First-line daratumumab shows high efficacy and tolerability even in advanced AL amyloidosis: the real-world experience

Background

Daratumumab was the first monoclonal CD38 antibody with single-agent activity approved for the treatment of multiple myeloma. Moreover, daratumumab demonstrated high response rates in relapsed immunoglobulin light-chain (AL) amyloidosis.

Patients and methods

In our single-center retrospective real-life case series, we analyzed the efficacy and safety of daratumumab as first-line treatment. Daratumumab was administered with low-dose dexamethasone alone or in combination with other multiple myeloma therapeutics

Results

Fourteen patients were eligible, including nine patients with cardiac stage IIIa or IIIb. Overall hematologic response rate was 100%, with 64.3% achieving complete response after a median of 16 cycles of treatment. Median time to hematologic response was 1.4 months. Organ response rates were 45.5% after a median of 4.0 months and 66.7% after a median of 10.0 months, for heart and kidney involvement, respectively. After a median follow-up of 20.5 months, two patients underwent successful autologous stem cell transplantation (ASCT), while another three patients were in preparation for ASCT. Three patients remained on daratumumab at the last follow-up. There were no unexpected toxicities and no grade III or IV adverse events, although more than half of our patients were in stage IIIa or IIIb.

Conclusion

Daratumumab proved to be highly effective in newly diagnosed AL amyloidosis with excellent hematologic and organ response rates, a remarkable safety profile, and good tolerability even in patients with advanced stage of disease.

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Daratumumab yields high hematologic response rates in untreated AL amyloidosis.

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Treatment is well tolerated even in advanced disease stages.

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No unexpected toxicity was observed.

P2727Hemodynamic profiles in patients with cardiac amyloidosis

Background

Intracardiac filling and pulmonary arterial pressures play a central role in various heart failure entities, as they are strong predictors of outcome. However, their role in patients with cardiac amyloidosis (CA) is less clear.

Purpose

We aimed to characterize hemodynamic profiles of CA patients and assess their association with outcomes.

Methods

The present study was conducted within a prospective, national CA registry.

Patients underwent invasive hemodynamic, clinical, laboratory, and echocardiography assessment, as well cardiac magnetic resonance imaging with T1-mapping. The main outcome measure was a combined endpoint consisting of hospitalization for heart failure or cardiovascular death.

Results

Between March 2012 and October 2018, 63 consecutively recruited CA patients underwent invasive hemodynamic profiling. Of those, 36 had cardiac transthyretin amyloidosis (ATTR) and 25 cardiac light-chain amyloidosis (AL). In two patients amyloid subtyping was not possible.

Median age of the study population was 74.0 years and the majority were male (61.9%). Almost half of the patients were in New York Heart Association (NYHA) class ≥III (47.6%) and showed elevated N-terminal prohormone of brain natriuretic peptides (NT-proBNP) with a median of 3222 pg/mL. In comparison to AL, cardiac TTR patients were older (75.0 years versus 69.0 years, p=0.004), more often male (80.6% versus 40.0%, p=0.001), less symptomatic (NYHA class ≥III: 38.9% versus 64.0%, p=0.021), and had lower NT-proBNP values (2324pg/mL versus 5151pg/mL, p=0.004).

Hemodynamic profiling revealed significantly increased intracardiac as well as pulmonary arterial pressures (PAP). On an average, pulmonary artery wedge pressure was 20.0mmHg [interquartile range (IQR): 17.0–25.0], mean PAP (mPAP) was 30.0mmHg (IQR: 25.0–37.0), and mean right atrial pressure (mRAP) was 11.0mmHg (IQR: 7.0–16.0). No differences between ATTR and AL patients could be detected (p=0.148, p=0.398, p=0.620). During a median follow-up of 63.0 weeks, 28 study participants (44.4%) reached the combined endpoint. Moreover, cardiac AL patients had significantly more events as their ATTR counterparts (72.0% versus 27.8%, p=0.001). In cardiac ATTR patients, mPAP was significantly associated with outcome [hazard ratio (HR): 1.083, p=0.034, Figure 1A], which was not the case in the AL group (HR: 1.024, p=0.186, Figure 1B). Cardiac output and pulmonary vascular resistance were not associated with outcome. Neither in the ATTR (p=0.144; p=0.063) nor in AL cohort (p=0.420; p=0.115).

Figure 1

Conclusion

Despite differences in the severity of symptoms between cardiac AL and cardiac ATTR patients, no differences with regards to hemodynamic profiles could be detected.

Furthermore, intracardiac filling and pulmonary arterial pressures seem to be of greater clinical importance in cardiac ATTR as compared to cardiac AL, as these parameters were associated with outcome in the first, but not the latter group.

P895Apical sparing in patients without cardiac amyloidosis

Background

Apical sparing describes a reduced longitudinal strain in the basal segments and preserved or supranormal longitudinal strain in the apical segments of the left ventricular (LV) myocardium. This pattern has been described as a typical finding in patients with cardiac amyloidosis (CA) and restrictive cardiomyopathy. However, apical sparing is not a quantitative parameter and is fairly subjective to the echocardiographer's judgement. It is not known, if a certain degree of apical sparing is also present in patients with only mild LV hypertrophy and diastolic dysfunction such as it is present in heart failure with preserved ejection fraction (HFpEF).

Methods

Patients with cardiac transthyretin and light chain amyloidosis and patients with HFpEF were included in a clinical registry at our outpatient clinic. CA was diagnosed according to current guidelines. All patients underwent a comprehensive transthoracic echocardiography (TTE) exam at the time of study inclusion. The TTE protocol included standard and speckle-tracking imaging to assess the presence of apical sparing as well as the basal to apical strain gradient. Patients with known coronary artery disease were excluded.

Results

In total 115 patients were included in this study. Of these, 87 (75.7%) were diagnosed with CA and 28 (24.3%) with HFpEF. Not surprisingly, apical sparing was found in a majority (86.2%) of patients with CA, however mild forms of this phenomenon were also present in 67.9% of patients with HFpEF (p=0.029, Figure 1). Median basal longitudinal strain was significantly more impaired in patients with CA (p<0.001) but there was no difference between longitudinal strain in the apical segments when comparing CA to HFpEF (p=0.443). This resulted in a higher median apical to basal strain gradient in patients with CA (2.3 (IQR 1.7–3.83) versus 1.13 (IQR 1.5–1.8), p<0.001).

Figure 1

Conclusion

Mild forms of apical sparing can be found in patients without CA. Gradual reduction in strain from base to apex could be an unspecific pathophysiologic mechanism which is remarkably pronounced in patients with CA.

P2726Extremely boosted prediction of cardiac amyloidosis by routine laboratory paramaters

Background/Introduction

Cardiac amyloidosis (CA) is a rare and complex condition with poor prognosis. Novel therapies have been shown to improve outcome, however, most of the affected individuals remain undiagnosed, mainly due to a lack in awareness among clinicians. One approach to overcome this issue is to use automated diagnostic algorithms that act based on routinely available laboratory results.

Purpose

We tested the performance of flexible machine learning and traditional statistical prediction models for non-invasive CA diagnosis based on routinely collected laboratory parameters. Since laboratory routines vary between hospitals or other health care providers, special attention has been taken to adaptive and dynamic parameter selection, and to dealing with the frequent occurrence of missing values.

Methods

Our cohort consisted of 376 clinically accepted patients with various types of heart failure. Of these, 69 were diagnosed with CA via endomyocardial biopsy (positives), and 307 had unrelated cardiac disorders (negatives). A total of 63 routine laboratory parameters were collected from these patients, with a high incidence of missing values (on average 60% of patients for each parameter). We tested the performance of two prediction models: logistic regression, and extreme gradient boosting with regression trees. To deal with missing values we adopted two strategies: a) finding an optimal overlap of parameters and deleting all patients with missing values (reduction of parameters and samples), and b) retaining all features and imputing missing values with parameter-wise means. To fairly assess the performance of prediction models we employed a 10-fold cross validation (stratified to preserve sample class ratio). Finally, area under curve for receiver-operator characteristic (ROC AUC) was used as our final performance measure.

Results

A complex machine learning model based on forests of regression trees proved to be the most performant (ROC AUC 0.94±4%) and robust to missing values. The best regression model was obtained with the 25 most frequent variables and patient deletion in case of missing values (ROC AUC 0.82±0.8%). While progressive inclusion of predictor variables worsened the performance of the logistic regression, it increased that of the machine learning approach.

Conclusions

Extreme gradient boosting of regression trees by routine laboratory parameters achieved staggering accuracy results for the automated diagnosis of CA. Our data suggest that implementations of such algorithms as independent interpreters of routine laboratory results may help to establish or suggest the diagnosis of CA in patients with heart failure symptoms, even in the absence of specialized experts.

Formation of spheroids by dental pulp cells in the presence of hypoxia and hypoxia mimetic agents

AIM

To evaluate the impact of hypoxia and hypoxia mimetic agents (HMA) on the formation and activity of spheroids by dental pulp cells (DPC).

METHODOLOGY

DPC on agarose-coated plates were treated with hypoxia and the HMA dimethyloxallyl glycine (DMOG), desferrioxamine (DFO) and L-mimosine (L-MIM). Images of spheroids were taken directly after seeding and at 6 h and 24 h. Spheroid sizes were quantified by area measurement with ImageJ software. Viability was assessed with Live-Dead staining, MTT and resazurin-based toxicity assay. Production of VEGF, IL-8 and SDF-1 was evaluated using immunoassays. Data were analysed using Kruskal-Wallis test and post hoc Mann-Whitney U-test.

RESULTS

DPC formed spheroids in the presence of hypoxia, HMA and combined treatment with hypoxia and HMA. No pronounced difference in spheroid size was found in the groups treated with hypoxia, DMOG, DFO, L-MIM and the combination of hypoxia and the HMA relative to their normoxic controls (P > 0.05). Spheroids appeared vital in Live-Dead and MTT staining and the resazurin-based toxicity assay. Evaluation of protein production with immunoassays revealed significantly enhanced levels of VEGF and IL-8 (P < 0.05), but there was no significant effect on SDF-1 production (P > 0.05). Treatment with a combination of hypoxia and HMA did not further boost VEGF and IL-8 production (P > 0.05).

CONCLUSIONS

Pre-conditioning with hypoxia and HMA increased the pro-angiogenic capacity of spheroids whilst not interfering with their formation. Pre-clinical studies will reveal whether pre-conditioning of spheroids with hypoxia and HMA can effectively improve the efficiency of cell transplantation approaches for regenerative endodontics.

L-mimosine increases the production of vascular endothelial growth factor in human tooth slice organ culture model

AIM

To assess the pro-angiogenic and pro-inflammatory capacity of the dentine-pulp complex in response to the prolyl hydroxylase inhibitor L-mimosine in a tooth slice organ culture model.

METHODOLOGY

Human teeth were sectioned transversely into 600-μm-thick slices and cultured in medium supplemented with serum and antibiotics. Then, pulps were stimulated for 48 h with L-mimosine. Pulps were subjected to viability measurements based on formazan formation in MTT assays. In addition, histological evaluation of pulps was performed based on haematoxylin and eosin staining. Culture supernatants were subjected to immunoassays for vascular endothelial growth factor (VEGF) to determine the pro-angiogenic capacity and to immunoassays for interleukin (IL)-6 and IL-8 to assess the pro-inflammatory response. Interleukin-1 served as pro-inflammatory control. Echinomycin was used to inhibit hypoxia-inducible factor-1 (HIF-1) alpha activity. Data were analysed using Student's t-test and Mann-Whitney U test.

RESULTS

Pulps within tooth slices remained vital upon L-mimosine stimulation as indicated by formazan formation and histological evaluation. L-mimosine increased VEGF production when normalized to formazan formation in the pulp tissue of the tooth slices (P < 0.05). This effect on VEGF was reduced by echinomycin (P < 0.01). Changes in normalized IL-6 and IL-8 levels upon treatment with L-mimosine did not reach the level of significance (P > 0.05), whilst treatment with IL-1, which served as positive control, increased IL-6 (P < 0.05) and IL-8 levels (P < 0.05).

CONCLUSIONS

The prolyl hydroxylase inhibitor L-mimosine increased VEGF production via HIF-1 alpha in the tooth slice organ culture model whilst inducing no prominent increase in IL-6 and IL-8. Pre-clinical studies will reveal if these in vitro effects translate into dental pulp regeneration.

Prolyl hydroxylase inhibitors increase the production of vascular endothelial growth factor by periodontal fibroblasts

BACKGROUND AND OBJECTIVE

Pharmacological inhibitors of prolyl hydroxylases (PHDs) can induce a proangiogenic response that favors wound healing and bone regeneration. However, the response of periodontal cells to PHD inhibitors is unknown.

MATERIAL AND METHODS

To determine the effects of PHD inhibitors on periodontal cells, we exposed human fibroblasts from the gingiva and the periodontal ligament to dimethyloxallyl glycine, desferrioxamine, l-mimosine and CoCl(2). Viability, proliferation, and protein synthesis were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), [(3)H]thymidine, and [(3)H]leucine incorporation, respectively. The levels of Ki67, hypoxia-inducible factor 1α (HIF-1α), p27, phosphorylated c-Jun N-terminal kinase (JNK) and phosphorylated p38 were determined by immunohistochemistry and western blotting. Vascular endothelial growth factor (VEGF) mRNA levels were measured by quantitative PCR. Protein levels of VEGF and interleukin (IL)-6 were evaluated by immunoassays.

RESULTS

We found that PHD inhibitors, while leaving cell viability unchanged, reduced proliferation and protein synthesis. This was paralleled by decreased Ki67 levels and increased p27 levels, suggesting that PHD inhibitors provoke growth arrest. Independently from this response, PHD inhibitors stabilized HIF-1α and increased the production of VEGF. This increase of VEGF was observed in the presence of proinflammatory IL-1 and pharmacological inhibitors of JNK and p38 signaling. Moreover, PHD inhibitors did not modulate expression of IL-6 and the phosphorylation of JNK and p38.

CONCLUSION

These results suggest that PHD inhibitors enhance the production of VEGF in periodontal fibroblasts, even in the presence of proinflammatory IL-1. The data further suggest that PHD inhibitors do not provoke a significant proinflammatory or anti-inflammatory response in this in vitro setting.

The response of dental pulp-derived cells to zoledronate depends on the experimental model

AIM

To investigate whether zoledronate (ZOL) can cause a cytotoxic response in dental pulp-derived cells (DPCs) in vitro.

METHODOLOGY

Cell activity was assessed utilizing MTT tests, (3) [H]thymidine, and (3) [H]leucine incorporation assays in human DPCs in response to ZOL. Cell activity assays were also preformed on calcium phosphate-coated plates. Cell death was analysed with annexin V/propidium iodide, trypan blue staining and Western blot analysis.

RESULTS

Micromolar concentrations of ZOL were required to decrease the activity of DPCs. The decreased activity of DPCs was associated with the occurrence of apoptosis and necrosis. No adverse effects were observed when DPCs were cultured on calcium phosphate-coated plates with ZOL.

CONCLUSION

High concentrations of soluble ZOL were required to cause adverse effects in vitro. These adverse effects are abolished when the bisphosphonate was bound to a mineralized surface. However, the clinical relevance of these results remains to be determined.

The addition of plerixafor is safe and allows adequate PBSC collection in multiple myeloma and lymphoma patients poor mobilizers after chemotherapy and G-CSF

We report 13 multiple myeloma (MM) or lymphoma patients who were failing PBSC mobilization after disease-specific chemotherapy and granulocyte-CSF (G-CSF), and received plerixafor to successfully collect PBSCs. Patients were considered poor mobilizers when the concentration of PB CD34(+) cells was always lower than 10 cells/μL, during the recovery phase after chemotherapy and/or were predicted to have inadequate PBSC collection to proceed to autologous transplantation. Plerixafor (0.24 mg/kg) was administered subcutaneously for up to three consecutive days, while continuing G-CSF, 10-11 h before the planned leukapheresis. Plerixafor administration was safe and no significant adverse events were recorded. We observed a 4.7 median fold-increase in the number of circulating CD34(+) cells after plerixafor as compared with baseline CD34(+) cell concentration (from a median of 6.2 (range 1-12) to 21.5 (range 9-88) cells/μL). All patients collected >2 × 10(6) CD34(+) cells/kg in 1-3 leukaphereses. In all, 5/13 patients have already undergone autograft with plerixafor-mobilized PBSCs, showing a rapid and durable hematological recovery. Our results suggest that the pre-emptive addition of plerixafor to G-CSF after chemotherapy is safe and may allow the rescue of lymphoma and MM patients, who need autologous transplantation but are failing PBSC mobilization.

Is Zoledronate Toxic to Human Periodontal Fibroblasts?

Exposed necrotic alveolar bone is a hallmark of bisphosphonate-related osteonecrosis of the jaw. However, it is unknown whether zoledronate causes soft-tissue damage via adverse actions toward periodontal fibroblasts. We therefore examined whether zoledronate causes a cytotoxic response in fibroblasts isolated from the gingiva and the periodontal ligament. We report that micromolar concentrations of zoledronate and serum-free conditions decreased cell activity, as measured by assays for formazan formation, proliferation, and protein synthesis. Under these conditions, periodontal fibroblasts underwent apoptosis and necrosis, as indicated by cleavage of PARP and membrane disruption, respectively. However, these adverse effects of zoledronate were mitigated by the presence of serum. Moreover, zoledronate bound to calcium phosphate failed to reduce cell activity. Analysis of these data suggests that the cytotoxic responses of periodontal fibroblasts require high concentrations of zoledronate and depend on the in vitro experimental conditions. Whether these findings translate into soft-tissue damage will require further investigation.

Elevated tryptase levels selectively cluster in myeloid neoplasms: a novel diagnostic approach and screen marker in clinical haematology

BACKGROUND

Recent data suggest that tryptase, a mast cell enzyme, is expressed in neoplastic cells in myeloid leukaemias. In several of these patients, increased serum tryptase levels are detectable.

MATERIALS AND METHODS

We have determined serum tryptase levels in 914 patients with haematological malignancies, including myeloproliferative disorders (n = 156), myelodysplastic syndromes (MDS, n = 241), acute myeloid leukaemia (AML, n = 317), systemic mastocytosis (SM, n = 81), non-Hodgkin's lymphoma (n = 59) and acute lymphoblastic leukaemia (n = 26). Moreover, tryptase was measured in 136 patients with non-neoplastic haematological disorders, 102 with non-haematological disorders and 164 healthy subjects.

RESULTS

In healthy subjects, the median serum tryptase was 5.2 ng mL(-1). Elevated serum tryptase levels were found to cluster in myeloid neoplasm, whereas almost all patients with lymphoid neoplasms exhibited normal tryptase. Among myeloid neoplasms, elevated tryptase levels (> 15 ng mL(-1)) were recorded in > 90% of patients with SM, 38% with AML, 34% with CML and 25% with MDS. The highest tryptase levels, often > 1000 ng mL(-1), were found in advanced SM and core-binding-factor leukaemias. In most patients with non-neoplastic haematological disorders and non-haematological disorders analysed in our study, tryptase levels were normal, the exception being a few patients with end-stage kidney disease and helminth infections, in whom a slightly elevated tryptase was found.

CONCLUSIONS

In summary, tryptase is a new diagnostic marker of myeloid neoplasms and a useful test in clinical haematology.

Effects of platelet-derived growth factor isoforms on plasminogen activation by periodontal ligament and gingival fibroblasts

BACKGROUND AND OBJECTIVE

Platelet-derived growth factor isoforms and components of the plasminogen activator system are expressed at higher levels during periodontal regeneration. Recombinant platelet-derived growth factor-BB is approved for the treatment of periodontal defects. In the present study we investigated the effect of platelet-derived growth factor isoforms on the plasminogen activator system in periodontal fibroblasts.

MATERIAL AND METHODS

Human periodontal ligament fibroblasts and gingival fibroblasts were exposed to platelet-derived growth factor isoforms. Changes in urokinase-type plasminogen activator, tissue-type plasminogen activator, plasminogen activator inhibitor-1 and plasminogen activator inhibitor-2 transcript levels by platelet-derived growth factor-BB were monitored with a quantitative reverse transcription-polymerase chain reaction. Urokinase-type plasminogen activator and plasminogen activator inhibitor-1 protein levels were assessed by immunoassays. The effects of platelet-derived growth factor-BB on mitogen-activated protein kinase and phosphoinositol-3 kinase/Akt signaling were investigated by western blot and inhibitor studies. Casein zymography and kinetic assays revealed the size and activity, respectively, of the plasminogen activators.

RESULTS

We found that incubation of periodontal ligament fibroblasts and gingival fibroblasts with platelet-derived growth factor-BB resulted in enhanced levels of urokinase-type plasminogen activator and plasminogen activator inhibitor-1 transcripts, but not of tissue-type plasminogen activator and plasminogen activator inhibitor-2. Platelet-derived growth factor-BB also increased urokinase-type plasminogen activator and plasminogen activator inhibitor-1 release into the culture medium. Phosphorylation of extracellular signal-regulated kinase, p38, c-Jun N-terminal kinase and Akt was observed in fibroblasts of both origin. Inhibition of phosphoinositol-3 kinase signaling abrogated the platelet-derived growth factor-BB effect on plasminogen activator inhibitor-1 production. Casein zymography revealed enzymatic activity of the urokinase-type plasminogen activator in cell-conditioned media and lysates of periodontal ligament fibroblasts and gingival fibroblasts. Exposure of gingival fibroblasts, but not of periodontal ligament fibroblasts, to platelet-derived growth factor isoforms moderately increased total plasminogen activation in the medium.

CONCLUSION

These findings suggest that periodontal ligament fibroblasts attempt to maintain an equilibrium of the plasminogen activator system in the presence of platelet-derived growth factor isoforms.

Mixed-lineage eosinophil/basophil crisis in MDS: a rare form of progression

BACKGROUND

Basophilic crisis and eosinophilia are well recognized features of advanced chronic myeloid leukaemia. In other myeloid neoplasms, however, transformation with marked basophilia and eosinophilia is considered unusual.

DESIGN

We examined the long-term follow-up of 322 patients with de novo myelodysplastic syndromes (MDS) to define the frequency of basophilic, eosinophilic and mixed lineage (basophilic and eosinophilic) transformation.

RESULTS

Of all patients, only one developed mixed lineage crisis (>or= 20% basophils and >or= 20% eosinophils). In this patient, who initially suffered from chronic myelomonocytic leukaemia, basophils increased to 48% and eosinophils up to 31% at the time of progression. Mixed lineage crisis was not accompanied by an increase in blast cells or organomegaly. The presence of BCR/ABL and other relevant fusion gene products (FIP1L1/PDGFRA, AML1/ETO, PML/RAR alpha, CBF beta/MYH11) were excluded by PCR. Myelomastocytic transformation/myelomastocytic leukaemia and primary mast cell disease were excluded by histology, KIT mutation analysis, electron microscopy and immunophenotyping. Basophils were thus found to be CD123+, CD203c+, BB1+, KIT- cells, and to express a functional IgE-receptor. Among the other patients with MDS examined, 4(1.2%) were found to have marked basophilia (>or= 20%) and 7(2.1%) were found to have massive eosinophilia ( >or= 20%), whereas mixed-lineage crisis was detected in none of them.

CONCLUSIONS

Mixed basophil/eosinophil crisis may develop in patients with MDS but is an extremely rare event.

Clinical and prognostic significance of histamine monitoring in patients with CML during treatment with imatinib (STI571)

BACKGROUND

Although imatinib is highly effective in chronic myeloid leukemia (CML), drug-resistance may occur. Therefore, monitoring of minimal residual disease (MRD) during treatment with imatinib is important. However, most MRD-parameters are expensive and require special technology. We determined the value of histamine as MRD-marker in CML.

PATIENTS AND METHODS

Histamine levels were measured serially in whole blood samples before and during imatinib therapy in 80 CML patients by radioimmunoassay.

RESULTS

Histamine levels were highly upregulated in CML at diagnosis compared to healthy controls, and correlated with the presence of basophils. During treatment with imatinib, histamine levels decreased and returned to normal levels in those achieving a complete cytogenetic response (CCR). Loss of CCR during therapy was invariably accompanied by an increase in histamine. Moreover, a histamine level of >100 ng/ml three or six months after start of imatinib was associated with a significantly reduced probability of survival (p<0.05). Whereas basophils were found to correlate well with histamine during imatinib, no correlations were found between histamine and Ph+ metaphases or histamine and BCR/ABL.

CONCLUSION

Histamine-monitoring during treatment with imatinib is of prognostic significance.

Liposomal cytarabine for treatment of myeloid central nervous system relapse in chronic myeloid leukaemia occurring during imatinib therapy

BACKGROUND

Central nervous system (CNS) relapse in chronic myeloid leukaemia (CML) is rare and if recorded is usually found to occur in patients with lymphoblastic transformation. The BCR/ABL tyrosine kinase inhibitor imatinib is highly effective in patients with CML, but hardly crosses the blood-brain barrier.

PATIENTS AND METHODS

We report on two CML patients who developed a myeloid CNS relapse during treatment with imatinib. One patient was in major cytogenetic response at the time of CNS relapse. In both cases, the myeloid origin of neoplastic cells in the cerebrospinal fluid (CSF) was demonstrable by immunophenotyping, and their leukaemic origin by detection of the BCR/ABL oncoprotein. No BCR/ABL kinase domain mutations were found. Both patients received intrathecal liposomal cytarabine (50 mg each cycle; 6 cycles). In one patient, additional CNS radiation was performed, whereas in the other, consecutive treatment with dasatinib (70 mg per os twice daily) was started.

RESULTS

In response to therapy, the clinical symptoms resolved, and the leukaemic cells in the CSF disappeared in both cases. After three months of observation, both patients are in complete cytogenetic and major molecular response, without evidence for a systemic or a CNS relapse.

CONCLUSIONS

'Anatomic' resistance against imatinib in the CNS can lead to a myeloid CNS relapse. Liposomal cytarabine with or without radiation is effective as local therapy in these patients. For systemic treatment and prophylaxis, BCR/ABL kinase inhibitors crossing the blood-brain barrier such as dasatinib should be considered in patients with CNS relapse.

In vivo effects of imatinib mesylate on human haematopoietic progenitor cells

BACKGROUND

Imatinib mesylate has considerable antineoplastic activity in patients with chronic myeloid leukaemia (CML) and some solid tumours. Although originally regarded as nontoxic for normal haematopoiesis, mild to moderate myelosuppression is a commonly observed side-effect of this treatment. Recently, this molecule has been shown to suppress normal haematopoietic progenitor cells in vitro. This is the first study that has investigated the effect of imatinib on haematopoietic progenitor cells in vivo.

MATERIALS AND METHODS

We investigated the number of circulating haematopoietic progenitor cells in 79 patients with CML and five patients with solid tumours who were treated with imatinib for at least 3 months. Bone marrow progenitor cells were assessed in a subgroup of 18 patients with CML after 12 months of imatinib treatment. Results were compared with haematopoietic progenitor cell numbers of normal controls.

RESULTS

Circulating progenitors of all classes were significantly decreased in CML up to 24 months of imatinib therapy compared with healthy controls (median progenitor cells in CML after 12 months: CFU-GM 62, range 0-2543; BFU-E 216, range 0-3259; CFU-GEMM 0, range 0-139; versus controls: CFU-GM 208, range 50-936; BFU-E 690, range 120-1862; CFU-GEMM 20, range 4-77; P < 0.001). Similar reductions in the number of progenitor cells derived from bone marrow were found in a subgroup of 18 patients with CML. In patients with solid tumours the number of circulating progenitor cells was significantly lower under treatment with imatinib when compared with the controls. Withdrawal of imatinib in a patient with a malignant brain tumour resulted in a prompt normalization of circulating progenitors.

CONCLUSIONS

This study suggests that imatinib exerts myelosuppressive effects through inhibition of haematopoietic progenitor cells.

The tryptase positive compact round cell infiltrate of the bone marrow (TROCI-BM): a novel histopathological finding requiring the application of lineage specific markers

AIMS

Compact tryptase-positive round cell infiltrates of the bone marrow (TROCI-BM) are very rare histopathological findings and may pose challenging problems with regard to the cell type involved (either mast cells or basophilic granulocytes) and the exact diagnosis.

METHODS

A selected panel of immunohistochemical markers against mast cell and basophil related antigens, including CD25, CD34, CD117/Kit, and the 2D7 antigen (which is found only in basophilic granulocytes) on a total of 410 routinely processed bone marrow biopsy specimens (including 88 cases of systemic mastocytosis (SM), 20 cases of chronic myeloid leukaemia (CML), 92 cases of myeloid neoplasms other than CML, and 210 controls with normal/reactive bone marrows).

RESULTS

In total, 17 cases with TROCI-BM could be identified: 11 SM (including two cases of well-differentiated SM and two mast cell leukaemias; MCL), 2 myelomastocytic leukaemia (MML), 2 CML with excess of basophils (secondary basophilic leukaemia (CMLba)), and 2 tryptase positive acute myeloid leukaemia (AML). Regarding the cell types involved, TROCI-BM cells were found to express CD117/Kit in all cases of SM and MCL. In MML and tryptase postitive AML, TROCI-BM cells were found to coexpress CD34 and Kit. The basophil specific antigen 2D7 was only detected in CD34/Kit negative TROCI-BM cells in two patients with CMLba. The activating point mutation D816V was detected in 8/11 patients with SM but not in any of the other haematological malignancies.

CONCLUSIONS

In summary, a total of six rare myeloid neoplasms may present with a novel immunohistochemical phenomenon tentatively termed TROCI-BM.

Enumeration and immunohistochemical characterisation of bone marrow basophils in myeloproliferative disorders using the basophil specific monoclonal antibody 2D7

BACKGROUND

Basophils are highly specialised granulocytes that express a unique profile of antigens and increase in myeloproliferative disorders (MPD). In chronic myeloid leukaemia (CML), basophilia is a diagnostic and prognostic determinant. So far, however, no reliable approach for routine detection and enumeration of bone marrow basophils has become available.

OBJECTIVE

To detect and enumerate basophils in bone marrow sections in patients with CML and other MPD.

METHODS

The anti-basophil antibody 2D7 was applied to paraffin embedded bone marrow sections from normal/reactive subjects (n = 31), patients with CML (chronic phase, n = 37; accelerated phase, n = 9), and other MPD (chronic idiopathic myelofibrosis (CIMF), n = 20; polycythaemia vera (PV), n = 20; essential thrombocythaemia (ET), n = 20; indolent systemic mastocytosis (ISM), n = 7).

RESULTS

As assessed by serial section staining, 2D7(+) cells were found to co-express myeloperoxidase, histidine decarboxylase, CD9, and CD43, but did not express B cell or T cell restricted antigens. 2D7(+) bone marrow cells were found to increase in CML compared with normal/reactive bone marrow and other MPD (median numbers of 2D7(+) cells/mm(2): CML, 33; normal/reactive bone marrow, 6; CIMF, 10; PV, 6; ET, 5; ISM, 3; p<0.05). The highest basophil counts were recorded in accelerated phase CML (115/mm(2)).

CONCLUSIONS

A novel immunohistochemical procedure has been established for basophil detection in normal bone marrow and MPD. This approach should help in the quantification of bone marrow basophils at diagnosis and during anti-leukaemic treatment.

Detection of differentiation- and activation-linked cell surface antigens on cultured mast cell progenitors

BACKGROUND

Mast cells (MC) are multifunctional effector cells of the immune system. They derive from uncommitted CD34(+) hemopoietic progenitor cells (HPC). Depending on the stage of maturation and the environment, MC variably express differentiation- and activation-linked antigens. Little is known, however, about the regulation of expression of such antigens in immature human MC.

METHODS

We analyzed expression of CD antigens on human MC grown from cord blood-derived CD34(+) HPC. The HPC were isolated by magnetic cell sorting (MACS) and FACS to >97% purity, and were cultured in stem cell factor (SCF) and interleukin (IL)-6 with or without additional cytokines (IL-4 or IL-10) in serum-free medium. The cell surface phenotype of MC was determined by monoclonal antibodies and flow cytometry.

RESULTS

Cultured MC progenitors were found to react with antibodies against various CD antigens including CD58, CD63, CD117, CD147, CD151, CD203c, and CD172a, independent of the growth factors used and time-point investigated (days 14-42). CD116 [granulocyte-macrophage colony-stimulating factor receptor alpha (GM-CSFRalpha)] and CD123 (IL-3Ralpha) were expressed on MC precursors on day 14, but disappeared thereafter. Cultured MC did not express CD2, CD3, CD5, CD10, CD19, or CD25. Addition of IL-10 to MC cultures showed no effect on expression of CD antigens. However, IL-4 was found to promote expression of CD35 and CD88 on cultured MC without changing expression of other CD antigens.

CONCLUSIONS

Most MC antigens may already be expressed at an early stage of mastopoiesis. Whereas IL-3R and GM-CSFRs are lost during differentiation of MC, these cells may acquire complement receptors (CD35, CD88) under the influence of distinct cytokines.

A comparative study on demographic, hematological, and cytogenetic findings and prognosis in acute myeloid leukemia with and without leukemia cutis

We studied the incidence of leukemia cutis (LC) in 381 consecutive patients with acute myeloid leukemia (AML) in a single institution and compared the demographic, hematological, and cytogenetic findings in AML patients with and without LC. We also examined the response to intensive chemotherapy, overall survival, and duration of remission in this patient population with regard to the presence of LC. The prevalence of LC was 3.7% in clinically diagnosed patients and 2.9% in biopsy-proven cases, respectively. Patients with and without LC did not differ with regard to age, sex, white blood cell counts, hemoglobin, fibrinogen, and platelet counts at diagnosis, but lactate dehydrogenase (LDH) was significantly higher in patients with LC. Various karyotype abnormalities were found, but in patients with LC numerical abnormalities of chromosome 8 were significantly more common ( P<0.0001). Patients with LC did not differ from patients without LC with regard to remission rate, but there was a trend towards shorter remission duration in patients with LC. We conclude that patients with LC have some features different from patients without this symptom. The increased frequency of numerical aberrations of chromosome 8 in patients with LC was the most interesting observation of our study. The pathophysiological significance of this finding remains to be determined.

Expression, epitope analysis, and functional role of the LFA-2 antigen detectable on neoplastic mast cells

Recent data suggest that mast cells (MCs) in patients with systemic mastocytosis or mast cell leukemia express a CD2-reactive antigen. To explore the biochemical nature and function of this antigen, primary MCs as well as the MC line HMC-1 derived from a patient with mast cell leukemia were examined. Northern blot experiments revealed expression of CD2 messenger RNA in HMC-1, whereas primary nonneoplastic MCs did not express transcripts for CD2. In cell surface staining experiments, bone marrow (BM) MCs in systemic mastocytosis (n = 12) as well as HMC-1 cells (30%-80%) were found to express the T11-1 and T11-2 (but not T11-3) epitopes of CD2. By contrast, BM MCs in myelodysplastic syndromes and nonhematologic disorders (bronchiogenic carcinoma, foreskin phimosis, uterine myeomata ) were consistently CD2(-). All MC species analyzed including HMC-1 were found to express LFA-3 (CD58), the natural ligand of CD2. To study the functional role of CD2 on neoplastic MCs, CD2(+) and CD2(-) HMC-1 cells were separated by cell sorting. CD2(+) HMC-1 cells were found to form spontaneous aggregates and rosettes with sheep erythrocytes in excess over CD2(-) cells, and a T11-1 antibody inhibited both the aggregation and rosette formation. Moreover, exposure of CD2(+) HMC-1 cells to T11-1 or T11-2 antibody was followed by expression of T11-3. In addition, stimulation of neoplastic MCs through T11-3 and a second CD2 epitope resulted in histamine release. These data show that neoplastic MCs express functionally active CD2. It is hypothesized that expression of CD2 is associated with pathologic accumulation and function of MCs in systemic mastocytosis.

Detection of tryptase in cytoplasmic granules of basophils in patients with chronic myeloid leukemia and other myeloid neoplasms

Tryptases are serine proteases primarily expressed in mast cells. Normal blood basophils express only trace amounts of the enzyme. However, recent immunohistochemical studies have raised the possibility that neoplastic basophils express significant amounts of tryptase. In this study, tryptase expression was analyzed in normal and neoplastic basophils by immunoelectron microscopy using antitryptase monoclonal antibody G3. Basophils were obtained from patients with chronic myeloid leukemia (CML), idiopathic myelofibrosis (IMF), and myelodysplastic syndrome (MDS), and from healthy donors. Tryptase-immunoreactive material was detected in cytoplasmic granules of basophils in CML, IMF, and MDS. By contrast, normal basophils did not contain significant amounts of tryptase by immunoelectron microscopy. As assessed by reverse transcription-polymerase chain reaction, neoplastic basophils contained messenger RNA (mRNA) for alpha-tryptase, but no beta-tryptase mRNA. In summary, these data provide evidence that neoplastic basophils in CML, IMF, and MDS can express detectable amounts of tryptase. Therefore, tryptase should not be regarded as specific for mast cells when neoplastic myeloid cells are analyzed.

Variable expression of activation-linked surface antigens on human mast cells in health and disease

Mast cells (MC) are multipotent effector cells of the immune system. They contain an array of biologically active mediator substances in their granules. MC also express a number of functionally important cell surface antigens, including stem cell factor receptor (SCFR=kit=CD117), high affinity IgER (FcepsilonRI), or CSaR (CD88). Respective ligands can induce or promote degranulation, migration, or cytokine production. Other integral surface molecules can mediate adhesion or cell aggregation. Recent data suggest that a number of critical molecules are variably expressed on the surface of human MC. In fact, depending on the environment (organ), stage of cell maturation, type of disease, and other factors, MC express variable amounts of activation-linked antigens (CD25, CD63, CD69, CD88), cell recognition molecules (CD2, CD11, CD18, CD50, CD54), or cytokine receptors. At present, however, little is known about the mechanisms and regulation of expression of such antigens. The present article gives an overview of MC phenotypes in health and disease, and attempts to provide explanations for the phenotypic variability of MC.

Expression of homing receptors and related molecules on human mast cells and basophils: a comparative analysis using multi-color flow cytometry and toluidine blue/immunofluorescence staining techniques

Mast cells (MC) and blood basophils (Ba) are multifunctional effector cells of the immune system and accumulate in areas of ongoing disease. However, despite of similar morphology, MC and Ba differ from each other in terms of cell surface receptor expression, mediator content, and tissue distribution. In order to gain new insights into mechanisms and molecules responsible for the distribution and accumulation of MC and Ba, we have investigated expression of homing receptors on primary human MC (lung, n=28; uterus, n=17), Ba (healthy donors, n=64), the mast cell line HMC-1, and the basophil line KU-812. Expression of cell surface antigens on MC and Ba was analyzed by mAb and indirect immunofluorescence staining techniques. In addition to previous findings, Ba were found to react with mAb against the selectin-ligands sLe(x) (CD15s) and PSGL-1 (CD162), L-selectin (CD62L), beta7-integrin, the 'matrix-receptor' neurothelin (CD147), platelet-endothelial cell tetraspan antigen-3 (PETA-3=CD151), and BST-1 (CD157). Novel antigens detectable on MC (lung and uterus) were CD147, CD151, CD157 and CD49c (VLA-3alpha). By contrast, MC were not recognized by mAb to sLe(x), PSGL-1, L-selectin, or beta7 integrin. No reactivity of Ba or MC with mAb to syndecan-1 (CD138), VE-cadherin (CD144), MUC18/MCAM (CD146), MGC-24 (CD164), or ALCAM (CD166) was found. The cell lines HMC-1 and KU-812 expressed a similar profile of antigens when compared to primary cells. In summary, Ba and MC express a unique profile of homing molecules. Apparently, Ba differ from MC in expression of recognition receptors relevant for binding to endothelium and consecutive transmigration.

Successful treatment with arsenic trioxide of a patient with ATRA-resistant relapse of acute promyelocytic leukemia

Arsenic trioxide has recently been introduced as a promising new agent to treat refractory acute promyelocytic leukemia (APL). In the present study, arsenic trioxide was given intravenously for 42 days to a 56-year-old female patient suffering from chemotherapy/ATRA-resistant APL, with 43% APL blasts in the bone marrow and elevated D-dimers. During the first days of arsenic trioxide treatment a rapid decrease in the D-dimers was seen (normal values reached until day 7), together with a slight decrease in peripheral blood leukocytes. This initial coagulation response was followed by a second phase of hematological response (starting on days 15-20) characterized by leukocytosis, occurrence of myeloid progenitor cells in the peripheral blood, and a decrease in bone marrow blasts (<1% on days 28 and 36). Finally, the patient entered complete hematological and cytogenetic remission, although the PML-RAR alpha fusion product was still detectable by PCR. These data confirm the therapeutic value of arsenic trioxide in relapsed/resistant APL.

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.

Inhibition of allergen-induced histamine release from human basophils by cyclosporine A and FK-506

A number of structurally different allergens trigger the release of mediators from basophils by cross-linking of IgE receptors. In this study, we analyzed the effects of cyclosporine A (CSA) and FK-506 on allergen-induced histamine release in human blood basophils obtained from birch- or grass-pollen-allergic donors (n = 12). Preincubation of basophils with CSA (0.003-3 microg/ml) or FK-506 (0.003-3 microg/ml) led to inhibition of histamine release induced by purified recombinant tree pollen allergens (r Bet v 1, r Bet v 2) and timothy grass pollen allergens (r Ph1 p 1, r Ph1 p 2, r Ph1 p 5). The effects of CSA and FK-506 were dose dependent, with IC50 values ranging between 0.03 and 0.3 microg/ml for both CSA and FK-506. Cyclosporine H, an inactive CSA analog, did not show any effect on allergen-induced histamine secretion. IgE dependency of the reaction was demonstrated in passive transfer experiments using highly enriched human basophils (> 95% pure) and specific IgE from a patient allergic to Bet v 2. In summary, our data show that CSA and FK-506 inhibit recombinant-allergen-induced histamine release from peripheral blood basophils in allergic donors.

Inhalation scintigraphy with iodine-123-labeled interferon gamma-1b: pulmonary deposition and dose escalation study in healthy volunteers

Recent studies have suggested that recombinant interferon gamma (IFNg) may be useful in the treatment of various respiratory diseases, such as chronic inflammatory disease. This study was undertaken to investigate the dose response of escalating doses of inhaled 123I-labeled IFNg (123I-IFNg) and its safety, biodistribution and radiation absorbed doses in healthy volunteers.

METHODS

IFNg was labeled with 123I to produce a specific activity of 1800 MBq/mg of IFNg. The biological activities of 123I-IFNg, nebulized 123I-IFNg and unlabeled IFNg were evaluated in various functional in vitro tests. Ten healthy volunteers were enrolled in the in vivo dose escalation study (180 MBq of 123I-IFNg diluted with 0.1-2 mg of INFg). Inhalation scintigraphy, using a Pari-Master nebulizer, was performed for up to 37 min, during which dynamic posterior images of the lungs were obtained. Whole-body scanning was performed at various time points up to 24 hr postinjection, for biodistribution and dosimetry purposes. Blood, urine and feces were also collected over this 24-hr period. Lung perfusion scintigraphy with 99mTc-microspheres was performed at the end of the study for attenuation correction.

RESULTS

Inhaled nebulized IFNg showed a uniform deposition pattern in the lungs with deposition ratios of 0.74 (central-to-peripheral) and 0.78 (upper-to-lower). The lung deposition of IFNg was time-dependent, with a deposition half-time between 1 and 5 min. Despite a large interindividual variation, the total lung deposition was proportional to the nebulizer charge and was 53 +/- 12% of the inhaled dose and 19 +/- 7% of the initial nebulizer charge (between 0.1 and 2 mg of IFNg). The biological half-life in the lung could be fitted to a biexponential function, with resultant half-lives of 1 and 11 hr. Blood activity was maximal at 3.5 hr after inhalation and was due to free iodine. The radioactivity was excreted through both the urinary and intestinal tracts. Plasma IFNg levels did not significantly increase over time, and no significant HLA-DR induction on peripheral blood cells was detected. The highest radiation absorbed doses of 0.14 and 0.19 mGy/MBq were determined for the trachea and the lower intestines, respectively. The effective dose equivalent was 0.05 mSv/MBq.

CONCLUSION

After inhalation with the Pari-Master nebulizer, IFNg deposits normally in the lungs and shows no systemic effects in healthy volunteers.

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.

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.

Tumor necrosis factor-alpha induction of major histocompatibility complex class II antigen expression is inhibited by interferon-gamma in a monocytic cell line

Regulation of major histocompatibility complex (MHC) class II antigen expression by cytokines has been suggested to play a major role in the initiation and propagation of immune and autoimmune processes. The analysis of class II gene regulation benefits greatly from the existence of mutants with defects in regulatory factors. We report the establishment of a subclone of the human monocytic cell line U937, termed C119/9, with unusual cytokine regulation of MHC class II expression. In contrast to the parental U937 cell line, only tumor necrosis factor (TNF)-alpha, and not interferon (IFN)-gamma induces the expression of MHC class II antigens on C119/9 cells, and paradoxically, this induction was inhibited almost completely by IFN-gamma. The HLA-DR induction is controlled at the transcriptional level by the first 150 bp of the class II promoter which contains all the class II consensus elements. Both HLA-DR and -DQ mRNA are induced by TNF-alpha treatment, and both are diminished upon co-treatment with TNF-alpha and IFN-gamma. This antagonism between TNF-alpha and IFN-gamma seem to be restricted to MHC class II genes. This subline of U937 cells may be useful in further studies of MHC class II regulation.

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.

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.

Differential response of human basophils and mast cells to recombinant chemokines

Chemokines are proinflammatory peptides regulating the functions of various hematopoietic cells. We have analyzed the effects of seven recombinant human (rh) chemokines (MCAF, RANTES, MIP-1 alpha, MIP-1 beta, IL-8, GRO, and IP-10) on the growth and function of human basophils and mast cells. We found that MCAF, but not RANTES, MIP-1 alpha, MIP-1 beta, IL-8, GRO, or IP-10, causes direct and dose-dependent histamine release from basophils (MCAF, 5 micrograms/ml: 26.9 +/- 3.4%; other chemokines: < 5% of total histamine). An increased (2.1 to 3.5-fold) response to MCAF was obtained when basophils were preincubated with rh interleukin-3 (100 units/ml). Moreover, IL-3-primed basophils became responsive to physiologic concentrations (< 1 microgram/ml) of MCAF, IL-8, and RANTES. None of the chemokines tested was able to induce histamine secretion in mast cells obtained from lung (n = 2), skin (n = 1), uterus (n = 3), or tonsils (n = 3), even when cells had been preincubated with the mast cell agonist SCF. The chemokines also failed to modulate the expression of activation antigens (CD11b/C3biR, CD25/IL-2R beta, CD63, IL-3R alpha, CD117/c-kit) on the mast cell line HMC-1 or the basophil cell line KU-812 and were unable to induce differentiation of basophils or mast cells in culture. Together, our results show that basophils respond to rhIL-8, rhMCAF, and rhRANTES and that, unlike human basophils, human mast cells are unresponsive to recombinant chemokines.

Activated naive CD4+ peripheral blood T cells in autoimmune thyroid disease

To better understand the clinical significance of changes in lymphocytes in thyroid disease this study analyzed the proportion of CD19+, CD3+, CD4+ and CD8+ cells among circulating lymphocytes in Graves' disease (GD, n = 34) and autoimmune hypothyroidism (AH, n = 28) vs healthy subjects (n = 15). In addition, the expression of CD25 and CD45 isoforms on CD4+ T cells as well as their modulation by methimazole in patients with GD was measured using three color flow cytometry. It was observed that, irrespective of age, both patients with GD (17.6 +/- 7.0% +/- SD) and those with AH (19.0 +/- 9.5%) had an increased percentage of the CD25+CD45RA+ (naive) subpopulation of helper cells vs healthy subjects (7.9 +/- 2.3%, p < 0.0001). In patients with AH peripheral memory cells and hence overall CD25+ cells were more frequent among helper cells (56.7 +/- 12.2%) than in healthy subjects (40.8 +/- 14.0%, p < 0.001). Patients with GD (46.2 +/- 13.4%) did not differ from normal subjects in this respect. Treatment of GD with MMI reduced the percentage of CD25+CD45RA+ cells among CD4+ cells toward values seen in healthy subjects. In addition, we confirm previous reports that CD8+ cells toward values seen in healthy subjects. In addition, we confirm previous reports that CD8+ cells are significantly reduced in AH (23.9 +/- 4.9%) and untreated Graves' disease (23.2 +/- 6.6%) vs healthy subjects (32.2 +/- 5.9%, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)