and in 24 of 50 control subjects. RESULTS: At baseline, patients with AIA had significantly higher plasma levels of 9alpha,11beta-PGF(2) than either patients with ATA or healthy subjects. A similar significant elevation of serum tryptase was observed in patients with AIA compared with patients with ATA and control subjects. Mean urinary 9alpha,11beta-PGF(2) values did not differ among the 3 groups. In patients with AIA, as opposed to healthy subjects, aspirin challenge invariably precipitated a clinical reaction, accompanied in most patients by a further rise in plasma levels of PGD(2) metabolite and tryptase. CONCLUSIONS: In stable AIA, though not in ATA, there is a steady release of PGD(2) into the blood, accompanied by the release of tryptase. Aspirin enhances this reaction in most patients. Release of bronchoconstrictive PGD(2) might contribute to the severe clinical course of AIA.

Adult↗

PubMed1997

Residual cytotoxicity and granzyme K expression in granzyme A-deficient cytotoxic lymphocytes.

Cytotoxic lymphocytes contain granules that have the ability to induce apoptosis in susceptible target cells. The granule contents include perforin, a pore-forming molecule, and several granzymes, including A and B, which are the most abundant serine proteases in these granules. Granzyme B-deficient cytotoxic T lymphocytes (CTL) have a severe defect in their ability to rapidly induce apoptosis in their targets, but have an intact late cytotoxicity pathway that is in part perforin-dependent. In this report, we have created mice that are deficient for granzyme A and characterized their phenotype. These mice have normal growth and development and normal lymphocyte development, activation, and proliferation. Granzyme A-deficient CTL have a small but reproducible defect in their ability to induce 51Cr and 125I-UdR release from susceptible allogeneic target cells. Since other granzyme A-like tryptases could potentially account for the residual cytotoxicity in granzyme A-deficient CTL, we cloned the murine granzyme K gene, which is linked to granzyme A in humans, and proved that it is also tightly linked with murine granzyme A. The murine granzyme K gene (which encodes a tryptase similar to granzyme A) is expressed at much lower levels than granzyme A in CTL and LAK cells, but its expression is unaltered in granzyme A-/- mice. The minimal cytotoxic defect in granzyme A-/- CTL could be due to the existence of an intact, functional early killing pathway (granzyme B dependent), or to the persistent expression of additional granzyme tryptases like granzyme K.

Amino Acid Sequence↗