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PubMed1991

Tryptase in nasal lavage fluid after local allergen challenge. Relationship to histamine levels and TAME-esterase activity.

The activation of mast cells is generally considered to be an important trigger mechanism in the immediate allergic response. This study focused on the determination of three markers of mast cell activation after an allergen challenge. Nasal allergen challenges were performed in 25 subjects with seasonal allergic rhinitis using three allergen doses increasing in 10-fold steps in a standardised nasal lavage model for the subsequent recovery of the markers of mast cell activation. The levels of histamine and tryptase in the nasal lavage fluid were determined using radioimmunoassays, while the TAME-esterase activity was determined using a radiochemical technique. The nasal symptoms obtained on challenge were assessed using a scoring technique. The allergen challenge resulted in significant increases in the levels of all three markers, tryptase, histamine and TAME-esterase. In the individual measurements after the challenges there was a highly significant correlation between the TAME-esterase levels and the tryptase levels (r = 0.71; P less than 0.001), while the generation of histamine and tryptase was not significantly correlated. When comparing the cumulative generation of the three markers, significant correlations were found between all three. Allergen challenges in six non-allergic controls using the same technique did not result in any increase in tryptase levels. The findings suggest that the determination of tryptase in nasal lavage fluid may be a valuable indicator of mast cell activation in the upper airways.

Adult↗

PubMed1988

Activation of pulmonary mast cells by bronchoalveolar allergen challenge. In vivo release of histamine and tryptase in atopic subjects with and without asthma.

Human mast cells likely play a significant role in human asthma. In the present study, concentrations of tryptase and histamine in bronchoalveolar lavage fluid (BALF) were used as indicators of pulmonary mast cell activation. BALF was obtained before and after endobronchial allergen challenge and assessed for mediator content and cell composition in 4 subject groups: nonatopic nonasthmatics (Group 1, n = 7), nonatopic asthmatics (Group 2, n = 3), atopic nonasthmatics (Group 3, n = 7), and atopic asthmatics (Group 4, n = 7). Before challenge, histamine concentrations were not different between the 4 groups, whereas tryptase concentrations were significantly greater in the atopic asthmatics than in each of the other groups (p less than 0.04). Allergen challenge in atopic asthmatics resulted in significant increases above baseline in mean +/- SD histamine (0.7 +/- 7.1 to 2.8 +/- 2.0 ng/ml) and tryptase (2.0 +/- 1.7 to 10.1 +/- 8.2 ng/ml) concentrations in BALF (p less than 0.03). Atopic nonasthmatics also had increases above baseline in histamine (0.2 +/- 0.2 to 1.2 +/- 1.4 ng/ml) and tryptase (0.5 +/- 0.4 to 1.4 +/- 1.03 ng/ml) concentrations after allergen challenge (p less than 0.05). Though the histamine values were not significantly different between atopic nonasthmatics and atopic asthmatics after allergen challenge, tryptase concentrations were markedly higher in the atopic asthmatic group. The numbers, as well as the predominance of the T mast cell type in atopic asthmatics and nonasthmatics, were no different from controls. In nonatopic subjects, regardless of asthmatic state, histamine or tryptase concentrations were not altered by allergen challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Mast cell tryptase causes airway smooth muscle hyperresponsiveness in dogs.

Supernatants obtained by degranulation of dog mastocytoma cells greatly increased the sensitivity and the magnitude of the contractile response of isolated dog bronchial smooth muscle to histamine. The enhanced contractile response was reversed completely by H1-receptor antagonists and was prevented by an inhibitor of tryptase (a major protease released with histamine from secretory granules of mast cells). The potentiation of histamine-induced contractions was reproduced by active tryptase in pure form. The contractions due to the combination of histamine and purified tryptase were abolished by the Ca2+ channel blockers nifedipine and verapamil. The bronchoconstricting effects of KCl and serotonin, which, like histamine, contract airway smooth muscle by a mechanism predominantly involving membrane potential-dependent Ca2+ transport, were also potentiated by tryptase. However, the contractile effects of acetylcholine, which contracts dog airway smooth muscle by a mechanism independent of Ca2+ channels, were unaffected by tryptase. These findings show a striking promotion of agonist-induced bronchial smooth muscle contraction by mast cell tryptase, via direct or indirect effects on Ca2+ channels, and the findings therefore suggest a novel potential mechanism of hyperresponsiveness in dog bronchi.

Airway Resistance↗

PubMed1989

Synovial procollagenase activation by human mast cell tryptase dependence upon matrix metalloproteinase 3 activation.

Mast cells have been implicated in the pathogenesis of the matrix degradation observed in the cartilaginous and osseous structures of the rheumatoid joint. We previously reported that human mast cell tryptase, a 134-kD granule-associated neutral protease, is present in rheumatoid synovium and can activate collagenase in crude culture medium in vitro. the present study attempts to depict the precise mechanism of this activation. To express full activation of latent collagenase, matrix metalloproteinase 3 (MMP-3) or stromelysin, can be activated by tryptase in a time and dose-dependent manner. Tryptase was not capable of generating active collagenase in the crude media from cultured rheumatoid synoviocytes depleted of proMMP-3 by immunoadsorption. In addition, the function of the tissue inhibitor of metalloproteinases (TIMP) was not altered by tryptase, and SDS-PAGE analysis revealed no degradation of TIMP by tryptase. The tryptase dependent activation of synoviocyte procollagenase thereby appears to be entirely dependent upon its ability to activate proMMP-3.

Blotting, Western↗

PubMed1989

Enzyme histochemical discrimination between tryptase and chymase in mast cells of human gut.

We tested four synthetic substances for their histochemical value to demonstrate the catalytic activities of chymase or tryptase in mast cells in sections of human gut. Both Suc-Ala-Ala-Phe-4 methoxy-2-naphthylamide (MNA) and N-acetyl-L-methionine-alpha-naphthyl ester (alpha-N-O-Met) reacted with chymase but not tryptase in mast cells. Conversely, D-Val-Leu-Arg-MNA and Z-Ala-Ala-Lys-MNA were hydrolyzed by mast cell tryptase but not chymase. These results were confirmed by use of two inhibitors of chymotrypsin-like activity, chymostatin and Z-Gly-Leu-Phe-chloromethyl ketone (CK) and two inhibitors of trypsin-like activity, Tos-Lys-CK and D-Val-Leu-Arg-CK. Excellent staining reactions were obtained on cryostat sections of unfixed or aldehyde-fixed tissues and on paraffin sections of Carnoy-fixed tissues. For chymase, however, Suc-Ala-Ala-Phe-MNA is preferred on cryostat sections because it is more specific. On paraffin sections alpha-N-O-Met is preferred because other cells are not then stained. For tryptase, Z-Ala-Ala-Lys-MNA was more selective and more specific and is the preferred general purpose substrate on cryostat sections of aldehyde-fixed tissues and for paraffin sections. D-Val-Leu-Arg-MNA is the preferred substrate for cryostat sections of unfixed tissue. Only a limited number of mast cells showed a reaction for chymase, and these occurred mainly in the submucosa. All mast cells, however, gave a reaction for tryptase, and we recommend the use of either substrate for this enzyme for routine detection of mast cells in human tissues. Double staining for the two main mast cell proteases is most conveniently undertaken on paraffin sections of Carnoy-fixed tissues using MNA substrates for tryptase and alpha-N-O-Met for chymase.

2-Naphthylamine↗

PubMed1991

Quantitation of tryptase- and chymase-containing mast cells in cutaneous lichen planus.

The distribution and density of tryptase- and chymase-positive mast cells in lesional and non-lesional cutaneous lichen planus (LP) was analysed. For this, enzyme-histochemical staining techniques and morphometrical measurements were applied. In non-lesional LP skin, chymase-positive cells (TC mast cells) showed a distribution similar to that found in both non-lesional psoriatic skin and in normal skin. Tryptase-positive cells (reflecting both T and TC mast cells), however, were increased in number in the upper dermis of non-lesional LP skin. In lesional LP skin, there were fewer chymase-positive cells in the upper dermis, whereas there were more tryptase-positive cells. In the upper dermis, no differences in the number of tryptase containing cells were detected between lesional and nonlesional LP skin. In lesions of LP and psoriasis, tryptase-positive mast cells are increased but differ in their distribution in the papillary dermis. In psoriatic lesions, tryptase-positive cells are frequently observed in epidermal contact, a feature very rarely seen in LP lesions. The present results suggest that the increased numbers of T mast cells in the upper dermis of nonlesional LP skin may be involved in initiating the LP lesion. It seems unlikely that mast cells could be responsible for the epidermal basal cell damage, though T mast cells do participate in the general inflammatory reaction.

Adult↗

PubMed1981

Tryptase from human pulmonary mast cells. Purification and characterization.

Tryptase, the predominant neutral protease in human mast cell secretory granules, was purified to homogeneity from dissociated and concentrated pulmonary mast cells by sequential chromatography on Dowex 1-X2, DEAE-Sephadex, and heparin-agarose. Purified tryptase gave a single stained protein band on polyacrylamide gels after electrophoresis at pH 4.3 in the presence of 4 M urea. The enzyme has an apparent molecular weight of 120,000 to 140,000 by gel filtration chromatography. Electrophoresis of purified tryptase under denaturing conditions revealed subunits with molecular weights of 37,000 and 35,000 in a molar ratio of 1:1, consistent with a tetrameric subunit structure for the holoenzyme of Mr = 144,000. Both subunits bind [3H]diisopropyl fluorophosphate as assessed by the correspondence of radioactivity with the two stained protein bands in a polyacrylamide gel after electrophoresis of purified tryptase under denaturing conditions, indicating that all four subunits of the holoenzyme may have active site capacity. Purified tryptase has a specific activity for tosyl-L-arginine methyl ester of 97 units/mg (1 unit = 1 mumol of substrate cleaved/min at 22 degrees C). Human pulmonary mast cells contain tosyl-L-arginine methyl ester-esterase at levels more than 100-fold higher than those of human neutrophils, eosinophils, and monocytes. One million mast cells contain about 1.1 units, or 6 to 19 micrograms of tryptase, and have the capacity to contribute dominant levels of this enzyme at tissue sites of mast cell degranulation.

Amino Acids↗

PubMed1994

Close co-localization of CD4 and a serine esterase tryptase TL2 on the cell-surface of human monocytoid and CD4+ lymphoid cells.

Tryptase TL2, a serine esterase in the membrane of human monocytoid and CD4+ lymphoid cells, specifically binds to the V3 domain of HIV-1 gp120. Here we report that monoclonal antibodies against CD4 that recognize the epitope interacting with gp120 specifically blocked the immunostaining of cell-surface tryptase TL2, although the antibody does not cross-react with tryptase TL2. Down-regulation of cell-surface CD4 induced by HIV-1 Nef prevented this blocking effect. These data suggest that CD4 is closely co-localized with tryptase TL2 on the cell surface and that regulation of the expression of tryptase TL2 is not associated with that of CD4.

Antibodies, Monoclonal↗

PubMed1997

[Cisatracurium--is the stereoisomer an "ideal" relaxant? Histamine liberation and tryptase determination after bolus administration of cistracurium: a comparison with vecuronium].

UNLABELLED: Cisatracurium (51W89, Nimbex, Glaxo-Wellcome), an intermediate-acting non-depolarizing neuromuscular blocking agent, is a stereoisomer of atracurium. Histamine releasing propensities and serum tryptase level have been investigated after administration of cisatracurium (3 x ED95, 5 x ED95) or vecuronium (3 x ED90) in surgical patients. METHODS: After approval by our institutional review board, 62 patients (ASA I-II) were randomly assigned to three groups to receive either 3 x ED95 or 5 x ED95 cisatracurium, or 3 x ED90 vecuronium as a rapid bolus. A prick test was done the day before by scarification of the skin in the forearm. After premedication with 2 mg lormetazepam, anaesthesia was induced with thiopentone (4-12 mg/kg) and maintained with O2/N2O and isoflurane (1.5-2 vol.%). Six minutes after thiopentone, the patients received the relaxant and after further 6 min 0.1-0.2 mg fentanyl was given and the trachea was intubated. Heart rate (HR) and blood pressure (BP) were monitored every minute. Blood samples for histamine were withdrawn 5 min prior 3 and 5 min after each drug administration (thiopentone, relaxants). Plasma histamine was measured by radioimmunoassay (RIA) with a sensitivity of approximately 10 pg/ml. Additionally, serum tryptase was measured by RIA at baseline (-10 and -1 min) and 15 and 60 min after the relaxant administration. Levels for histamine > 1000 pg/ml and for tryptase > 2 micrograms/ml were considered significant. Cutaneous signs of histamine release were documented. RESULTS: Ten patients showed a positive prick-test reaction. Only after thiopentone some cutaneous signs (4 flush, 1 erythema) of histamine release were observed. There were no cutaneous signs of histamine release correlating with cardiovascular changes. Analysis of the blood samples demonstrated no significant increase in the histamine level in all three groups. Only in 1 patient was a significant higher histamine level (1133 pg/ml) measured 5 min after 5 x ED95 cisatracurium. All measurements of serum tryptase were within the physiological limits. DISCUSSION: In this study, with the particular time course of drug administration, neither cisatracurium nor vecuronium increased plasma histamine levels. Only after 5 x ED95 cisatracurium was 1 elevated histamine level documented after 5 min. In several studies increased histamine levels have been described, but without clinical manifestations. It is known that cutaneous signs can occur without increased plasma histamine levels due to the structural heterogeneity of mast cells. The cutaneous reactions in this study were caused by thiopentone. The tryptase values were within normal limits even in the patient with histamine release. No relationship between the positive results in the prick test and the incidence of cutaneous reactions and/or histamine release for drugs used in the induction of anaesthesia was observed. Whether cisatracurium has a potential for immunologic release is unknown.

Anesthesia, Intravenous↗

PubMed1999

Serum tryptase: an indicator of anaphylaxis following fluorescein angiography.

BACKGROUND: Anaphylaxis is a potentially fatal complication of fluorescein angiography. It is diagnosed by clinical signs. Serum beta-tryptase serves as a specific indicator of mast cell activation and of anaphylactic shock that can be detected by radioimmunoassay. METHOD: This is a report on a 48-year-old woman who developed anaphylaxis during fluorescein angiography. This study investigates the role of beta-tryptase in anaphylactic shock resulting from intravenous fluorescein angiogram. RESULTS: A serum sample of beta-tryptase collected at the time of an adverse reaction to fluorescein angiography was determined by radioimmunassay to be elevated above 20 ng/ml (normal level <1 ng/ml). This indicates massive mast cell activation and anaphylactic shock. CONCLUSION: This case is the first in which elevated levels of beta-tryptase in serum indicated that the systemic adverse reaction to fluorescein was mast cell dependent. Additionally, beta-tryptase levels can be assayed to detect anaphylactic reactions several hours after a precipitating event.

Anaphylaxis↗

PubMed1995

Detection of tryptase TL2 and CD26 antigen in brain-derived cells non-permissive to T-cell line-tropic human immunodeficiency virus type 1.

Tryptase TL2 purified from MOLT-4 human T cells binds to the envelope protein of human immunodeficiency virus type 1 (HIV-1). Tryptase TL2 and CD26 antigen are supposed to play roles in HIV-1 entry into cells. Although CD4 is a principal receptor for HIV-1, brain cells expressing the CD4 antigen are not permissive to HIV-1 strains infectious to monocyte or T-cell lines. We examined whether the non-permissiveness of the brain-derived cells to standard HIV-1 strains could be explained by a lack of tryptase TL2 or CD26. Western blots showed that the amounts of tryptase TL2 expressed in cell lysates prepared from the brain-derived cells were similar to those prepared from various cells susceptible to HIV-1 strains. Furthermore, flow cytometry revealed the presence of the CD26 antigen on the cell surface of many types of cells. The resistance of the brain-derived cells to standard HIV-1 strains is not due to a lack of tryptase TL2 or CD26.

Brain↗

PubMed2003

Inhibition of dipeptidyl peptidase I in the human mast cell line HMC-1: blocked activation of tryptase, but not of the predominant chymotryptic activity.

The mast cell proteases tryptase and chymase are synthesised as inactive precursors, but are stored and secreted as active enzymes. The cysteinyl protease dipeptidyl peptidase I (DPPI, cathepsin C) can activate the corresponding proenzymes in cell-free systems, but it is unknown whether it fulfils this role within the intact cell. We, therefore, tested the effect the DPPI-selective inhibitor Gly-Phe diazomethyl ketone (Gly-Phe-CHN(2)) on the tryptic and chymotryptic activity of the human mast cell-like cell line, HMC-1, and monitored any changes in the amount of immunodetectable enzymes by flow cytometry. Culture in Gly-Phe-CHN(2) produced a significant decrease in tryptase activity in cell lysates within 24hr and further decreases during continued culturing to 216 hr with periodic replenishment of Gly-Phe-CHN(2)-containing media. Flow cytometry showed no significant change in the levels of immunoreactive tryptase. In contrast, chymotryptic activity in treated cells did not differ significantly from untreated cells at any time point. Treatment of 216 hr cell lysates with DPPI revealed significant amounts of activatable protryptase in Gly-Phe-CHN(2)-treated cells, but not in controls, whereas activatable prochymotryptic activity was found in both treated and control cells. Chymase was detected immunologically, though small differences in substrate specificity and molecular mass were observed. These results strongly suggest that DPPI plays a role in the activation of tryptase, but not of the predominant chymotryptic activity of HMC-1 cells. As inhibitors of tryptase have proven efficacious in models of allergic disease, these results also indicate that inhibitors of DPPI might provide an additional point of therapeutic control.

Animals↗

PubMed2006

Oral antihistamine therapy influences plasma tryptase levels in adult atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is an allergic skin disease that follows a clinical course of 'flare-up' and remission. Histamine and tryptase are inducers of pruritus and non-sedating second-generation antihistamines, including fexofenadine, are widely used for treatment of allergic skin disorders. OBJECTIVE: We assessed the efficacy of a second-generation antihistamine in AD patients and examined its pharmacological effects on chemical mediators. METHODS: The scoring atopic dermatitis (SCORAD) instrument and visual analogue scale (VAS) for pruritus were used to assess disease severity in 349 AD patients. Twenty patients with moderate AD symptoms, who had not received any treatment for 2 weeks, were randomly assigned into two groups. Ten patients underwent fexofenadine and emollient treatment (Group 1) and 10 received fexofenadine and steroid treatment (Group 2) for 1 week. SCORAD and VAS for pruritus, and blood histamine and tryptase levels were evaluated before and after treatment. RESULTS: SCORAD and VAS improved in both Group 1 (p=0.01 and p=0.006, respectively) and Group 2 (p<0.001 and p=0.001, respectively). The improvement in Group 1 showed a significant correlation with the diminution rate of blood tryptase levels (SCORAD: r=0.83 and p=0.013, respectively; VAS: r=0.81, p=0.015, respectively). End-point plasma tryptase levels were significantly lower than baseline levels in Group 2 (p=0.046). Histamine levels did not show any significant changes in either group. CONCLUSION: These results suggest that second-generation antihistamine therapy reduces AD pruritus, resulting in the effective clinical treatment for AD. In addition, monitoring tryptase levels during antihistamine therapy in moderate AD treatment may prove to be useful in establishing treatment effects.

Administration, Oral↗

PubMed2003

The inhibition of mast cell activation by neutrophil lactoferrin: uptake by mast cells and interaction with tryptase, chymase and cathepsin G.

Inhibitors of mast cell tryptase and chymase can be effective as mast cell stabilising compounds. Lactoferrin has been reported to inhibit tryptase activity, but its actions on other serine proteases of mast cells and its potential to alter mast cell function are not known. We have examined the ability of lactoferrin to inhibit mast cell tryptase, chymase and cathepsin G, and investigated its potential to modulate the activation of human mast cells. Enzymatically dispersed cells from human skin, lung and tonsil were challenged with anti-IgE or calcium ionophore A23187, following incubation with recombinant human lactoferrin, and histamine release determined. IgE-dependent histamine release from skin mast cells was inhibited by up to 50% following incubation with lactoferrin (50 or 500 nM). Tonsil mast cells were also stabilised by lactoferrin, but not those from lung. Calcium ionophore A23187-induced histamine release was not altered by lactoferrin. A double-labelling immunocytochemical procedure revealed the presence of lactoferrin in 4-6% of mast cells, and this proportion increased to 40% following incubation with lactoferrin. Lactoferrin did not inhibit cleavage of synthetic substrates by tryptase and chymase directly, though it was able to diminish the ability of heparin to stabilise tryptase. Cathepsin G activity was inhibited by lactoferrin. The ability of lactoferrin to inhibit IgE-dependent activation of human mast cells and modulate protease activity suggests that the release of this neutrophil product may have a role in the downregulation of allergic inflammation.

Cathepsin G↗

PubMed2001

The activation of synovial mast cells: modulation of histamine release by tryptase and chymase and their inhibitors.

Mast cells have been implicated as having pivotal roles in arthritis, but little is known of the processes leading to the activation of synovial mast cells or their potential for pharmacological control. We have investigated the ability of tryptase and chymase, and inhibitors of these major mast cell proteases to modulate the activation of mast cells from human synovial tissue. The tryptase inhibitor drug N-(1-hydroxy-2-naphthoyl)-L-arginyl-L-prolinamide hydrochloride (APC366) inhibited immunoglobulin E (IgE)-dependent histamine release in a dose-dependent manner, with about 70% inhibition being achieved at a dose of 300 microM. Histamine release stimulated by calcium ionophore A23187 was also inhibited by this compound. The chymase inhibitor chymostatin inhibited IgE-dependent histamine release by approximately 60% at 1 microg/ml. Tryptase at concentrations of 3.0 microg/ml and greater stimulated histamine release from synovial cells, which was dependent on catalytic activity, whereas chymase had little effect on these cells. The activation of mast cells by tryptase may represent an amplification process in the synovium. The mast cell stabilising properties of inhibitors of tryptase and chymase could be of therapeutic value in arthritis.

Calcimycin↗

PubMed1999

The effect of short-term immunotherapy with molecular standardized grass and rye allergens on eosinophil cationic protein and tryptase in nasal secretions.

BACKGROUND: Activation of mast cells and eosinophils under pollen exposure can be inhibited by specific immunotherapy. OBJECTIVE: The effect of short-term immunotherapy with 7 preseasonal injections of molecular standardized allergens from grass and rye pollen on eosinophil cationic protein (ECP) and tryptase levels in nasal secretions has been compared with symptomatic drug treatment in an open, randomized study with 48 patients. METHODS: Nasal reactivity and mediator levels in nasal secretions were measured at baseline, before season, in season, and after season. RESULTS: Symptom scores in the immunotherapy group were 134.5 (95% CI, 65 to 336) versus 386. 0 (95% CI, 185 to 563), significantly lower as in the drug-treated group. ECP and tryptase levels increased significantly during natural allergen exposition. The seasonal levels in the immunotherapy group were significantly lower than in the drug-treated group with 272.1 ng/mL (252.0 to 293.9 ng/mL; immunotherapy) versus 470.4 ng/mL (SEM, 435.6 to 508.0 ng/mL; drugs) for ECP and with 8.73 ng/mL (SEM, 8.20 to 9.29 ng/mL) versus 17.47 ng/mL (16.42 to 18.60 ng/mL) for tryptase (all, P <.001). The ECP level induced by nasal provocation was 105.6 ng/mL (99.0 to 112.6 ng/mL) versus 180.4 ng/mL (169.2 to 192.4 ng/mL), significantly lower (P <.001) in the immunotherapy group, as was the tryptase level with 12.12 ng/mL (11.53 to 12.75 ng/mL) versus 8.19 ng/mL (7. 79 to 8.62 ng/mL; P <.001) at the after-season visit. CONCLUSION: Short-term immunotherapy is able to reduce tryptase and ECP in nasal secretions more effectively than drug treatment in patients with allergic rhinitis.

Adolescent↗

PubMed1998

Structural and functional properties of Bos taurus tryptase: a search for a possible propeptide processing role.

Some structural features of bovine tryptase were discussed based on spectroscopic analysis. The far UV-CD spectrum of the enzymatically active bovine tryptase is consistent with a structure containing very little, if any alpha-helix, as found for other serine proteases. The analysis of near UV-CD and UV absorption spectra reveals the presence of a high number of Trp residues arranged probably in strong structural motifs. At variance with other tryptases, the bovine enzyme shows an electrophoretic behaviour in native and denaturating conditions compatible with an association state larger than a tetramer (probably a dodecamer). From a biochemical point of view, the bovine tryptase shares with the human counterpart, the preference for cleaving substrates bearing dibasic cleavage sites. Thus, it is hypothesized that tryptase may be involved in some proprotein processing mechanism(s).

Amino Acid Sequence↗

PubMed1993

Heterogeneity of mast cells at multiple body sites. Fluorescent determination of avidin binding and immunofluorescent determination of chymase, tryptase, and carboxypeptidase content.

Human mast cells (MCs) from multiple sites were studied to determine heterogeneity of expression of chymase, tryptase, and/or carboxypeptidase and the binding to avidin. Three immunophenotypes were found: MCs positive for tryptase (MCT), no immunodetectable chymase; MCs positive for tryptase and chymase (MCTC); and MCs positive for chymase (MCC), no immunodetectable tryptase. Chymase-positive MCs also bound avidin and contained carboxypeptidase. In breast skin and parenchyma and axillary lymph nodes > 95% were MCTC; a rare MC in skin and lymph nodes was MCT or MCC. In lung alveoli 91% of MCs were MCT, 8% were MCTC and 1% MCC. In bowel mucosa 58% of MCs were MCT, 35% were MCTC and 7% MCC, whereas in bowel submucosa 83% of MCs were MCTC and 17% MCC. Within esophageal epithelium 38% were MCT and 62% MCTC; whereas, in esophageal subepithelium all were MCTC. This study further documents site-dependent diversity among normal human MCs and recognizes a novel third immunophenotype rich in chymase and relatively deficient in tryptase, the MCC cell.

Avidin↗