New Aspects in Thrombosis Research: Possible Role of Mast Cells as Profibrinolytic and Antithrombotic Cells

Venous thromboembolism represents a significant cause of morbidity worldwide. The factors that underly thrombophilia are manifold. The concept of Virchow defines the well known triad of stasis, humoral factors, and pathologies of the vascular wall. In the current article, an additional factor, the “accumulation of repair cells” is discussed. This novel concept highlights the mast cell that accumulates around thrombosed vessels and provides a number of important repair molecules including heparin, profibrinolytic tPA, and fibrinogenolytic β-tryptase. Thus, mast cell recruitment and activation may result in local thrombolysis and prevention of coagulation. In line with this concept, mast cell-deficient mice are more susceptible to lethal thrombogenic stimuli compared to normal mice. The factors (cytokines) that trigger mast cell accumulation and release of repair molecules have also been identified – the most important one appears to be stem cell factor (SCF). All in all, our novel concept suggests that the patho-physiology of thrombosis may involve a “physiologic” cell that provides the same repair molecules that are used for treatment of thrombotic disorders by the physician. Whether an altered availability of components of this cellular repair system can predispose for thrombophilia remains to be determined.

Spinal leptomeningeal metastases from prostate cancer

OBJECTIVE

Prostate cancer is a well known cause of spinal column metastases; however, an intradural location is extremely rare. It is considered to be a type of leptomeningeal spread. Cerebral seeding has usually occurred by the time of presentation. Due to a poor prognosis, surgery is rarely indicated, and controversially discussed.

PATIENT AND RESULTS

We review the known cases of spinal leptomeningeal prostate cancer spread, including our patient, who developed paraparesis over 6 weeks, 3 years after prostate cancer was diagnosed. Following surgical decompression and resection, the patient additionally received radiation therapy of the spinal meninges and antihormonal treatment. 6 months after surgery, the patient is still ambulatory with a good quality of life.

CONCLUSION

Spinal leptomeningeal metastases occur at a late stage of systemic disease, and the prognosis is generally poor. In the literature, outcomes after surgery are reported as devastating, with mortality and morbidity rates of up to 20% and 60%. The aim of surgery is to relieve pain, preserve or even restore neurological function, and reveal histology if uncertain. This may be achieved by debulking the tumor without placing the patient at an unacceptably high risk. Surgery should be performed in selected cases of spinal leptomeningeal metastases, in patients who are still ambulatory with controlled systemic disease, and should be followed by adjuvant therapy.

Spinal Leptomeningeal Metastases from Prostate Cancer

OBJECTIVE

Prostate cancer is a well known cause of spinal column metastases; however, an intradural location is extremely rare. It is considered to be a type of leptomeningeal spread. Cerebral seeding has usually occurred by the time of presentation. Due to a poor prognosis, surgery is rarely indicated, and controversially discussed.

PATIENT AND RESULTS

We review the known cases of spinal leptomeningeal prostate cancer spread, including our patient, who developed paraparesis over 6 weeks, 3 years after prostate cancer was diagnosed. Following surgical decompression and resection, the patient additionally received radiation therapy of the spinal meninges and antihormonal treatment. Six months after surgery, the patient is still ambulatory with a good quality of life.

CONCLUSION

Spinal leptomeningeal metastases occur at a late stage of systemic disease, and the prognosis is generally poor. In literature, outcomes after surgery are reported as devastating, with mortality and morbidity rates of up to 20 and 60%. The aim of surgery is to relieve pain, preserve or even restore neurological function, and reveal histology if uncertain. This may be achieved by debulking the tumor without placing the patient at an unacceptably high risk. Surgery should be performed in selected cases of spinal leptomeningeal metastases, in patients who are still ambulatory with controlled systemic disease, and should be followed by adjuvant therapy.

Major bleeding complications after cardiopulmonary resuscitation: impact of thrombolytic treatment

OBJECTIVE

The risk of bleeding complications caused by thrombolysis in patients with cardiac arrest and prolonged cardiopulmonary resuscitation is unclear. We evaluate the complication rate of systemic thrombolysis in patients with out-of-hospital cardiac arrest caused by acute myocardial infarction, especially in relation to duration of cardiopulmonary resuscitation.

DESIGN

The study was designed as retrospective cohort study, the risk factor being systemic thrombolysis and the end-point major haemorrhage, defined as life-threatening and/or need for transfusion. Over 10.5 years, emergency cardiac care data, therapy, major haemorrhage and outcome of 265 patients with acute myocardial infarction admitted to an emergency department after successful cardiopulmonary resuscitation were registered.

RESULTS

We observed major haemorrhage in 13 of 132 patients who received thrombolysis (10%, 95% confidence interval 5-15%), five of these survived to discharge, none died because of this complication. Major haemorrhage occurred in seven of 133 patients in whom no thrombolytic treatment had been given (5%, 95% confidence interval 1-9%), two of these survived to discharge. Taking into account baseline imbalances between the groups, the risk of bleeding was slightly increased if thrombolytics were used (odds ratio 2.5, 95% confidence interval 0.9-7.4) but this was not significant (P = 0.09). There was no clear association between duration of resuscitation and bleeding complications (z for trend = 1.52, P = 0.12). Survival was not significantly better in patients receiving thrombolysis (odds ratio 1.6, 0.9-3.0, P = 0.12).

CONCLUSIONS

Bleeding complications after cardiopulmonary resuscitation are frequent, particularly in patients with thrombolytic treatment, but do not appear to be related to the duration of resuscitation. In the light of possible benefits on outcome, thrombolytic treatment should not be withheld in carefully selected patients.

New aspects in thrombosis research: possible role of mast cells as profibrinolytic and antithrombotic cells

Venous thromboembolism represents a significant cause of morbidity worldwide. The factors that underly thrombophilia are manifold. The concept of Virchow defines the well known triad of stasis, humoral factors, and pathologies of the vascular wall. In the current article, an additional factor, the "accumulation of repair cells" is discussed. This novel concept highlights the mast cell that accumulates around thrombosed vessels and provides a number of important repair molecules including heparin, profibrinolytic tPA, and fibrinogenolytic beta-tryptase. Thus, mast cell recruitment and activation may result in local thrombolysis and prevention of coagulation. In line with this concept, mast cell-deficient mice are more susceptible to lethal thrombogenic stimuli compared to normal mice. The factors (cytokines) that trigger mast cell accumulation and release of repair molecules have also been identified - the most important one appears to be stem cell factor (SCF). All in all. our novel concept suggests that the patho-physiology of thrombosis may involve a "physiologic" cell that provides the same repair molecules that are used for treatment of thrombotic disorders by the physician. Whether an altered availability of components of this cellular repair system can predispose for thrombophilia remains to be determined.

[Drugs for young Mozart. Medical treatment of Wolfgang as a child by his father Leopold Mozart]

Leopold Mozart (1719-1787), father of Wolfgang Amadé, had profound medical knowledge and was a passionate medical dilettante. As long as the young Mozart lived with his father and travelled on his concert tours with him, Leopold cared for his son in medical matters. Doctors were only consulted occasionally. In the extensive correspondence of Mozart's father drugs and treatments used for Wolfgang Amadé are reported in detail. This represents a reliable description of the pharmacological therapies of the late 18th century. The mentioned drugs are, as far as possible, viewed from todays medical perspective.

Spontaneous subarachnoid haemorrhage as a cause of out-of-hospital cardiac arrest

OBJECTIVE

Spontaneous subarachnoid haemorrhage as a cause of out-of-hospital cardiac arrest is poorly evaluated. We analyse disease-specific and emergency care data in order to improve the recognition of subarachnoid haemorrhage as a cause of cardiac arrest.

DESIGN

We searched a registry of cardiac arrest patients admitted after primarily successful resuscitation to an emergency department retrospectively and analysed the records of subarachnoid haemorrhage patients for predictive features.

RESULTS

Over 8.5 years, spontaneous subarachnoidal haemorrhage was identified as the immediate cause in 27 (4%) of 765 out-of-hospital cardiac arrests. Of these 27 patients, 24 (89%) presented with at least three or more of the following common features: female gender (63%), age under 40 years (44%), lack of co-morbidity (70%), headache prior to cardiac arrest (39%), asystole or pulseless electric activity as the initial cardiac rhythm (93%), and no recovery of brain stem reflexes (89%). In six patients (22%), an intraventricular drain was placed, one of them (4%) survived to hospital discharge with a favourable outcome.

CONCLUSIONS

Subarachnoid haemorrhage complicated by cardiac arrest is almost always fatal even when a spontaneous circulation can be restored initially. This is due to the severity of brain damage. Subarachnoid haemorrhage may present in young patients without any previous medical history with cardiac arrest masking the diagnosis initially.

A molecular model of type I allergy: identification and characterization of a nonanaphylactic anti-human IgE antibody fragment that blocks the IgE-FcepsilonRI interaction and reacts with receptor-bound IgE

BACKGROUND

The IgE-mediated activation of effector cells and antigen-presenting cells through the high-affinity receptor for IgE (FcepsilonRI) represents a key pathomechanism in type I allergy and many forms of asthma.

OBJECTIVE

We sought to establish an in vitro molecular model for the interaction of human FcepsilonRI, IgE, and the corresponding allergen and to identify monoclonal anti-human IgE antibodies with a therapeutic profile different from previously established anti-IgE antibodies.

METHODS

Human FcepsilonRI alpha chain, a human monoclonal allergen-specific IgE antibody (chimeric Bip 1), and the corresponding allergen, the major birch pollen allergen Bet v 1, were produced as recombinant proteins and analyzed by means of circular dichroism and native overlays, respectively. Using this molecular model, as well as negative stain immunoelectron microscopic analysis, and in vitro cultivated human basophils, we characterized mouse anti-human IgE antibodies.

RESULTS

We established a molecular model for the interaction of human IgE with FcepsilonRI. Using this molecular model, we identified a nonanaphylactic anti-human IgE antibody fragment (Fab12), which blocked the IgE-FcepsilonRI interaction and reacted with effector cell-bound IgE.

CONCLUSION

Fab12 represents a candidate molecule for therapy of atopy and asthma because it can be used for the depletion of circulating IgE antibodies, as well as for the depletion of IgE-bearing cells.

Characterization of human prostate mast cells and their increase in periprostatic vein thrombosis

Recent data suggest that mast cells (MCs) and their products are involved in the pathophysiology of thrombosis. In the present study, we analyzed the number, distribution, and phenotype of prostate MCs and periprostatic MCs in patients with unilateral periprostatic vein thrombosis (PVT) by immunohistochemical analysis and electron microscopy. MCs reacted with monoclonal antibodies to tryptase, chymase, and c-kit/CD117 and stained positively for tissue-type plasminogen activator (tPA) and urokinase receptor (uPAR/CD87) but did not express detectable urokinase (uPA) or plasminogen activator inhibitors (PAI-1, PAI-2). We found an increase in the mean +/- SEM number of MCs in PVT compared with control (PVT, 14.36 +/- 1.57 vs control, 5.23 +/- 0.57/mm2). The majority of MCs accumulated in the adventitia of thrombosed veins and showed a decrease in chymase expression. As MCs increase in number in PVT and express a profibrinolytic phenotype, we hypothesize that MC-derived molecules have a role in endogenous fibrinolysis.

[Dysplastic bronchial changes as etiology of sudden death. A plea for the necessity of diagnostic autopsy]

BACKGROUND AND OBJECTIVE

Legal regulations of cadaver examination and autopsy require fundamental changes. Regulations that result in up to 75% errors in the recorded cause of death on the death certificate make no sense. As an example, rare disease of bronchial malformation may cause sudden, unexpected death but is only detectable at autopsy with subsequent histological examination.

PATIENTS AND METHODS

In an series of 17.204 autopsies (from 1980 to 1999) 894 cases of sudden, unexpected death were examined. In 28 cases (3.1%) only histological examination of the lungs provided the cause of natural death.

RESULTS

Bronchial dysplasia may be clinically silent and leads to focal panazinar emphysema and atelectasis due to chronic airflow obstruction and an "air trapping" mechanism. Subsequent pulmonary hypertension results in a cor pulmonale, which may fail suddenly and unexpectedly.

CONCLUSION

The diagnostic problems of natural death justifies the performance of an autopsy. This fact should be recognized legally. Using the example of bronchial malformation, it is shown that only an autopsy may reveal the exact cause of death.

Pulmonary embolism as a cause of cardiac arrest: presentation and outcome

BACKGROUND

Pulmonary embolism (PE) is a possible noncardiac cause of cardiac arrest. Mortality is very high, and often diagnosis is established only by autopsy.

METHODS

In a retrospective study, we analyzed clinical presentation, diagnosis, therapy, and outcome of patients with cardiac arrest after PE admitted to the emergency department of an urban tertiary care hospital.

RESULTS

Within 8 years, PE was found as the cause in 60 (4.8%) of 1246 cardiac arrest victims. The initial rhythm diagnosis was pulseless electrical activity in 38 (63%), asystole in 19 (32%), and ventricular fibrillation in 3 (5%) of the patients. Pronounced metabolic acidosis (median pH, 6.95, and lactate level, 16 mmol/L) was found in most patients. In 18 patients (30%), the diagnosis of PE was established only postmortem. In 42 (70%) it was diagnosed clinically, in 24 of them the diagnosis of PE was confirmed by echocardiography. In 21 patients, 100 mg of recombinant tissue-type plasminogen activator was administered as thrombolytic treatment, and 2 (10%) of these patients survived to hospital discharge. Comparison of patients of the thrombolysis group (n = 21) with those of the nonthrombolysis group (n = 21) showed a significantly higher rate of return of spontaneous circulation (81% vs 43%) in the thrombolysis group (P=.03).

CONCLUSIONS

Mortality related to cardiac arrest caused by PE is high. Echocardiography is supportive in determining PE as the cause of cardiac arrest. In view of the poor prognosis, thrombolysis should be attempted to achieve return of spontaneous circulation and probably better outcome.

[Dr. Nicolaas Tulp. A critical view of Rembrandt's Anatomy Lesson]

Rembrandt's painting 'The Anatomy Lesson' (1632) is revolutionary in its portrayal of members of the Anatomic Guild. It has an entirely new composition and vividly depicts the dynamics of the event and the interest of the participants. However, the structures of the dissected forearm have been taken from a copy and not from the original. The possibility of anatomic errors is discussed here. A short biography of Dr. Tulp is also included.

Mast cells are augmented in deep vein thrombosis and express a profibrinolytic phenotype

A number of recent data suggest that mast cells (MC) and their products are involved in the pathophysiology of thrombosis. In the current study, we have evaluated the number, distribution, and phenotype of MC in patients with deep vein thrombosis of the lower limb (DVT) (n = 15). Contralateral nonthrombosed limb veins served as control (CO). MC were examined by Giemsa staining and by immunohistochemistry using antibodies against tryptase, chymase, tissue-type plasminogen activator (tPA), urokinase (uPA), urokinase receptor (uPAR), and plasminogen activator inhibitors (PAI-1, PAI-2). We found an increase in the number of tryptase-positive MC in DVT compared with CO (DVT: 9.1+/-1.0 v CO: 4.7+/-0.6 MC/mm2, P < .05). Most of these MC appeared to accumulate in the adventitia of the thrombosed veins, in vicinity of the vasa vasorum. In both DVT and CO, MC reacted with monoclonal antibodies to c-kit, tryptase, and chymase. MC also stained positive for tPA and urokinase receptor, but did not express detectable PAI-1 or PAI-2. As compared with CO, a decreased proportion of MC in DVT was found to stain positive for chymase and tPA. Together, our results show that MC increase in number in DVT and express a profibrinolytic phenotype. We hypothesize that MC and MC-derived profibrinolytic molecules play a role in the pathophysiology of DVT.

The mast cell as site of tissue-type plasminogen activator expression and fibrinolysis

Recent data suggest that mast cells (MC) and their products (heparin, proteases) are involved in the regulation of coagulation and fibrino(geno)lysis. The key enzyme of fibrinolysis, plasmin, derives from its inactive progenitor, plasminogen, through catalytic action of plasminogen activators (PAs). In most cell systems, however, PAs are neutralized by plasminogen activator inhibitors (PAIs). We report that human tissue MC as well as the MC line HMC-1 constitutively produce, express, and release tissue-type plasminogen activator (tPA) without producing inhibitory PAIs. As assessed by Northern blotting, highly enriched lung MC (>98% pure) as well as HMC-1 expressed tPA mRNA, but did not express mRNA for PAI-1, PAI-2, or PAI-3. The tPA protein was detectable in MC-conditioned medium by Western blotting and immunoassay, and the MC agonist stem cell factor (c-Kit ligand) was found to promote the release of tPA from MC. In addition, MC-conditioned medium induced fibrin-independent plasmin generation as well as clot lysis in vitro. These observations raise the possibility that MC play an important role in endogenous fibrinolysis.

Expression of stem cell factor (SCF) and SCF receptor (c-kit) in synovial membrane in arthritis: correlation with synovial mast cell hyperplasia and inflammation

OBJECTIVE

Stem cell factor (SCF), the ligand for the SCF receptor (c-kit) expressed on precursors and mature mast cells (MC), is a major agonist for human MC (e.g., SCF induces MC development, chemotaxis, activation, proliferation of MC precursors, mediates MC adhesion, and changes MC releasability). We investigated expression of SCF and c-kit in synovial membrane with particular reference to the mechanism of local MC hyperplasia and inflammation in arthritis.

METHODS

We conducted single and double labeling immunohistochemistry (ABC, APAAP, indirect immunofluorescence techniques) with antibodies to SCF, c-kit, MC tryptase, Ki-67 antigen (marker for proliferating cells), and CD68 (monocyte/macrophage marker). Synovial specimens analyzed were from 31 patients: traumatic arthritis (TrA, n=9), osteoarthritis (OA, n=12), and rheumatoid arthritis (RA, n=10). Control experiments were performed on human lung, skin, and buccal mucosa tissues, on the HMC-1 mast cell line, and isolated lung MC. Morphometry was performed by computerized image analysis.

RESULTS

Synovial c-kit expression was found to be restricted to MC, whereas SCF is detected in synovial lining cells, stromal fibroblasts, monocyte/macrophages, endothelial cells, and in vascular basement membranes. SCF staining was localized to MC as well, but it was not possible to specify whether this represents SCF produced by or bound (via c-kit) to MC. In inflamed synovial membranes/areas, SCF was found to be redistributed into the extracellular matrix. Redistribution of SCF was accompanied by degranulation and/or accumulation of c-kit+ MC, the hyperplasia of which correlated positively with histologic inflammation/inflammatory cell densities, but did not appear to involve MC proliferation in situ. These findings appeared to be common for all the conditions (TrA, OA, RA) studied.

CONCLUSION

In addition to the demonstration/characterization of SCF and c-kit protein expression in human synovium, results of this study suggest the hypothesis that, in arthritis, local mobilization of SCF may play a role in the development of synovial MC hyperplasia without inducing in situ proliferation of MC, and that the synovial SCF/MC c-kit system may contribute to the local nonspecific inflammatory response/arthritic flares in TrA, OA, and RA.

Accuracy and impact of presumed cause in patients with cardiac arrest

BACKGROUND

International guidelines recommend differentiation between cardiac and noncardiac causes of cardiac arrest. The aim of this study was to find the rate of agreement between primarily postulated and definitive causes of cardiac arrest.

METHODS AND RESULTS

We retrospectively analyzed the primarily presumed cause of cardiac arrest as determined by the emergency room physician on admission in all patients admitted to the emergency department of one urban tertiary care hospital. This was compared with the definitive cause as established by clinical evidence or autopsy. Within 4 years, the initially presumed cause was unclear in 24 (4%) of 593 patients. In the remaining 569 patients, the presumed cause was correct in 509 (89%) and wrong in 60 (11%) cases. Cardiac origin was presumed in 421 (71%) and the definitive cause in 408 (69%) cases. Noncardiac origin was presumed in 148 (25%) and the definitive cause in 185 (31%) patients. Presumed cardiac cause was sensitive (96%) but less specific (77%). Noncardiac causes such as pulmonary embolism, cerebral disorders, or exsanguination were those most frequently overlooked. Asystole occurred significantly more often in patients in whom presumed cause remained undetermined or differed from the definitive cause.

CONCLUSIONS

Cause of cardiac arrest is not as easily recognized as anticipated, especially when the initial rhythm is different from ventricular fibrillation. This might affect comparability of study results, therapeutic strategies, prognosis, and outcome. Patients in whom the presumed cause was confirmed as being correct had significantly better survival and neurological outcome.

Bile duct adenocarcinoma mimicking veno-occlusive disease after autologous bone marrow transplantation for acute leukaemia

A 52-year-old female underwent autologous BMT because of acute myeloid leukaemia FAB M4 in second remission. Since the patient had no HLA-identical sibling she received a purged autologous BM transplant. On day +5 she developed signs of a sepsis syndrome with fluid retention and was treated with broad-spectrum antibiotic therapy. However, her body weight remained high, ascites and an increase of total serum bilirubin and alkaline phosphatase developed. The icterus worsened to a total bilirubin level of 25 mg/100 ml. Sonographic and endoscopic imaging showed a dilated gall bladder but disclosed a post-hepatic cause for the icterus. A transjugular liver biopsy on day +71 revealed severe cholestasis and siderosis. The patient remained aplastic with constantly increased bilirubin levels. On day +73 septic shock syndrome occurred and the patient died of multiorgan failure 3 days later. At autopsy, a highly differentiated bile duct adenocarcinoma at the porta hepatis, so-called Klatskin tumour, was found, explaining the fatal course with intractable cholestasis.

Phenotypic and functional characterization of mast cells derived from renal tumor tissues

Mast cells (MCs) originate from multipotent hematopoietic progenitor cells. However, MCs in various organs are heterogenous in terms of mediator or receptor expression and response to diverse stimuli. We characterized the phenotype and functional properties of human renal mast cells (HRMCs). Tissue was obtained from 17 patients suffering from renal tumors (transitional cell carcinoma, n = 4; renal cell carcinoma, n = 13). HRMCs were isolated by collagenase digestion. Double staining with toluidine blue and immunofluorescence using monoclonal antibodies (mAbs) revealed expression of stem cell factor (SCF)-receptor (c-kit/CD117), CD9, CD29, CD33, CD43, CD44, CD54, and CD63 on HRMCs. In contrast, HRMCs were not recognized by mAbs to CD2, CD3, CD4, CD11b, CD14, CD15, CD16, CDw17, CD19, or CD23. HRMCs were also negative for CD116 (granulocyte-macrophage colony-stimulating factor [GM-CSF] receptor alpha), CD123 (interleukin [IL]-3Ralpha), CD121a (IL-1R type I), CD122 (IL-2Rbeta), and CD127 (IL-7R) and were also found to lack C5aR (CD88). Ligand-induced activation of HRMCs through immunoglobulin (Ig)E-R or SCF-R (c-kit) resulted in histamine secretion (control: <10%; alphaIgE, 1 microg/mL: 50.12 +/-5.18%; rhSCF, 100 ng/mL: 29.24 +/- 22.39), whereas recombinant C5a, erythropoietin (EPO), IL-1 through 10, and GM-CSF exerted no effects. As determined by in situ staining, HRMCs contained tryptase, but only low or undetectable amounts of chymase. Electron microscopy confirmed the presence of MCs in renal tissues and revealed a scroll-rich granule population in HRMCs. Together, HRMCs are tryptase+, C5aR- mast cells exhibiting phenotypic and functional properties similar to those of lung MCs.

What have mast cells to do with edema formation, the consecutive repair and fibrinolysis?

Mast cells (MC) have been implicated in the activation of vascular endothelial cells, capillary leak formation, transmigration of white blood cells, and translocation of fibrinogen (and other plasma molecules) into the tissues, with consecutive edema formation. However, the mechanisms of repair that lead to tissue reconstitution after MC activation and edema formation have not been defined so far. In the present article, the possible contribution of MC to repair, in particular fibrinolysis, is discussed. Thus, accumulating evidence exists that human MC express and release the tissue-type plasminogen activator (tPA) in a constitutive manner. MC also express the urokinase receptor (uPAR) and heparin. Most importantly, however, MC lack plasminogen activator inhibitors (PAI-1, PAI-2, PAI-3). In line with this 'pro-fibrinolytic' profile of antigens, MC supernatants induce plasminogen-to-plasmin conversion and fibrin clot lysis in vitro. The c-kit ligand SCF upregulates uPAR expression, and the release of tPA from MC. These observations point to an important role of MC in endogenous fibrinolysis, a hitherto unrecognized (repair) function of this cell.

The c-kit ligand stem cell factor and anti-IgE promote expression of monocyte chemoattractant protein-1 in human lung mast cells

Recent data suggest that mast cells (MC) are involved in the regulation of leukocyte accumulation in inflammatory reactions. In this study, expression of leukocyte-chemotactic peptides (chemokines) in purified human lung MC (n = 16) and a human mast cell line, HMC-1, was analyzed. Northern blotting and reverse transcriptase-polymerase chain reaction (RT-PCR) showed baseline expression of monocyte chemoattractant protein (MCP)-1 mRNA in unstimulated MC. Exposure of MC to recombinant stem cell factor (rhSCF, 100 ng/mL) or anti-IgE (10 microgram/mL) was followed by a substantial increase in expression of MCP-1 mRNA. Neither unstimulated nor stem cell factor (SCF )-stimulated lung MC expressed transcripts for interleukin-8 (IL-8), macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, or RANTES by Northern blotting. The mast cell line HMC-1, which contains a mutated and intrinsically activated SCF-receptor, was found to express high levels of MCP-1 mRNA in a constitutive manner. Exposure of HMC-1 cells to rhSCF resulted in upregulation of MCP-1 mRNA expression, and de novo expression of MIP-1beta mRNA. The SCF-induced upregulation of MCP-1 mRNA in lung MC and HMC-1 was accompanied by an increase in immunologically detectable MCP-1 in cell supernatants (sup) (lung MC [<98%], control medium, 1 hour: 159 +/- 27 v SCF, 100 ng/mL, 1 hour: 398 +/- 46 pg/mL/10(6) cells; HMC-1: control, 1 hour: 894 +/- 116 v SCF, 1 hour: 1,536 +/- 265 pg/mL/10(6)). IgE-dependent activation was also followed by MCP-1 release from MC. MC-sup and HMC-1-sup induced chemotaxis in blood monocytes (Mo) (control: 100% +/- 12% v 2-hour-MC-sup: 463% +/- 38% v HMC-1-sup: 532% +/- 12%), and a monoclonal antibody (MoAb) to MCP-1 (but not MoAb to IL-8) inhibited Mo-chemotaxis induced by MC-sup or HMC-1-sup (39% to 55% inhibition, P < .05). In summary, our study identifies MCP-1 as the predominant CC-chemokine produced and released in human lung MC. MCP-1 may be a crucial mediator in inflammatory reactions associated with MC activation and accumulation of MCP-1-responsive leukocytes.

Expression of fibrinolytic antigens in redistributed cardiac mast cells in auricular thrombosis

Recent data suggest that auricular thrombosis is associated with an increase and accumulation of mast cells (MC) in the subendothelial region of the upper endocardium. However, the molecular basis and the functional role of MC in this process are not known. In the current study, expression of fibrinolytic and antifibrinolytic antigens in human cardiac MC was analyzed by immunohistochemistry. MC were found to react with antibodies against tissue-type plasminogen activator (tPA) and urokinase receptor (uPAR/CD87), but not with antibodies against urokinase (uPA) or plasminogen activator inhibitors (PAI-1, PAI-2). Significant changes were observed when the phenotype of accumulated MC in the upper endocardium in patients with auricular thrombosis was compared with the phenotype of myocardial MC in the same patients or with MC in normal hearts. These redistributed MC stained less intensely with antibodies against tPA and chymase but retained their staining for tryptase and uPAR. Together, these data indicate that cardiac MC are a source of fibrinolytic antigens and that accumulation of MC in auricular thrombosis is associated with phenotypic changes of MC and loss of cellular tPA. It is hypothesized that MC and their products may play a role in endogenous fibrinolysis in auricular thrombosis.

Immunophenotypic and functional characterization of human tonsillar mast cells

Mast cells (MC) are proinflammatory immune cells residing in various organs. Tissue-specific heterogeneity of MC has been described. The aim of this study was to establish the phenotype and functional profile of human tonsillar mast cells (ToMC) and to compare ToMC with lung-, skin-, and uterus MC. Tonsillar tissue was obtained from 23 patients suffering from hyperplastic tonsils and dispersed by enzymatic digestion. With the use of a combined toluidine blue/immunofluorescence staining technique, isolated ToMC were found to react with monoclonal antibodies (mAb) to immunoglobulin E, CD9, CD43, CD44, CD46, CD54, CD55, and CD59, as well as mAb to stem cell factor (SCF) receptor (CD117/c-kit). ToMC were not recognized by mAb to other cytokine receptors or mAb to CD3, CD11b, CD14, CDw17, the skin MC marker CD88 (C5aR) or CD89 (Fc alphaR). Activation of ToMC by recombinant human (rh) SCF or anti-IgE resulted in histamine secretion, whereas no effects were seen with rhC5a, rh granulocyte-macrophage colony-stimulating factor, or rh interleukin-1 through -10. In summary, ToMC exhibit functional and phenotypic properties similar to lung- or uterus MC. Unlike skin MC, ToMC lack C5aR and are unresponsive to rhC5a.

Molecular and functional characterization of the urokinase receptor on human mast cells

The urokinase receptor system is involved in several biological processes including extracellular proteolysis, cell invasion, and chemotaxis. Mast cells are multifunctional perivascular cells that play an important role in the regulation of microenvironmental events. We report that primary human mast cells and the human mast cell line HMC-1 express the receptor for urokinase. As assessed by Northern blotting and reverse transcription polymerase chain reaction technique, purified human lung mast cells and HMC-1 cells expressed urokinase receptor mRNA in a constitutive manner. Using a toluidine blue/immunofluorescence double staining technique and monoclonal antibodies, surface expression of urokinase receptor was demonstrable in lung, skin, uterus, heart, and tonsil mast cells, whereas the low density lipoprotein receptor-related protein was not detectable. Binding of monoclonal antibody VIM5 (recognizing the urokinase binding domain of urokinase receptor) to HMC-1 could be blocked by high molecular weight but not low molecular weight urokinase. Binding analyses performed with 123I-urokinase revealed expression of 271,000 +/- 55,000 high affinity urokinase binding sites per HMC-1 cell, with a calculated dissociation constant of 1. 29 +/- 0.3 nM. Purified urokinase induced dose-dependent migration of primary mast cells and HMC-1 in a chemotaxis assay without inducing release of histamine. The mast cell agonist stem cell factor also induced migration of HMC-1 and caused up-regulation of expression of urokinase receptor mRNA. Together, our data show that human mast cells express functional receptors for urokinase. Expression of urokinase receptors on mast cells may have implications for mast cell-dependent microvascular processes associated with fibrinolysis, migration, or local tissue repair.

Sudden, unexpected death of a young marathon runner as a result of bronchial malformation

Deaths of young athletes are mainly caused by cardiac problems. Noncardiac deaths are infrequent and related to heat stress, drugs, sickle cell trait, and asthma. Herein, we report the case of a 28-year-old man, who collapsed during a marathon race, within sight of the finish line. Despite immediate resuscitation, he died shortly after hospitalization. Autopsy findings revealed neither unambiguous cardiac nor previously published noncardiac causes. Traumatic or drug-related death was excluded as well. We did find, however, focally hyperinflated pulmonary areas adjacent to atelectasis, interstitial emphysema, and mucosal infoldings of several bronchi. Histologically, two-thirds of medium-sized bronchi presented paucity of cartilages. Hence, the resulting flaccidity of the bronchial wall might cause bronchial obstruction, which we related to the genesis of this sudden and unexpected death.

Vascular endothelial growth factor production in normal epidermis and in benign and malignant epithelial skin tumors

Vascular endothellal growth factor (VEGF) increases vascular permeability and acts as a mitogen for endothelial cells in vivo and in vitro. We and others recently demonstrated that cultured human keratinocytes constitutively secrete VEGF. In the present study, we examined the expression of this growth factor in various epithelial skin tumors and in normal skin. Using in situ hybridization, we detected strong VEGF mRNA expression in all of 10 squamous cell carcinomas, 13 common warts, 11 seborrheic keratoses, and in 7 of 8 keratoacanthomas studied. By contrast, we found no VEGF mRNA in 9 of 14 basal cell carcinomas. VEGF mRNA was readily detectable within the epidermis adjacent to the tumors as well as in tumor cells and in the epidermis of normal human skin. Northern hybridization of RNA derived from normal human epidermis identified VEGF transcripts of 3.7 and 1.8 kb, and reverse transcriptase polymerase chain reaction confirmed that epidermal cells, like keratinocytes in vitro, express the three major splice forms of VEGF. Immunohistochemical staining with monoclonal antibodies confirmed that expression of VEGF mRNA was accompanied by the presence of VEGF protein. Our data demonstrate that VEGF production by tumor cells in situ does not distinguish malignant from benign epithelial tumors of the skin because it is present in both. The constitutive expression of VEGF by normal keratinocytes in situ suggests that this angiotropic cytokine is important for the regulation of vessel function under physiologic conditions.

Stem cell factor-induced downregulation of c-kit in human lung mast cells and HMC-1 mast cells

Recent data suggest that local overexpression of the tissue-hormone c-kit ligand (stem cell factor [SCF]) is associated with accumulation of mast cells (MCs) and a decrease in expression of c-kit in the accumulated MCs [28]. In the present study, the effects of recombinant human (rh) SCF on expression of c-kit mRNA and c-kit protein in isolated human MCs and a human mast cell line, HMC-1, were analyzed. Incubation of isolated lung MC with rhSCF (100 ng/mL) for 120 minutes resulted in decreased expression of c-kit mRNA (optical density [OD], control: 100% vs. rhSCF: 37%). Almost identical results were obtained with HMC-1 cells (OD, control: 100% vs. rhSCF: 40 to 45%). As assessed by flow cytometry and monoclonal antibodies (mAbs) to c-kit, the SCF-induced decrease of c-kit mRNA in HMC-1 was associated with a substantial decrease in surface expression of c-kit (MFI, control: 100 +/- 21%, vs. MFI in cells incubated with rhSCF [100 ng/mL at 37 degrees C for 12 hours]: 8 +/- 2%, vs. MFI in cells incubated with rhSCF, 100 ng/mL, at 4 degrees C: 34 +/- 3%). The effects of rhSCF on c-kit expression in HMC-1 cells were dose- and time-dependent with maximum effects observed with 10-100 ng/mL of rhSCF after 4 to 12 hours. The SCF-dependent loss of c-kit was also accompanied by a decreased chemotactic response to rhSCF (control: 100%; rhSCF: 71 +/- 2%). This study shows that exposure of human lung MC and HMC-1 cells to recombinant SCF results in downregulation of c-kit mRNA and surface c-kit expression. These data may explain the partial loss of c-kit on MCs in areas of SCF overexpression.

Effects of cyclosporin A and FK-506 on stem cell factor-induced histamine secretion and growth of human mast cells

Stem cell factor (SCF) is a key regulator of human mast cells (MCs) and a potential mediator of allergy. In this study the effects of cyclosporin A (CSA) and FK-506, two potent immunosuppressive drugs, on SCF-dependent histamine release and growth of human MCs were analyzed. Preincubation of tissue MCs with CSA (3 micrograms/ml) resulted in inhibition of histamine release provoked by either recombinant human (rh) SCF (70.3% +/- 20.6% inhibition, p < 0.001) or anti-IgE (76.7% +/- 21.9%, p < 0.001) or by rhSCF+ anti-IgE (77.4% +/- 13.9%, p < 0.001). Almost the same inhibition was produced by FK-506 (rhSCF: 82.0% +/- 18.9% inhibition, p < 0.001; anti-IgE: 71.5% +/- 16.7%, p < 0.001; rhSCF+ anti-IgE: 70.0% +/- 7.3%, p < 0.001). The effects of CSA and FK-506 on SCF-dependent release of histamine were dose-dependent (IC50: CSA, 1 to 10 ng/ml; FK-506, 0.3 to 3 ng/ml). IC50 values about three to 10 times higher were found for MCs preincubated with rhSCF before anti-IgE activation, compared with anti-IgE or SCF alone. SCF-dependent differentiation of human MCs was analyzed in a long-term suspension culture system (n = 6). Unexpectedly, CSA and FK-506 were unable to suppress, but even enhanced SCF-dependent growth of MCs and formation of MC tryptase in long-term culture. Together, CSA and FK-506 inhibit SCF-dependent release of histamine from human MCs and even augment SCF-dependent growth of human MCs in long-term culture.

Mast cell-lineage versus basophil lineage involvement in myeloproliferative and myelodysplastic syndromes: diagnostic role of cell-immunophenotyping

Mast cells and blood basophils are distinct hemopoietic cells. They can be distinguished from each other and from all other lymphohemopoietic cells using antibodies against surface receptors or stored cytoplasmic molecules. In patients with myelodysplastic syndromes (MDS) or myeloproliferative syndromes (MPS), an elevation of metachromatically granulated cells (MCS) is frequently seen. These cells can be classified as basophils or mast cells using monoclonal antibodies (mAbs) against leukocyte antigens, including mast cell tryptase, c-kit (= mast cell growth factor [MGF] receptor), interleukin-3 receptor alpha chain (IL-3R alpha = CD123), and CD11b (C3biR). In a stable phase of MDS or MPS, the circulating MCS usually are basophils (histamine+, tryptase-, c-kit-, IL-3R alpha +, CD11b+). In an accelerated or terminal phase of disease, however, mast cell lineage involvement and circulating mast cell precursors (histamine+, tryptase+, c-kit+, IL-3R alpha-, CD11b-) are found in a subset of patients. The use of mAbs against mast cell antigens and granulocyte antigens is diagnostic in these patients.

Comparative immunophenotypic analysis of human mast cells, blood basophils and monocytes

Mast cells (MC), blood basophils (Ba) and monocytes (Mo) are of haemopoietic origin. Lineage-relationships and transdifferentiation between MC and Mo, or MC and Ba, have been considered, based on common expression of antigens. In this study, comparative phenotypic analyses on MC, Ba and Mo and on respective cell lines were performed using monoclonal antibodies (mAb) to previously defined and novel CD antigens (CD1-130). By cluster analysis, the overall (all 130 CD) phenotypic relationships (given as similarity indices, SI), between primary cells (MC, Ba and Mo) and corresponding cell lines (HMC-1, KU-812, U937) were 0.716, 0.779 and 0.757, respectively. When primary cells were compared, lower SI values were found (MC versus Ba, 0.509; MC versus Mo, 0.625; Mo versus Ba, 0.698). More distant relationships were found between MC versus Ba and MC versus Mo, compared with Ba versus Mo, for adhesion receptor (R)-, complement R- and cytokine R profiles. Analysis of cytokine R revealed most significant dissimilarities between MC versus Ba and MC versus Mo (SI < 0.2). Moreover, in contrast to other CD subgroups and other lineages, MC and HMC-1 differed from each other in cytokine R expression (SI = 0.286). Cytokine R detectable on HMC-1 but not MC were granulocyte-macrophage colony-stimulating factor (GM-CSFR)alpha(CD116), CD40, Apo-1/FAS(CD95) and gp130(CD130). Cytokine R detectable on Ba but not MC, were interleukin-3 (IL-3)R alpha(CD123), IL-1RII(CD121b), IL-2R alpha(CD25) and CD40. In summary, MC, Ba and Mo display a unique CD profile with MC being the most distantly related cell. The most significant mismatch within a given lineage is the loss of cytokine R on mature MC as compared with normal myeloid progenitors and HMC-1 cells.

Detection of anti-neutrophil cytoplasmic antibodies after acute Plasmodium falciparum malaria

Four of 30 patients with Plasmodium falciparum infection in Bangkok, Thailand, were positive for anti-neutrophil cytoplasmic antibodies by indirect immunofluorescence 1 month after antimalarial therapy. No myeloperoxidase, proteinase 3, lactoferrin, or elastase reactivity was found. Since no evidence of vasculitis was seen in these patients, anti-neutrophil cytoplasmic antibody production in malaria-infected susceptible patients probably represents a secondary response, indicating neutrophil activation.

Differential expression of complement receptors on human basophils and mast cells. Evidence for mast cell heterogeneity and CD88/C5aR expression on skin mast cells

Complement-dependent activation of immune cells is regulated by cell surface membrane receptors. In this study, expression of complement receptors (CR) on human blood basophils (n = 11), tissue mast cells (lung, n = 7; skin, n = 10; uterus, n = 4; tonsil, n = 3; heart, n = 10), and on respective human cell lines (basophil line KU-812, mast cell line HMC-1) was analyzed by the use of mAbs and indirect immunofluorescence. Normal blood basophils and KU-812 cells were found to express C5aR (CD88), membrane cofactor protein (CD46), decay-accelerating factor (CD55), and membrane attack complex inhibitory factor (CD59), as well as the previously recognized CR1 (CD35), CR3 alpha (CD11b), CR4 alpha (CD11c), and CR3/4 beta (CD18). Mast cells from all organs as well as HMC-1 cells expressed CD46, CD55, and CD59, but not CD11b, CD21, or CD35. The C5aR (CD88) was detectable on skin mast cells, a subset (5 to 15%) of cardiac mast cells, and on HMC-1 cells, but not on lung, uterus, or tonsillar mast cells (< 5%). Moreover, double immunoperoxidase staining (tryptase vs C5aR/CD88) revealed in situ expression of C5aR on skin, but not lung mast cells. Recombinant human (rh) C5a, at 10(-10) to 10(-7) M, induced secretion of histamine from basophils (rhC5a, 10(-8) M: 53.4 +/- 3.1% vs control < 5%) and from skin mast cells (rhC5a, 10(-8) M: 25.8 +/- 16.1% vs control < 10% histamine release), but not from other mast cells (rhC5a or control: < 10%, p > 0.05). The rhC5a-induced secretion of histamine from basophils and skin mast cells was inhibited by S5/1, a blocking Ab against CD88 (basophils: 37.2% to 75.1%; skin mast cells: 39.2% to 83.9% inhibition, p < 0.05). Together, this study shows that a) basophils and mast cells express a different profile of complement receptors, b) C5a-dependent mediator release in skin mast cells and basophils is mediated via CD88, and c) mast cells constitute a heterogeneous lineage in terms of expression of the C5a binding site CD88.

Differential expression of complement receptors on human basophils and mast cells. Evidence for mast cell heterogeneity and CD88/C5aR expression on skin mast cells

Complement-dependent activation of immune cells is regulated by cell surface membrane receptors. In this study, expression of complement receptors (CR) on human blood basophils (n = 11), tissue mast cells (lung, n = 7; skin, n = 10; uterus, n = 4; tonsil, n = 3; heart, n = 10), and on respective human cell lines (basophil line KU-812, mast cell line HMC-1) was analyzed by the use of mAbs and indirect immunofluorescence. Normal blood basophils and KU-812 cells were found to express C5aR (CD88), membrane cofactor protein (CD46), decay-accelerating factor (CD55), and membrane attack complex inhibitory factor (CD59), as well as the previously recognized CR1 (CD35), CR3 alpha (CD11b), CR4 alpha (CD11c), and CR3/4 beta (CD18). Mast cells from all organs as well as HMC-1 cells expressed CD46, CD55, and CD59, but not CD11b, CD21, or CD35. The C5aR (CD88) was detectable on skin mast cells, a subset (5 to 15%) of cardiac mast cells, and on HMC-1 cells, but not on lung, uterus, or tonsillar mast cells (&lt; 5%). Moreover, double immunoperoxidase staining (tryptase vs C5aR/CD88) revealed in situ expression of C5aR on skin, but not lung mast cells. Recombinant human (rh) C5a, at 10(-10) to 10(-7) M, induced secretion of histamine from basophils (rhC5a, 10(-8) M: 53.4 +/- 3.1% vs control &lt; 5%) and from skin mast cells (rhC5a, 10(-8) M: 25.8 +/- 16.1% vs control &lt; 10% histamine release), but not from other mast cells (rhC5a or control: &lt; 10%, p &gt; 0.05). The rhC5a-induced secretion of histamine from basophils and skin mast cells was inhibited by S5/1, a blocking Ab against CD88 (basophils: 37.2% to 75.1%; skin mast cells: 39.2% to 83.9% inhibition, p &lt; 0.05). Together, this study shows that a) basophils and mast cells express a different profile of complement receptors, b) C5a-dependent mediator release in skin mast cells and basophils is mediated via CD88, and c) mast cells constitute a heterogeneous lineage in terms of expression of the C5a binding site CD88.

Serum levels of the carboxy-terminal cross-linked telopeptide of type I collagen and laminin are elevated in Graves' disease but not in toxic nodular goiter

We determined serum levels of laminin, carboxy-terminal cross-linked telopeptide, and carboxy-terminal propeptide of type I collagen (ICTP and PICP) in 27 patients with Graves' disease (GD) and in 31 patients with toxic nodular goiter (TNG). Elevated levels of soluble laminin and ICTP were observed in patients with GD prior to treatment (mean +/- SD concentration 1444 +/- 404 and 8.6 +/- 3.5 ng/ml, respectively), compared to patients with TNG (476 +/- 103 and 4.2 +/- 1.5 ng/ml) and normal controls (492 +/- 112 and 3.1 +/- 1.3 ng/ml, n = 34). In contrast, serum PICP concentrations were not different between patients with GD or TNG and normal controls. In GD patients serum ICTP and laminin levels decreased during thiamazole treatment and normalized within 4 and 8 weeks of therapy. There was no correlation between serum ICTP and laminin levels and serum levels of thyroid hormones and/or autoantibodies, respectively. Serum ICTP and laminin could be markers for alterations of extracellular matrix during GD and release of matrix components in the circulation and/or reflect an impaired clearance.

Purification of human basophils and mast cells by multistep separation technique and mAb to CDw17 and CD117/c-kit

Basophils and mast cells represent distinct cell lineages within the hemopoietic system. Based on the unique cell surface antigen profile of both cells, we have established methods which allow the reproducible purification to homogeneity (> 99%) of normal human basophil granulocytes from the peripheral blood and of mast cells from human dispersed tissues. Basophils (n = 9) were purified by current counterflow elutriation followed by depletion of monocytes with CD14 mAb conjugated to magnetic beads, and subsequent cell sorting for CD217+ cells. Basophil purity was 99.5 +/- 0.4% (range 98.7-99.9%). Mast cells were obtained from lung (n = 6), uterus (n = 1), mastocytosis bone marrow (n = 2), and human foreskin (n = 2). Mast cells were purified by collagenase digestion followed by current counterflow elutriation and sorting with CD117/c-kit mAb. Mast cell purity was 99.4 +/- 0.7% (range: 97.5-99.9%). Purified cells were more than 90% viable and were able to release histamine on induction with IgE plus anti-IgE. Furthermore, the PCR technique could be applied on pure cells and confirmed expression of high affinity IgE receptor (Fc epsilon R1) alpha chain mRNA. Thus, by combining isolation techniques including elutriation, magnetic cell depletion and cell sorting with mAb, functionally intact normal human basophils and mast cells can be enriched to homogeneity.

Increase and redistribution of cardiac mast cells in auricular thrombosis. Possible role of kit ligand

BACKGROUND

The atrial appendage is a predilection site for thrombus formation. Mast cells (MC) are a rich source of mediators that may be involved in the regulation of thrombus formation. We examined number, distribution, and phenotype of MC in thrombosed versus unaffected auricles to elucidate their possible role in auricular thrombosis (AUTHR).

METHODS AND RESULTS

Sections of atrial appendages (AUTHR, n = 14; controls (CO), n = 13) were analyzed for MC by Giemsa, toluidine blue, and berberine sulfate stains and by immunohistochemistry. Cardiac MC expressed CD antigens corresponding to the classic MC phenotype as well as tryptase, chymase, and heparin. Thrombosis was associated with a twofold increase in the number of MC in the total appendage (CO, 3.1 +/- 1.0 versus AUTHR, 6.4 +/- 1.1 MC/mm2, P < .01). Moreover, in AUTHR, a redistribution of MC to the upper endocardium was observed (AUTHR, 5.3 +/- 1.4 versus CO, 0.07 +/- 0.15 MC/mm2, P < .01). Mast cell growth factor (MGF) was expressed in the endothelium and subendothelial space of thrombosed appendages but not in the normal endocardium. Overexpression of MGF was accompanied by a weak or absent expression of the MGF receptor c-kit on redistributed MC in AUTHR. Patients with unilateral atrial appendage thrombosis did not exhibit a MC increase or redistribution in the unaffected contralateral appendage. No augmentation of other inflammatory cells was observed. Stimulation of isolated cardiac MC with MGF resulted in mediator release.

CONCLUSIONS

This study provides evidence that AUTHR is associated with MC increase and redistribution and MGF overexpression. The role of redistributed MC and their mediators in the pathophysiology of atrial thrombosis requires further investigation.

Kit ligand/mast cell growth factor-independent differentiation of mast cells in myelodysplasia and chronic myeloid leukemic blast crisis

Autonomous, factor-independent growth and differentiation of malignant cells in preleukemic and leukemic disease states is a well-recognized phenomenon and is often associated with a poor prognosis. Mast cells are distinct hematopoietic cells and express a unique profile of antigens. Growth and differentiation of normal mast cells is dependent on mast cell growth factor (MGF), the ligand of the c-kit protooncogene product. In this study, we screened for mast cell-lineage involvement in 52 patients suffering from myeloid leukemias, myelodysplastic syndromes (MDS), systemic mastocytosis, or other diseases by probing for mast cell-related molecules (c-kit, tryptase, histamine, and MGF) and by analyzing kit ligand/MGF-independent growth of mast cells in long-term suspension culture. Of the 52 patients tested, 2 patients with refractory anemia with excess of blast cells in transformation and 1 patient suffering from chronic myeloid leukemia blast crisis (CML-BC) were diagnosed as mastocytic disease. These patients were characterized by complex chromosomal abnormalities, splenomegaly, high percentages of circulating metachromatic cells (5% to 25%), high levels of cellular tryptase (> 10 ng/10(5) peripheral blood mononuclear cells/mL) and a tryptase/histamine (ng:ng) ratio greater than 1. The metachromatic cells expressed the mast-cell-related surface antigen c-kit, but not basophil-related antigens (CD11b, CDw17). Furthermore, in these 3 patients, spontaneous, MGF-independent growth of mast cells along with spontaneous synthesis of tryptase was demonstrable in long-term culture. No autocrine production, paracrine production, or overproduction of MGF was found. The spontaneous growth of mast cells could neither be abbrogated by addition of monoclonal antibodies (MoAbs) to c-kit nor by MoAbs against MGF (< 5% inhibition), whereas factor (MGF)-dependent differentiation of mast cells in these patients could be abbrogated by MoAbs to c-kit or MoAbs to MGF (> 70% inhibition, P < .001). In addition, serum MGF levels in these patients were within the normal range and MGF could not be detected in cell-free culture supernatants. All 3 patients showed rapid progression of disease and had a survival time of less than 1 year. In conclusion, we describe a unique form of transformation in MDS and CML-BC characterized by mast cell lineage involvement and factor-independent differentiation of mast cells. This form of leukemic transformation has to be delineated from chronic myeloid leukemia with basophilia or basophil crisis, from primary mast cell leukemia, and from monocytic leukemias and myelodysplastic disorders associated with basophilia.

The human cardiac mast cell: localization, isolation, phenotype, and functional characterization

We have isolated and characterized the human cardiac mast cell (CMC) and compared this novel mast cell (MC type with MC obtained from uterus, skin, and lung. Heart tissue was obtained from 14 patients with cardiomyopathy (CMP, heart transplantation). CMC were isolated by enzymatic digestion using collagenase, pronase-E, hyaluronidase, and DNAse. Substantial amounts of CMC (0.5% to 1.5% of isolated cells) were found in the atrial appendages but not in ventricular digests or other sites of the heart (< 0.1%). In situ staining of atrial tissue revealed the presence of CMC in the myocardium (2.16 +/- 0.7 MC/mm2), endocardium (2.24 +/- 0.9 MC/mm2), and epicardium. As assessed by combined toluidine blue/immunofluorescence staining with monoclonal antibodies (MoAbs), isolated CMC expressed surface IgE, the receptor for stem cell factor (c-kit receptor/CD117), the p24 antigen (CD9), the Pgp-1 homing receptor (CD44), the pan leukocyte antigen (CD45), and the ICAM-1 antigen (CD54). CMC were not recognized by MoAbs to lymphocyte function associated antigen 2 (LFA-2; CD2), T-cell receptor (TcR; CD3), T4 antigen (CD4), LFA-1 alpha-chain (CD11a), C3biR alpha-chain (CD11b), CR4 alpha-chain (CD11c), LPS-R related Ag (CD14), 3-FAL/x-hapten (CD15), Fc gamma RIII (CD16), lactosylceramid (CDw17), the B-cell antigen CD19, or CR1 (CD35). In situ expression of leukocyte antigens on CMC was demonstrable by indirect immunoperoxidase staining technique and double-labeling immunohistochemistry. Almost all CMC (90%) reacted with MoAbs against tryptase and chymase and thus were MCTC. Cardiac mast cells were also stained by the heparin-binding dye Berberine sulfate and expressed measurable amounts of histamine (4.6 +/- 1.4 pg per cell). Cross linking of either IgE receptor or SCF receptor (c-kit) on CMC resulted in histamine secretion (non-specific release: < 6% of total histamine, alpha IgE induced: 12% to 52%; SCF-induced release: 9% to 18%), whereas neither substance P (a skin MC agonist) nor the basophil agonist FMLP showed an effect on CMC. Together, the CMC is an MCTC primarily located in the appendage of the atrium. This novel type of MC exhibits surface membrane antigen and functional properties similar to those of lung and uterus MC.