Liquid Chromatography Tandem Mass Spectrometry Based Label-Free Quantification Method for Assessment of Allergen-Induced Anaphylactoid Reactions

Mast cells are essential in mediating inflammatory processes. When activated, mast cells can rapidly release characteristic granules and various mediators into the interstitium. Tryptase (TPS) and β-hexosaminidase (HEXB) are typical protease mediators stored in granules and released upon activation. They have been recognized as important biomarkers of anaphylaxis, and the released level is associated with the severity of allergic reactions. In this study, a sensitive, accurate, and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneously quantifying the two biomarkers was developed and validated in LAD2 cell culture supernatant, and P₁₄R was used as internal standard. Good linearity was observed in the range of 50-2500 ng/mL for TPS and 10-2000 ng/mL for HEXB both with R² > 0.99. The matrix effect and recovery were both within acceptable limits. We quantified TPS and HEXB released from Laboratory of Allergic Disease 2 (LAD2) mast cells treated with several potential allergens, and the results demonstrate that the method can be used to investigate TPS and HEXB levels in LAD2 mast cell model during allergy research. We anticipate our approach to be a robust and sensitive assessment method for more biomarkers with similar kinetics characteristics and to be a major tool of allergic drug assessment or antiallergic drug development in research.

Mast cell tryptase and carboxypeptidase A expression in body fluid and gastrointestinal tract associated with drug-related fatal anaphylaxis

AIM: To investigate the expression of mast cell tryptase and carboxypeptidase A in drug-related fatal anaphylaxis.

METHODS: The expression of mast cell tryptase and carboxypeptidase A in 15 autopsy cases of drug-related fatal anaphylaxis and 20 normal autopsy cases were detected. First, the expression of mast cell tryptase was determined in stomach, jejunum, lung, heart, and larynx by immunofluorescence. Different tissues were removed and fixed in paraformaldehyde solution, then paraffin sections were prepared for immunofluorescence. Using specific mast cell tryptase and carboxypeptidase A antibodies, the expression of tryptase and carboxypeptidase A in gastroenterology tract and other tissues were observed using fluorescent microscopy. The postmortem serum and pericardial fluid were collected from drug-related fatal anaphylaxis and normal autopsy cases. The level of mast cell tryptase and carboxypeptidase A in postmortem serum and pericardial fluid were measured using fluor enzyme linked immunosorbent assay (FEIA) and enzyme linked immunosorbent assay (ELISA) assay. The expression of mast cell tryptase and carboxypeptidase A was analyzed in drug-related fatal anaphylaxis cases and compared to normal autopsy cases.

RESULTS: The expression of carboxypeptidase A was less in the gastroenterology tract and other tissues from anaphylaxis-related death cadavers than normal controls. Immunofluorescence revealed that tryptase expression was significantly increased in multiple organs, especially the gastrointestinal tract, from anaphylaxis-related death cadavers compared to normal autopsy cases (46.67 ± 11.11 vs 4.88 ± 1.56 in stomach, 48.89 ± 11.02 vs 5.21 ± 1.34 in jejunum, 33.72 ± 5.76 vs 1.30 ± 1.02 in lung, 40.08 ± 7.56 vs 1.67 ± 1.03 in larynx, 7.11 ± 5.67 vs 1.10 ± 0.77 in heart, P < 0.05). Tryptase levels, as measured with FEIA, were significantly increased in both sera (43.50 ± 0.48 μg/L vs 5.40 ± 0.36 μg/L, P < 0.05) and pericardial fluid (28.64 ± 0.32 μg/L vs 4.60 ± 0.48 μg/L, P < 0.05) from the anaphylaxis group in comparison with the control group. As measured by ELISA, the concentration of carboxypeptidase A was also increased more than 2-fold in the anaphylaxis group compared to control (8.99 ± 3.91 ng/mL vs 3.25 ± 2.30 ng/mL in serum, 4.34 ± 2.41 ng/mL vs 1.43 ± 0.58 ng/mL in pericardial fluid, P < 0.05).

CONCLUSION: Detection of both mast cell tryptase and carboxypeptidase A could improve the forensic identification of drug-related fatal anaphylaxis.

Is there a role of interstitial cells of Cajal and mast cells and eosinophils in appendicitis in children?

BACKGROUND/AIM

The aim of this study was to compare the distribution of interstitial Cajal cells, eosinophils, and mast cells in normal and inflamed appendices, and to evaluate the correlation of presence of these cells with severity of inflammation in appendicitis.

MATERIALS AND METHODS

The appendicitis group (n = 30) was divided further into three groups according to the macroscopic description and the histological findings. Ten normal appendices served as controls. Tissue samples were processed for routine histological examination. Additionally, all sections were immunohistochemically stained with CD117 and mast cell tryptase antibodies.

RESULTS

When specimens were compared in terms of Cajal cells, the observed mean number for the appendicitis group was 4.9 and for the control group it was 8.3. In contrast, eosinophils and mast cells were significantly increased in the appendicitis group when compared with the control group.

CONCLUSION

We detected that eosinophils and mast cells are increased in appendicitis, and correlate with the degree of inflammation of the appendix. The density of interstitial Cajal cells was significantly lower in patients with severe appendix inflammation compared to controls. The histopathological differences observed in this study may help elucidate the pathophysiology of appendicitis.

[Tryptase of mast cells in immune organs of developing chicken embryos]

OBJECTIVE

To observe the form, distribution and emerging time of the mast cells (MCs) and tryptase positive cells (TPCs) in the immune organs of different days old chicken embryos.

METHODS

The thymus, bursa of Fabricius and spleen of chicken embryos at different development time were taken and fixed in Carnoy's solution. The alcian blue/safranine O (AB/SO) and streptavidin-biotin complex (SABC) immunohistochemistry were used to observe the MCs and TPCs.

RESULTS

MCs were first present in the thymus, bursa and spleen of day 13-14 embryos. The number of MCs increased along with the development days. On day 16, TPCs were first found in the immune organs. The form and distribution of TPCs were similar to MCs, but the emerging time of TPCs was later than that of MCs.

CONCLUSION

Tryptase appears in the MCs in the immune organs of day 16 or later chicken embryos, and it is mainly located in the MCs of the connective tissues.

Cellular immune environment in endometrial polyps

STUDY OBJECTIVE

To investigate the immune environment of endometrial polyps (EPs).

DESIGN

Prospective case-control study.

SETTING

Teaching hospital and university research laboratory.

PATIENT(S)

Reproductive-age women undergoing hysteroscopy dilation and curettage for benign indications. Samples were collected from women with (n = 23) and without (n = 40) EPs.

INTERVENTION(S)

Endometrial samples were immunohistochemically stained with antibodies against mast cells (MCs) and regulatory T cells (Tregs).

MAIN OUTCOME MEASURE(S)

Tryptase+, chymase+, and c-Kit+ MCs and Foxp3+ Tregs were quantified in EPs and polyp-adjacent, polyp-distant, and control endometrium.

RESULT(S)

Densities of all MC types were highly significantly increased in EPs compared with adjacent, distant, and control endometrium. Chymase+ and c-Kit+ MCs were increased in density in adjacent compared with control endometrium. c-Kit+ MCs were also increased in distant compared with control endometrium. Foxp3+ Treg density was increased in EPs compared with distant and control endometrium and decreased in distant compared with control endometrium.

CONCLUSION(S)

This study provides novel insights into localized disturbances in the cellular immune environment within EPs consistent with EPs being inflammatory lesions associated with MC overactivity. Tregs are likely to be recruited to EPs in an attempt to suppress the inflammatory process due to the greatly increased presence of MCs. These immunologic disturbances are likely to be involved in the causation of abnormal bleeding and infertility in premenopausal women with EPs, and their role in the pathophysiology requires further research.

IL-17C and its receptor IL-17RA/IL-17RE identify human oral epithelial cell as an inflammatory cell in recurrent aphthous ulcer

BACKGROUND

Recurrent aphthous ulcer (RAU) is an ulcerative disease of non-keratinized oral mucosa. Colon and bronchial epithelial cells produce interleukin-17C (IL-17C) upon stimulation of Toll-like receptor 2 (TLR2), TLR3 and TLR5, which are highly expressed in epithelial cells in RAU lesions. We therefore investigated the eventual presence and function of IL-17C in cultured human oral keratinocytes (HOK) and control biopsies compared to RAU lesions.

METHODS

Expression of IL-17A, IL-17C, IL-17RA and IL-17RE was analysed in cultured HOK cells using quantitative real-time polymerase chain reaction (qRT-PCR). HOK cells were stimulated with IL-17C and analysed for IL-8 and tumour necrosis factor-α (TNF-α) using qRT-PCR. Control mucosa (n = 5) was immunostained for IL-17A, IL-17C, IL-8, TNF-α and mast cell tryptase and compared with RAU lesions (n = 5) using the mean grey scale value.

RESULTS

IL-17C, but no IL-17A, mRNA was found in cultured HOK cells. Components of the heterodimeric IL-17RA/IL-17RE receptor for IL-17C were also highly expressed. Stimulation of HOK with IL-17C increased TNF-α mRNA (P = 0.03; IL-8 increase was not statistically significant). HOK in RAU lesions stained intensively for IL-17C compared to controls (P = 0.006). This was associated with increased epithelial immunostaining of TNF-α (P = 0.04) and IL-8 (P = 0.02). Most of the inflammatory cells which stained for IL-17A in control mucosa and RAU lesions were also mast cell tryptase positive.

CONCLUSION

IL-17C is highly expressed in epithelial cells in RAU lesions, where it seems to stimulate oral keratinocytes via IL-17RA/IL-17RE to produce pro-inflammatory cytokines. Human oral epithelial cells are probably important inflammatory cells in RAU.

Cellular expression profile for interstitial cells of cajal in bladder - a cell often misidentified as myocyte or myofibroblast

BACKGROUND

Interstitial cells of Cajal (ICC) have been identified in urinary bladder of several species, but their presence in mice remains uncertain. Meanwhile, dozens of reports indicate that dysregulation of connexin 43 plays an important role in bladder overactivity, but its localization has not been clearly defined, with reports of expression in either the smooth muscle or in myofibroblasts. We recently identified a population of ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2) positive cells that resemble ICC and are distinct from smooth muscle, fibroblasts, myofibroblasts and neurons. Thus we sought to define more clearly the molecular signature of ICC and in doing so resolve some of these uncertainties.

PRINCIPLE FINDINGS

Immunofluorescent localization revealed that NTPDase2-positive cells lie closely adjacent to smooth muscle but are separate from them. NTPDase2 positive cells exhibited co-localization with the widely accepted ICC marker - c-kit. They were further shown to co-localize with other ICC markers CD34 and Ano1, but not with mast cell marker tryptase. Significantly, they show convincing co-localization with connexin 43, which was not present in smooth muscle. The identity of these cells as ICC was further confirmed by the presence of three mesenchymal markers - vimentin, desmin, and PDGFβ receptor, which indicates their mesenchymal origin. Finally, we observed for the first time, the presence of merlin/neurofibromin 2 in ICC. Normally considered a neuronal protein, the presence of merlin suggests ICC in bladder may have a role in neurotransmission.

CONCLUSIONS

NTPDase2 positive cells in mice bladder are ICC, which can be defined by the presence of c-Kit, CD34, Ano1, NTPDase2, connexin 43, vimentin, desmin, PDGFβ receptor and merlin/NF2. These data establish a definitive molecular expression profile, which can be used to assist in explorations of their functional roles, and the presence of NTPDase2 suggests that purinergic signaling plays a role in regulation of ICC function.

Tryptase-positive mast cells and angiogenesis in keloids: a new possible post-surgical target for prevention

Literature data indicate that mast cells (MCs) are involved in angiogenesis through the release of several pro-angiogenetic factors among which tryptase, a serine protease stored in MC granules, is one of the most active. However, no data are available concerning the role of MCs during keloids' angiogenesis. In this study, we evaluated the correlations of the number of MCs positive to tryptase (MCDPT) and microvascular density (MVD) within a series of 15 keloids and 10 normotrophic scars, by means of immunohistochemistry and image analysis methods. Data demonstrated a significant difference of MVD and MCDPT between keloids and normotrophic scars and a significant correlation between MVD and MCDPT in keloids. Our results suggest that tryptase-positive MCs might play a key role in keloids' angiogenesis. In this context, several tryptase inhibitors might be clinically evaluated as a possible new anti-angiogenetic approach to prevent keloid formation after surgery.

Subcorneal pustular dermatosis an immnohisto-pathological perspective

Subcorneal pustular dermatosis (SPD) represents a chronic, relapsing sterile pustular eruption, involving the trunk and flexoral proximal extremities. A 54-year-old female presented with recurrent, flaccid pustules measuring several millimeters in diameter, on normal and mildly erythematous skin of the groin and submammary areas. Biopsies for hematoxylin and eosin (H&E) examination, direct immunofluorescence (DIF) and immunohistochemistry (IHC) analysis were performed. The H&E staining demonstrated typical features of SPD, including some damage within dermal pilosebaceous units subjacent to the subcorneal blistering process. DIF revealed strong deposits of immunoreactants IgG, IgM, fibrinogen and complement/C3, present in a shaggy pattern within the subcorneal disease areas; in focal, areas of the basement membrane junction and in focal pericytoplasmic areas of epidermal keratinocytes. IHC revealed strong positivity to HLA-DPDQDR, mast cell tryptase, CD68, and ZAP-70 in the subcorneal inflammatory infiltrate, and surrounding dermal blood vessels. Myeloperoxidase was also positive. Positive staining with the anti-ribosomal protein S6-pS240 at the edges of hair follicles and sebaceous glands subjacent to the subcorneal blisters was also noted.

CONCLUSIONS

We conclude that this disorder may have several components in its etiopathology, including a possible restricted immune response and a possible genetic component; these possibilities warrant further investigation.

[Allergic mediators in tear from children with seasonal and perennial allergic conjunctivitis]

PURPOSE

To evaluate the concentration of allergic mediators in tears of children with seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC) compared with controls.

METHODS

Twenty children with allergic conjunctivitis (17 SAC, and 3 PAC) and sixteen healthy children were included in this study. Tear samples were collected using a Merocel sponge (Oasis, 0525), and immediately eluted by incubation in elution buffer and subsequent centrifugation at 20,000 rpm for 30 min at 4°C. Concentrations of histamine (HIS), tryptase (TPS), eosinophil chemotactic factor (ECF), major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), IgE and E-selectin were measured using enzyme linked immunosorbent assays (ELISA). Data were compared with the Mann-Whitney U test (P<.05), and multivariate analyses were also performed.

RESULTS

Tear levels of TPS (P=.014), MBP (P=.032), ECP (P=.0041), IgE (P=.014) and EDN (P=.00077) showed significant differences in children with SAC and PAC compared to controls.

CONCLUSION

The simultaneous analyses of allergic mediators in the tears of children with SAC and PAC showed a significant elevated concentration in EDN, ECP and MBP in allergic group and decreased levels in IgE and TPS. Statistical analyses showed a diagnostic accuracy of 94.4% using the eight molecules panel.

Mast cell density and angiogenesis in oral dysplastic epithelium and low- and high-grade oral squamous cell carcinoma

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is one of the 10 most common malignant tumors and SCC accounts for approximately 94% of all oral malignancies. The risk of malignant transformation in dysplastic lesions is greater than that of normal oral mucosa. The definite roles of mast cells and angiogenesis in OSCC have been under debate. The aim of this study was to compare mast cell count (MCC) and microvessel density (MVD) among normal oral mucosa, oral dysplastic epithelium and low- and high- grade OSCC.

MATERIAL AND METHODS

A total of 42 specimens of OSCC (21 high- and 21 low-grade) were collected, along with six normal and 22 dysplastic oral mucosa. The mean MCC and MVD, as well as the correlation between them, were evaluated by immunohistochemical staining.

RESULTS

Statistically significant increases in mean MCC and MVD were observed between normal oral mucosa and epithelial dysplasia, normal oral mucosa and OSCC and epithelial dysplasia and OSCC (P < 0.05), but there were no statistically significant differences in MCC and MVD between low- and high-grade OSCC. Also, the Spearman's correlation coefficient showed a significant correlation between MCC and MVD (r = 0.727, P < 0.001).

CONCLUSIONS

The significant correlation found between MCC and MVD is in agreement with the idea that mast cells promote tumor progression via upregulation of angiogenesis. MCC and the degree of angiogenesis can potentially be used as indicators of the evolution of SCC from epithelial dysplasia.

Perioperative anaphylaxis

The incidence of immune-mediated anaphylaxis during anesthesia ranges from 1 in 10,000 to 1 in 20,000. Neuromuscular blocking agents are most frequently incriminated, followed by latex and antibiotics, although any drug or substance used may be a culprit. Diagnosis relies on tryptase measurements at the time of the reaction and skin tests, specific immunoglobulin E, or basophil activation assays. Treatment consists of rapid volume expansion and epinephrine administration titrated to symptom severity.

[The role of tryptase assay in recognition of anaphylactic reaction to muscle relaxants]

The incidence of allergic reactions during anaesthesia has been estimated to be from 1:3500 to 1:20000, with muscle relaxants being the most common allergens. Symptoms may involve all organs and systems with various intensities--from mild skin reactions to bronchospasm and cardiovascular collapse in the most severe cases. In a case of suspected perioperative allergic reaction, the management should not be limited to resuscitation and restoration of basic life functions, but must include careful investigation of potential allergens. An appropriate diagnostic strategy is essential for confirmation of an allergic reaction, identification of the allergen, and recommendations for future prevention. In this review, the various aspects of anaphylaxis and anaphylactoid reactions to muscle relaxants are discussed, including the role of tryptase and its assay in the diagnostic regimen.

Prognostic significance of mast cell number and microvascular density for the survival of patients with primary colorectal cancer

BACKGROUND AND AIM

The prognostic relevance of tumor-related angiogenesis and mast cell presence in colorectal cancer remains controversial. The aim of the current study was to assess the mast cell and microvessel densities (MCD and MVD) in the invasive front of colorectal cancers and to determine their prognostic relevance for survival of the patient with colorectal carcinoma.

METHODS

Histochemistry and immunohistochemistry were used to identify mast cells by toluidine blue (TB) histochemical staining and tryptase (Try) immunohistochemical staining and to determine the MVD in 106 biopsies from patients with 57 colonic and 49 rectal primary cancers. The MVD was assessed using CD31 as an endothelial cell marker.

RESULTS

Significant positive correlations were found between the MVD in the 'hot spots' and MCD-Try and MCD-TB (R = 0.623 and R = 0.414, respectively, P < 0.001). The survival analyses showed that the patients with hypovascular tumor tissues had significantly longer survival than those with hypervascular tumor biopsies (P < 0.0001). Analogous significant correlation was observed for MCD-Try: patients with low MCD-Try had significantly better prognosis compared to those with high MCD (P = 0.038). In the multivariate Cox's hazard analysis of the 'hot spots' MVD was found to be an independent prognostic factor (P = 0.0007), together with the presence of invasion of lymph vessels (P = 0.017) and the presence of regional lymph node metastases (P = 0.028).

CONCLUSION

We suggest that the assessment of MVD and tryptase-positive mast cells in the invasive front of the primary colorectal cancer could be a useful tool for prognosis of patients after surgical therapy.

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.

[The clinical significance of mast cell tryptase in bronchial alveolar lavage fluid in interstitial lung diseases]

Mast cell tryptase plays an important role in fibrosis. Tryptase levels in bronchial alveolar lavage fluid (BALF) from patients with interstitial lung diseases are frequently increased, but little is known of the clinical significance. The study population consisted of 93 patients [38 with sarcoidosis, 23 with collagen vascular disease (CVD), and 32 with idiopathic pulmonary fibrosis (IPF)]. BALF tryptase levels were measured with a newly developed B12 antibody-fluoroimmunocap method (UniCAP method), which can detect an activated form of tryptase. We examined the relationship between BALF tryptase levels and clinical parameters of the diseases. BALF tryptase was detected in 7 (18.4%) patients with sarcoidosis, 7 (30.4%) with CVD, and 14 (45.8%) with IPF. In tryptase-positive group, serum ACE levels and the numbers of BALF-mast cells and lymphocytes were higher than the tryptase-negative group in sarcoidosis, serum LDH levels were higher in CVD, and the number of BALF-lymphocyte and Hugh-Jones grade were higher in IPF. Furthermore, tryptase-positive IPF cases had a poorer outcome than the tryptase-negative group by Kaplan-Meier analysis. Tryptase in BALF detected with the UniCAP method may be associated with disease activity in sarcoidosis and CVD, and with severity and poor prognosis in IPF. BALF tryptase measurement may be useful in the assessment of disease activity and severity in various interstitial lung diseases.

Detection of phospho-STAT5 in mast cells: a reliable phenotypic marker of systemic mast cell disease that reflects constitutive tyrosine kinase activation

Systemic mastocytosis (SM) is characterized by the abnormal proliferation and accumulation of mast cells (MCs). Constitutive activation of kit, a receptor tyrosine kinase (TK), has been associated with all types of SM. Signal transducers and activators of transcription (STATs), such as STAT5, mediate downstream kit signalling. We hypothesized that nuclear phospho-STAT5 (pSTAT5) in MCs might reflect TK activation and would be a marker of abnormal MCs in SM. Expression of tryptase, CD25, CD2 and pSTAT5 was evaluated by immunohistochemistry (IHC) on archival cases of SM and cutaneous mastocytosis (CM). pSTAT5 was detected in 23/23 of SM and 1/9 of CM MC nuclei. 23/23 SM had CD25 + MCs. Control tissue MCs were negative for pSTAT5. Nuclear pSTAT5 in MCs from SM reflects abnormal TK activation. We propose nuclear pSTAT5 positivity in MCs as an additional minor phenotypic criterion for diagnosis of SM in future World Health Organization classification schemes.

Targeting adenosine receptors in the treatment of allergic rhinitis: a randomized, double-blind, placebo-controlled study

BACKGROUND

There is evidence that adenosine plays a role in the pathogenesis of asthma and rhinitis; however, it is currently unclear whether adenosine receptors are useful therapeutic targets in the treatment of allergic airway diseases.

OBJECTIVE

The study evaluated the efficacy of intranasal treatment with an adenosine A(2A) receptor agonist/adenosine A(3) receptor antagonist (50 micro g), administered twice daily for 7 days, to reduce nasal symptoms and release of inflammatory mediators following intranasal allergen challenge in patients with allergic rhinitis (AR). The compound was compared with twice-daily treatment with intranasal fluticasone proprionate nasal spray (FPANS) for 7 days.

METHODS

A randomized, double-blind, double-dummy, placebo-controlled, three-way balanced, incomplete block, crossover study was conducted on 48 males with verified AR. Following intranasal challenge with either an extract from the house dust mite (HDM), Dermatophagoides pteronyssinus, rye grass or cat dander, nasal responses and the concentrations of albumin, tryptase, myeloperoxidase, eosinophilic cationic protein, epithelial neutrophil-activating protein-78 (ENA-78), IL-5 and IL-8 in nasal secretions were measured and treatment groups were compared.

RESULTS

Drug improved nasal blockage but had no significant effect on rhinorrhoea, number of sneezes or peak nasal inspiratory flow measurements when compared with placebo. Drug reduced tryptase release after EAR but did not significantly reduce the levels of other mediators.

CONCLUSION

A novel agonist/antagonist of adenosine A(2A) and A(3) receptors appears to have limited clinical benefit in both the early-phase and the late-phase response to intranasal allergen challenge. However, reduction of some pro-inflammatory mediators suggests that comparable, more selective compounds may have additional benefits meriting further investigation.

Fibrosis in Hodgkin and non-Hodgkin lymphomas

There is little quantitative information about the amount of fibrosis in lymphomas. The aim of the present study was to investigate the amount of fibrosis in lymphomas and to highlight the relationship between fibrosis and mast cells, the key players of fibrosis. Tissue sections of 60 patients with diagnosis of lymphoma were reevaluated for classification. The mean fibrotic-stained area percentage (F-SAP) was determined in van Gieson-stained digital images using image analysis (Mediscope, Dokuz Eylul University, Clinical Engineering, Turkey). Mast cells were visualized using streptavidin peroxidase immunohistochemistry with anti-tryptase staining. Twenty-seven (44%) cases were Hodgkin's lymphoma (HL). F-SAP was 11.09+/-8.96 and 1.72+/-1.76 for HL and non-HL cases (Mann-Whitney U, p<0.000), and the mean mast cell count (MMCC) was 24.63+/-13.58 and 8.03+/-8.07, respectively (Mann-Whitney U test, p<0.000). There was a significant difference between F-SAP and MMCC concerning different types of lymphomas (Kruskal-Wallis test, p>0.000). F-SAP was highest in nodular sclerosis HL, and MMCC was highest in mixed cellular HL. There was a strong positive correlation between MMCC and F-SAP (Pearson Correlation test, p<0.000, r=0.51). These results suggest that the amount of fibrosis demonstrates differences in subtypes of lymphomas, and mast cells are increased in fibrosing lymphomas. However, it seems likely that more than one cell type is involved.

Mastocytosis: state of the art

Mastocytosis is a neoplastic disease involving mast cells (MC) and their CD34+ progenitors. Symptoms in mastocytosis are caused by biological mediators released from MC and/or the infiltration of neoplastic MC in various organs, the skin and the bone marrow being predominantly involved. A WHO consensus classification for mastocytosis exists, which is widely accepted and includes three major categories: (1) Cutaneous mastocytosis (CM), a benign disease in which MC infiltration is confined to the skin, is preferentially seen in young children and exhibits a marked tendency to regress spontaneously. (2) Systemic mastocytosis (SM) which is commonly diagnosed in adults and includes four major subtypes: (i) indolent SM (ISM, the most common form involving mainly skin and bone marrow); (ii) a unique subcategory termed SM with an associated non-mast cell clonal hematological disease (SM-AHNMD); (iii) aggressive SM usually presenting without skin lesions, and (iv) MC leukemia, probably representing the rarest variant of human leukemias. (3) The extremely rare localized extracutaneous MC neoplasms, either presenting as malignancy (MC sarcoma) or as benign tumor termed extracutaneous mastocytoma. Diagnostic criteria for mastocytosis are available and are widely accepted. SM criteria include one major criterion (multifocal compact tissue infiltration by MC) and four minor criteria: (1) prominent spindling of MC; (2) atypical immunophenotype of MC with coexpression of CD2 and/or CD25 (antigens which have not been found to be expressed on normal/reactive MC); (3) activating (somatic) point mutations of the c-kit proto-oncogene usually involving exon 17, with the imatinib-resistant type D816V being most frequent, and (4) persistently elevated serum tryptase level (>20 ng/ml). To establish the diagnosis of SM, at least one major and one minor criterion, or at least three minor criteria, have to be fulfilled. The natural clinical course of mastocytosis is variable. Most patients, in particular those with CM and ISM, remain in an indolent stage over many years or even decades, while others, in particular those with aggressive SM, SM-AHNMD, or mast cell leukemia, show a progressive course, usually with a fatal outcome.

Mast cell infiltration is a favourable prognostic factor in diffuse large B-cell lymphoma

Previous studies indicate that the inflammatory response in diffuse large B-cell lymphomas (DLBCL) is important for the clinical outcome. Mast cells are key regulators in this response; we investigated whether the number of tryptase-positive mast cells is correlated with clinical outcome. Patients with many mast cells had a significantly better event-free survival (EFS) compared to those with few mast cells (P < 0.03 in both germinal centre (GC) and non-GC DLBCL. This supports the idea that the infiltration of mast cells is a reflection of the host inflammatory response and is related to a favourable outcome.

Submucosal connective tissue-type mast cells contribute to the production of lysophosphatidic acid (LPA) in the gastrointestinal tract through the secretion of autotaxin (ATX)/lysophospholipase D (lysoPLD)

Lysophosphatidic acid (LPA) is involved in a broad spectrum of biological activities, including wound healing and cancer metastasis. Autotaxin (ATX), originally isolated from a melanoma supernatant as a tumor cell motility-stimulating factor, has been shown to be molecularly identical to lysophospholipase D (lysoPLD), which is the main enzyme in the production of LPA. Although ATX/lysoPLD is known to be widely expressed in normal human tissues, the exact distribution of ATX-producing cells has not been fully investigated. In this study, we evaluated ATX/lysoPLD expression by immunohistochemical staining using a rat anti-ATX mAb in the human gastrointestinal tract and found that submucosal mast cells (MC) highly expressed this enzyme. This was confirmed by immunofluorescent double staining using mAbs to tryptase and chymase. Then, we isolated MC from human gastric tissue by an immunomagnetic method using CD117-microbeads and showed that a subpopulation of CD203c-positive MC showed positive staining for intracellular ATX/lysoPLD on flowcytometry. This was confirmed by Western blotting of the isolated cells. Moreover, a significant level of ATX/lysoPLD release could be detected in the culture supernatants of human MC by Western blot analysis. Our data suggest that submucosal MC play significant roles in various aspects of pathophysiology in the gastrointestinal tract by locally providing bioactive LPA through the production of ATX/lysoPLD.

Airway mucosal inflammation in COPD is similar in smokers and ex-smokers: a pooled analysis

Bronchial biopsy specimens from chronic obstructive pulmonary disease (COPD) patients demonstrate increased numbers of CD8+ T-lymphocytes, macrophages and, in some studies, neutrophils and eosinophils. Smoking cessation affects the rate of forced expiratory volume in one second (FEV(1)) decline in COPD, but the effect on inflammation is uncertain. Bronchial biopsy inflammatory cell counts were compared in current and ex-smokers with COPD. A pooled analysis of subepithelial inflammatory cell count data from three bronchial biopsy studies that included COPD patients who were either current or ex-smokers was performed. Cell count data from 101 subjects, 65 current smokers and 36 ex-smokers, were analysed for the following cell types: CD4+ and CD8+ T-lymphocytes, CD68+ (monocytes/macrophages), neutrophil elastase+ (neutrophils), EG2+ (eosinophils), mast cell tryptase+ and cells mRNA-positive for tumour necrosis factor-alpha. Current smokers and ex-smokers were similar in terms of lung function, as measured by FEV(1) (% predicted), forced vital capacity (FVC) and FEV(1)/FVC. The results demonstrate that there were no significant differences between smokers and ex-smokers in the numbers of any of the inflammatory cell types or markers analysed. It is concluded that, in established chronic obstructive pulmonary disease, the bronchial mucosal inflammatory cell infiltrate is similar in ex-smokers and those that continue to smoke.

Mast cells and lymphocyte subsets in pulps from healthy and carious human teeth

OBJECTIVE

To evaluate the presence of cytolytic T lymphocytes (CD8+), memory T cells (CD45RO+), helper T lymphocytes (CD4+), and mast cells in pulps from healthy and carious human teeth.

STUDY DESIGN

The teeth were separated into groups: I = unerupted; II = partially erupted, without caries; III = erupted, without caries; IV = erupted with shallow dentine caries; and V = teeth with pulp polyps. The immunoperoxidase staining procedure was used to detect CD8, CD45RO, CD4, and tryptase (mast cell marker) antigens. The number of each cell type was obtained by counting the number of cells per mm2.

RESULTS

Mast cells were only present in pulp polyps. Pulps from carious teeth contained more CD4+ and CD8+ cells than from noncarious teeth. There was a significant decrease in the number of lymphocytes in pulp polyps in comparison to the other groups.

CONCLUSIONS

Mast cells probably do not contribute to the early vascular or specific immune responses in the initial dental pulp pathosis, although they may be involved in a chronic phase of pulp inflammation such as pulp polyps. On the other hand, CD4+ and CD8+ T cells participate mainly in initial phenomena of the immune response to incipient caries and seem not to substantially contribute to the response in pulp polyps.

[Role of mast cells in the development of renal interstitial fibrosis in children with Henoch-Schonlein purpura nephritis]

OBJECTIVE

To investigate the role of mast cells in the development of renal interstitial fibrosis in children with Henoch-Schonlein purpura nephritis (HSPN) and possible mechanisms.

METHODS

Paraffin-embedded renal biopsy tissue sections from 20 children with HSPN were examined for the levels of tryptase-beta and transforming growth factor-beta1 (TGF-beta1) by immunohistochemical staining. Mast cells were counted by toluidine blue staining. Masson staining was used to assess the level of renal interstitial fibrosis and renal histopathological scores. Normal renal tissue sections from 5 nephrectomized children for nephroma were used as control group.

RESULTS

The percentages of positive tryptase-beta cellsand mast cells and the TGF-beta1 expression in the HSPN group were significantly higher than those in the control group (P < 0.05). The percentages of positive tryptase-beta cells and mast cells and the TGF-beta1 expression in renal tissue were positively correlated with the glomeruli histopathological score (r =0.940, 0.920, 0.937, respectively; P < 0.05) and were also positively correlated with the histopathological score of renal interstitium (r=0.903, 0.859, 0.948, respectively; P < 0.05). The level of renal interstitial fibrosis was positively correlated with the percentages of positive tryptase-beta cells and mast cells and the expression of TGF-beta1 (r =0.790, 0.766, 0.858, respectively; P < 0.05). There was a positive correlation between the percentages of positive tryptase-beta cells and mast cells (r =0.941, P < 0.05), between the percentage of positive tryptase-beta cells and the TGF-beta1 expression (r =0.897, P < 0.05) and between the percentage of positive mast cells and the TGF-beta1 expression (r=0.942, P < 0.05).

CONCLUSIONS

Tubulointerstitial mast cell infiltration is associated with the development of renal interstitial fibrosis in children with HSPN. Mast cells together with TGF-beta1 and mast cell-derived tryptase-beta may be involved in the development of the renal interstitial fibrosis in HSPN.

Role for protease activity in visceral pain in irritable bowel syndrome

Mediators involved in the generation of symptoms in patients with irritable bowel syndrome (IBS) are poorly understood. Here we show that colonic biopsy samples from IBS patients release increased levels of proteolytic activity (arginine cleavage) compared to asymptomatic controls. This was dependent on the activation of NF-kappaB. In addition, increased proteolytic activity was measured in vivo, in colonic washes from IBS compared with control patients. Trypsin and tryptase expression and release were increased in colonic biopsies from IBS patients compared with control subjects. Biopsies from IBS patients (but not controls) released mediators that sensitized murine sensory neurons in culture. Sensitization was prevented by a serine protease inhibitor and was absent in neurons lacking functional protease-activated receptor-2 (PAR2). Supernatants from colonic biopsies of IBS patients, but not controls, also caused somatic and visceral hyperalgesia and allodynia in mice, when administered into the colon. These pronociceptive effects were inhibited by serine protease inhibitors and a PAR2 antagonist and were absent in PAR2-deficient mice. Our study establishes that proteases are released in IBS and that they can directly stimulate sensory neurons and generate hypersensitivity symptoms through the activation of PAR2.

Value of eosinophil cationic protein and tryptase levels in bronchoalveolar lavage fluid for predicting lung function impairment in anaesthetised, asthmatic children

Bronchial hyperactivity, a key feature of active asthma in children, is a risk factor for respiratory adverse events in the peri-operative period. The presence of activated eosinophils in the lungs and mast cell degranulation can contribute to bronchial hyperreactivity. Eosinophil cationic protein is released by activated eosinophils and tryptase reflects mast cell degranulation. This study focused on the relationship of respiratory mechanics, eosinophil cationic protein and tryptase levels in bronchoalveolar lavage fluid in asthmatic and healthy children under general anaesthesia. We measured eosinophil cationic protein and tryptase levels in bronchoalveolar lavage fluid from 21 asthmatic and 21 healthy children following induction of general anaesthesia. Respiratory system resistance and dynamic compliance were measured during mechanical ventilation. Eosinophil cationic protein was more common in bronchoalveolar lavage fluid from asthmatics (12/21) than from controls (4/21, p = 0.01) and was present at higher levels (p = 0.002). Tryptase was also more common in the asthmatics (8/21 vs 1/21, p = 0.01). Respiratory resistance was significantly higher in asthmatic children with detectable eosinophil cationic protein levels than in those with undetectable eosinophil cationic protein levels (p = 0.019). Furthermore, 50% of the asthmatics with detectable eosinophil cationic protein exhibited bronchospasm after sampling their bronchoalveolar lavage fluid. These findings suggested that high levels of eosinophil cationic protein in the bronchoalveolar lavage fluid are associated with irritable airways, presumably secondary to airway inflammation, and this might be a useful marker for respiratory adverse events in the peri-operative period.

Diarrhoea-predominant IBS patients show mast cell activation and hyperplasia in the jejunum

BACKGROUND

Increased numbers of mast cells and mast cell activation in distal gut segments are associated with symptom onset and severity in irritable bowel syndrome (IBS). Although upper gut symptoms are common, mast cells have not been thoroughly evaluated in proximal gut in IBS patients.

METHODS

Jejunal biopsies obtained by Watson's capsule, aspiration of intestinal fluid and one blood sample were obtained in 20 diarrhoea-predominant patients with IBS (D-IBS) and 14 healthy volunteers (H). Psychological stress (Holmes-Rahe Scale) and depression (Beck's Depression Inventory) were evaluated at baseline and food and respiratory allergy excluded. Biopsies were processed for H&E staining and microscopic inflammation assessed by counting intraepithelial lymphocytes. Mast cells in lamina propria were counted by immunohistochemistry with CD117 (c-kit). Tryptase concentration was measured in intestinal fluid and serum.

RESULTS

D-IBS patients showed higher psychological stress than healthy volunteers (D-IBS: 203 (SD 114) v H: 112 (SD 99); p = 0.019). Immunohistochemical staining of jejunal mucosa revealed mild increase in intraepithelial CD3+ cells in D-IBS patients (D-IBS: 15.3 (SD 5.5; 95% CI 12.7 to 17.9) v H: 10.3 (SD 3.9; 95% CI 8.0 to 12.5); p = 0.006). Moreover, D-IBS patients showed marked increase in mast cells numbers (D-IBS: 34 (SD 9.3); H: 15.3 (SD 4.4) mast cells/hpf; p<0.001) and higher tryptase concentration in jejunal fluid (D-IBS: 0.45 (SD 0.38); H: 0.09 (SD 0.10) microg/l; p = 0.005). Upper gut symptoms were not associated with gender, mast cell counts, jejunal tryptase or basal stress.

CONCLUSION

This jejunal mucosal inflammatory profile may help identify diarrhoea-predominant IBS, a stress-related disorder.

Detection of local mast-cell activity in patients with food hypersensitivity

BACKGROUND

Mast cells play a central role in many inflammatory diseases and assessment of their activation may be of use to provide objective confirmation of the outcome of food challenge in the diagnosis of food hypersensitivity. However, to date, assessment of mast-cell activation using serum markers has been unsuccessful.

OBJECTIVE

The aim of this study was to explore whether locally released tryptase could be detected in stool samples from patients with food hypersensitivity.

METHODS

Nine patients (median age, 55 years; range, 26 - 68 years) with food hypersensitivity confirmed by double-blind placebo-controlled food challenge were included in the study. Tryptase concentration was assessed in stool samples collected before and after an open food challenge at home and symptoms were recorded throughout the study. Tryptase concentration was also assessed in stool samples from 16 apparently healthy individuals (median age, 44 years; range, 27 - 72 years).

RESULTS

Measurement of fecal tryptase levels in 16 healthy control subjects revealed an upper limit of the normal range (mean + 2 SD of log transformed data) of 10 ng/g. Fecal tryptase levels exceeded 10 ng/g in 7 out of 9 patients in one or more samples obtained during the study. The tryptase levels varied between patients in response to the food challenge and the individual mean levels of tryptase correlated with the corresponding levels of the inflammatory marker eosinophil protein X (rho = 0.7500, P = .02).

CONCLUSION

Measurement of tryptase levels in stool samples is feasible using the method described here. Our results revealed elevated concentrations of fecal tryptase in patients with food hypersensitivity. However, several factors, including food exposure, may account for the increase in fecal tryptase and further studies are necessary to elucidate the role of mast cells in food hypersensitivity.

Nerve growth factor immunoreactivity of mast cells in acute involuted human thymus

The acute involution of the thymus is induced by either exogenous or endogenous factors, including some infections (infection type involution). The present study was focused on both detection and immunocytochemical analysis of NGF immunopositive mast cells in child thymus with acute infection-induced involution. Autopsy thymus specimens from children with infection diseases (Sepsis, Encephalomyelitis, Varicella) were examined at light and electron microscopic level and compared to normal infantile thymuses. We observed a redistribution of NGF immunopositive mast cells in infection-affected child thymus, which lobular architecture was collapsed. A positive correlation between the degree of the involutive changes, increased distribution and enhanced NGF immunoreactivity of mast cells was defined. The possible involvement of NGF immunopositive mast cells in the process of acute thymus involution is discussed.

A functional comparison of canine and murine bone marrow derived cultured mast cells

Disorders involving mast cells are extremely common in dogs, ranging from allergic diseases to neoplastic transformation resulting in malignant mast cell tumors. Relatively little is known regarding the basic biologic properties of normal canine mast cells, largely due to the difficulty in reliably purifying large numbers from canine skin. In vitro generated bone marrow derived cultured mast cells (BMCMCs) are routinely used in both human and murine studies as a ready source of material for in vitro and in vivo studies. We previously developed a technique to generate canine BMCMCs from bone marrow derived CD34+ cells and demonstrated that these cells exhibit the phenotypic properties characteristic of mast cells and release histamine in response to IgE cross-linking. The purpose of the following study was to characterize the functional properties of these canine BMCMCs and contrast these with the functional properties of murine BMCMCs. Our work demonstrates that both IL-4 and IL-10 promote canine BMCMC proliferation, possibly through upregulation of Kit expression, while TGFbeta inhibits proliferation. The canine BMCMCs produce a variety of cytokines and chemokines in response to IgE cross-linking and chemical stimulation including IL-3, IL-4, IL-13, GM-CSF, RANTES, and MIP1alpha. Interestingly, the canine BMCMCs released significantly larger amounts of MCP-1 and tryptase and significantly smaller amounts of IL-6 following chemical stimulation and IgE cross-linking when compared to murine BMCMCs. Lastly, the canine BMCMCs produced larger amounts of active MMP9 than their murine counterparts. In summary, canine BMCMCs exhibit unique functional properties that distinguish them from murine BMCMCs and provide insight into the contribution of these cells to mast cell disorders in the dog.

[Hydrodistention of the bladder in patients with interstitial cystitis--clinical efficacy and its association with immunohistochemical findings for bladder tissues]

We retrospectively analyzed the clinical relevance of hydrodistention under anesthesia for patients having urgency and/or lower abdominal pain who were clinically diagnosed as having interstitial cystitis (IC) from May 1996 to May 2005. Their symptoms were refractory to anticholinergic or antiinflammatory agents. Hydrodistention was performed under general or spinal anesthesia with direct vision by cystoscopy and irrigation fluid was instilled into the bladder at a pressure of 80 cmH2O. Cystoscopic findings revealed glomerulation in 26 patients (96%), cracking in 10 (37%) and Hunner's ulcer in 3. Twenty-four patients (89%) obtained improvement of the objective symptoms after treatment. However, symptoms soon deteriorated in 16 patients, and the average duration of efficacy was only 4.7 months (SD; +/-3.7). There were two episodes of complication in this treatment. Bladder rupture occurred during hydrodistention, but was successfully managed with simple percutaneous perivesical drainage. One patient with acute pyelonephritis was treated with an antimicrobial agent without any additional treatment. Although bladder specimens were examined by immunohistochemistry, tryptase and c-kit were not linked with the mast cell count, severity of symptoms or treatment efficacy. Hydrodistention of the bladder may be recommended as the first treatment choice for patients with IC because it provides relatively high efficacy. However, the short duration of the efficacy requires a second-line treatment option for better management of patients with IC.

Anti-tryptase treatment using nafamostat mesilate has a therapeutic effect on experimental colitis

OBJECTIVE

Mast cell tryptase has been proposed to be involved in the pathogenesis of human inflammatory bowel disease (IBD). Recently, it was reported that a low dose of nafamostat mesilate (NM), a serine protease inhibitor that is widely used to treat disseminated intravascular coagulation (DIC) and acute pancreatitis, can selectively inhibit human tryptase activity. The aim of this study was to investigate the anti-inflammatory effects of NM on experimental colitis in rats.

MATERIAL AND METHODS

Colitis was induced in male Wistar rats using an enema of trinitrobenzene sulfonic acid (TNBS) dissolved in 50% ethanol. NM or 5-aminosalicylic acid (5-ASA), foundation therapy for mild-to-moderate IBD, was administered via the anus once a day on each of the 6 days after administration of TNBS. Colonic inflammation was assessed 1 week after TNBS administration.

RESULTS

Intracolonic administration of TNBS resulted in the infiltration of numerous tryptase-positive cells in the colonic mucosa. The colonic mucosal injury induced by TNBS was significantly decreased by treatment with NM or 5-ASA. The increases in thiobarbituric acid-reactive substances (TBA-RS), myeloperoxidase (MPO) activity, tumor necrosis factor (TNF)-alpha and cytokine-induced neutrophil chemoattractants-1 (CINC-1) in the colonic mucosa were inhibited in the NM group and the 5-ASA group, without significant differences between them.

CONCLUSIONS

These results indicate that a low dose of NM can inhibit the colonic mucosal inflammation induced by TNBS in rats, which suggests that anti-tryptase therapy using low doses of NM has excellent potential to become a new therapeutic strategy for IBD.

[Tryptase activity in colon mucosal samples of children with inflammatory bowel disease]

INTRODUCTION

mast cells are dispersed in many tissues, especially in the digestive and respiratory system mucosal membranes. Tryptase is the most important proteinase released from mast cells after degranulation. It influences strongly the cells and tissues by activating the inflammatory process.

THE AIM OF THE STUDY

was to assess the activity of tryptase in colon mucosa samples in children with inflammatory bowel diseases (IBD) and in children with bleedings from lower part of gastrointestinal tract (GTB), without inflammation.

MATERIAL AND METHODS

a group of 30 children with IBD was analyzed in the study. IBD is formed by three disease entities: ulcerative colitis (UC) - 14 patients, Crohn's disease (CD) - 9 patients and non-specific colitis (NSC) - 7 patients. Moreover, a group of 18 children with bleeding from lower part of gastrointestinal tract was studied. The activity of tryptase in homogenates of colon mucosal samples was estimated fluoroimmunoenzymatically.

RESULTS

the results of our analysis showed no statistically important difference between the mean activity of tryptase in groups of children with IBD and GTB (31442 +/- 1304 vs 31868 +/- 775 ug/l). The study of tryptase activities in different disease entities of IBD group showed, that its value in ulcerative colitis group was 31382 +/- 1170 ug/l, in Crohn's disease group it was 31536 +/- 1120 ug/l; in non-specific colitis group the tryptase activity was 32277 +/- 498 ug/l. The analysis with Kruskal-Wallis Anova test revealed that the differences are statistically significant (p = 0.034). In post hoc test the outstanding value is the tryptase activity in children with NSC. Activity of tryptase in colon in much higher than its activity in plasma (normal range 1-19 ug/l).

CONCLUSIONS

the activity of tryptase in mucosal membrane samples is much higher than in blood. The extent of mast cells degranulation may be dependent on the form of IBD.

Ultrastructural and Immunohistochemical Characterization of Normal Mast Cells at Multiple Body Sites

This article reviews the ultrastructural and immunohistochemical features of normal human mast cells (MC) at multiple tissue sites. Current literature indicates that granules containing discrete scrolls (scroll-rich morphology) are frequent in MC from bowel mucosa and lung, locations where the majority of MC show only tryptase immunoreactivity (MC(T)). In contrast, most MC from skin, breast parenchyma, axillary lymph nodes, and bowel submucosa are characterized by scroll-poor morphology (that is, granules are rimmed by incomplete scrolls forming parallel lamellae and containing central, amorphous granular material or grating/lattice-like structures) and show both tryptase and chymase immunoreactivity (MC(TC)). MC having granules with both scroll-rich and scroll-poor features can occur in all tissue sites, and an occasional MC, especially in lung and bowel, may show only chymase immunoreactivity (MC(C)). Chymase immunoreactivity in MC also is closely associated with avidin binding and carboxypeptidase reactivity. We conclude that there is ultrastructural and immunophenotypic diversity among normal human MC, although certain forms predominate in specific tissue environments. In skin, breast tissue, axillary lymph nodes, and bowel submucosa MC tend to have scroll-poor granules and stain for avidin, chymase, tryptase, and carboxypeptidase, whereas, in lung and bowel mucosa MC granules tend to be scroll-rich and stain only for tryptase with currently available reagents.