Gerit-Holger Schernthaner

Utility of flow cytometric analysis of mast cells in the diagnosis and classification of adult mastocytosis

The diagnosis of bone marrow (BM) involvement in mastocytosis has mainly been based on conventional histology. Nevertheless, in recent years, three major methodological advances have been made: the measurement of serum tryptase levels, the immunohistochemical assessment of mast cell (MC) tryptase, and the immunophenotypical characterization of BMMC using flow cytometry (FCM). The most characteristic immunophenotypic feature in mastocytosis is the coexpression of CD2 and CD25 antigens, which are never present in normal BMMC and constitute a phenotypic hallmark of BMMC in adult mastocytosis. Such observations would support the need to include the immunophenotypic analysis of MC in the diagnosis of mastocytosis.

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

Summary: 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 (FcεRI), or C5aR (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.

Correlation of different circulating endothelial progenitor cells to stages of diabetic retinopathy: first in vivo data.

PURPOSE To investigate vasculogenic circulating progenitor cells (CPCs), endothelial progenitor cells (EPCs), and mature EPCs in patients with type 1 diabetes mellitus (T1DM) with or without diabetic retinopathy (DR). METHODS A case-control study comparing 90 patients with T1DM with and without DR was performed. Patients were studied and staged for retinopathy according to the Early Treatment of Diabetic Retinopathy Study (ETDRS) classification. Ninety patients were included: 30 without DR (control [CO]), 30 with mild nonproliferative DR (mNPDR), 10 with moderate-severe NPDR (msNPDR), 10 with mild-moderate proliferative diabetic retinopathy (mmPDR), and 10 with high-risk PDR (hrPDR). CPCs (CD34/CD133), EPCs (CD34/CD133/CD309), and mature EPCs (CD34/CD133/CD309/CD31) were enumerated by flow cytometry. RESULTS EPCs were reduced in mNPDR (114 +/- 66; P < 0.001) and msNPDR (77 +/- 40; P = 0.042) compared with CO (244 +/- 115). In contrast, EPCs were unchanged in mmPDR (248 +/- 155) compared with CO. Strikingly, EPCs were augmented in hrPDR (389 +/- 124) compared with all other stages. Numbers of undifferentiated progenitor cells (CPCs) did not differ among CO, mmPDR, and hrPDR. Augmentation (3x) of mature EPCs in hrPDR (325 +/- 118; P < 0.001) compared with CO (100 +/- 49) but against all other stages of DR was observed. The percentage of mature EPCs/EPCs was augmented in an ETDRS classification-dependent manner. CONCLUSIONS In patients with T1DM with DR, EPCs undergo stage-related regulation. In nonproliferative retinopathy, a reduction of EPCs was observed, and in proliferative retinopathy, a dramatic increase of mature EPCs was observed.

Detection of novel CD antigens on the surface of human mast cells and basophils.

Background: Mast cells (MC) and basophils are effector cells of allergic reactions. Growth and function of these cells are regulated by a network of cytokines, other ligands, and respective cell surface membrane receptors. Methods: In the present study, we examined the expression of novel CD antigens on human lung MC, skin MC, blood basophils, the MC line HMC-1, and the basophil cell line KU-812. Expression of surface antigens was analyzed by monoclonal antibodies (mAbs) and indirect immunofluorescence staining techniques. Results: Primary MC were found to react with mAbs against KIT (CD117), the signal regulatory protein SIRP-α (CD172a), and the ectoenzyme E-NPP3 (CD203c). Human basophils were found to express large amounts of E-NPP3 and lower levels of Siglec-5 (CD170), CXCR4 (CD184) and SIRP-α. The HMC-1 cell line was recognized by mAbs against SIRP-α, CXCR4, endothelial protein C receptor (CD201) and E-NPP3. KU-812 cells were found to react with mAbs against E-NPP3, CXCR4 and glycophorin C (CD236R), but did not react with mAb against endothelial protein C receptor. Most of the other CD antigens tested disclosed negative results. Conclusions: In summary, our data provide further evidence that MC and basophils express a unique composition of surface antigens. The use of novel CD antibodies may help to isolate MC and basophils and to study their functional properties.

Fetuin-A levels are increased in patients with type 2 diabetes and peripheral arterial disease

OBJECTIVE Low levels of fetuin-A, a systemic calcification inhibitor, are linked to mortality in patients on dialysis. In contrast, elevated fetuin-A is associated with cardiovascular events in non-renal patients. We investigated fetuin-A in patients with type 2 diabetes and peripheral arterial disease (PAD). RESEARCH DESIGN AND METHODS We studied fetuin-A in 76 patients with PAD and normal glucose metabolism (NGM-PAD) and in 129 patients with PAD and type 2 diabetes (type 2 diabetes–PAD). Additionally, 40 patients with diabetes without any complications (type 2 diabetes–non-PAD) were examined. RESULTS Type 2 diabetes–PAD subjects (399 ± 155 μg/ml) had significantly higher fetuin-A levels than type 2 diabetes–non-PAD subjects (247 ± 42; P < 0.001). In NGM-PAD subjects (376 ± 144), fetuin-A was significantly higher than in type 2 diabetes–non-PAD subjects (P < 0.001). Type 2 diabetes–PAD patients with mediasclerosis had lower fetuin-A than subjects without (P < 0.03). Regression analysis in type 2 diabetes–PAD subjects revealed that glycated A1C (P < 0.001) and mediasclerosis (P = 0.004) were the strongest predictors of fetuin-A. Multivariate regression revealed that a 1-SD increase in fetuin-A was associated with an odds ratio (OR) of 2.1 (95% CI 1.1–3.3; P < 0.001) for the prevalence of PAD and an OR of 1.4 (1.0–1.7, P = 0.039) for the prevalence of myocardial infarction. CONCLUSIONS In contrast to previous findings, fetuin-A was higher in type 2 diabetes–PAD patients than in type 2 diabetes–non-PAD patients. In NGM-PAD patients, fetuin-A was also higher than in type 2 diabetes–non-PAD patients. In type 2 diabetes–PAD patients, fetuin-A was inversely associated with mediasclerosis—the calcification process pathognomonic for diabetic PAD. This association persisted in multivariate regression, which is in line with the calcification inhibition in coronary heart or renal disease.

Overexpression of complement receptors and related antigens on the surface of bone marrow mast cells in patients with systemic mastocytosis

Summary. Depending on their stage of maturation and other factors, mast cell (MC) subsets differ from each other in terms of the expression of complement‐associated antigens. This study analysed the expression of various complement‐related cell surface antigens (CD11b/CR3, CD11c/CR4, CD35/CR1, CD55/DAF, CD59/MIRL, CD88/C5aR) on bone marrow mast cells (BMMC) in patients suffering from systemic mastocytosis (SM), other haematological diseases and non‐haematological disorders (control groups). Expression of complement‐associated cell surface antigens was analysed by flow cytometry. There were clear immunophenotypic differences between BMMC obtained from patients with SM and those from the control subjects: the percentage of patients expressing surface CD11c, CD35 and CD88 was significantly higher in patients with SM (76%, 100%, 54%) than in the control subjects (58%, 11%, 18%) (P < 0·05). In addition, the levels of CD11c, CD35 and CD88 expressed per MC (sites per cell) were significantly higher (P < 0·05) in SM than in the control group. Expression of the complement regulatory molecules CD55 and CD59 was detected in BMMC in all patients analysed. However, the levels of CD59 per BMMC were higher in patients with SM as compared with the control subjects, which could help to explain the formation of BMMC aggregates in the former group of individuals. Together, our results showed that BMMC in systemic mastocytosis overexpressed the cell surface membrane receptors involved in binding of complement components and complement‐mediated cell activation. Whether this pathological expression of complement receptors is of pathophysiological significance remains to be determined.

Activation of human mast cells through stem cell factor receptor (KIT) is associated with expression of bcl-2

Background: Mast cells (MCs) are multifunctional effector cells of the immune system. These cells originate from pluripotent hemopoietic progenitors. In contrast to basophils and other leukocytes, MCs exhibit a remarkably long life span (years) in vivo. Although a role for stem cell factor (SCF) and SCF receptor (KIT) in long-term survival of MCs has been proposed, the underlying biochemical mechanisms remain unknown. Materials and Methods:We have examined expression of ‘survival-related’ molecules of the bcl-2 family including bcl-2 and bcl-xL, in primary human MCs and the human MC line HMC-1. Primary MCs were isolated from dispersed lung tissue by cell sorting using an antibody against KIT. mRNA expression was analyzed by RT-PCR and Northern blotting. Results: As assessed by RT-PCR, purified unstimulated lung MCs (>98% pure) exhibited KIT- and bcl-xL mRNA, but did not express bcl-2 mRNA. However, exposure of lung MCS to SCF (100 ng/ml) for 8 h resulted in expression of bcl-2 mRNA. Corresponding results were obtained by immunocytochemistry. In fact, exposure of MC to SCF resulted in expression of the bcl-2 protein whereas unstimulated MCs displayed only the bcl-xL protein without expressing the bcl-2 protein. The human MC leukemia cell line HMC-1, which contains a mutated and intrinsically activated SCF receptor, showed constitutive expression of both bcl-2 and bcl-xL at the mRNA and protein level. Conclusion: Our data show that human MCs can express members of the bcl-2 family. It is hypothesized that bcl-xL plays a role in KIT-independent growth of MCs, whereas bcl-2 may be involved in KIT-dependent functions of MCs.

Cerivastatin and atorvastatin inhibit IL-3-dependent differentiation and IgE-mediated histamine release in human basophils and downmodulate expression of the basophil-activation antigen CD203c/E-NPP3.

Recent data suggest that the statins, apart from their lipid‐lowering activity, exhibit profound anti‐inflammatory effects. Basophils are major proinflammatory effector cells in diverse pathologic reactions. We have examined the in vitro effects of five different statins on primary human basophils, their progenitors, and the basophil cell line KU‐812. Preincubation of blood basophils with cerivastatin or atorvastatin (0.1–100 μM) for 24 h reduced their capacity to release histamine on immunoglobulin E (IgE)‐dependent stimulation in a dose‐dependent manner. These statins also inhibited IgE‐dependent up‐regulation of the basophil‐activation antigen CD203c. Moreover, both statins suppressed interleukin‐3‐induced differentiation of basophils from their progenitors as well as 3H‐thymidine uptake in KU‐812 cells. All inhibitory effects of cerivastatin and atorvastatin were reversed by mevalonic acid (200 μM). The other statins tested (lovastatin, simvastatin, pravastatin) did not show significant inhibitory effects on basophils. Together, these data identify cerivastatin and atorvastatin as novel inhibitors of growth and activation of human basophils.

A case of smouldering mastocytosis with peripheral blood eosinophilia and lymphadenopathy

Systemic mastocytosis (SM) is a clonal hematologic disease showing abnormal growth and accumulation of mast cells (MC) in visceral organs with or without skin involvement. The clinical course in SM is variable. In fact, indolent and aggressive variants have been described. In addition, SM patients may acquire an associated hematologic clonal non-MC lineage disease (AHNMD). In some cases, hematologic parameters are indicative of slowly progressing SM although the clinical course remains indolent over years. These cases have been referred to as smouldering SM. We report on a smouldering patient presenting with typical skin lesions, hypercellular marrow with focal MC aggregates, persistent leukocytosis (20,000-30,000/microl) with eosinophilia (5-10%), marked lymphadenopathy, and splenomegaly. The C-KIT mutation Asp-816-Val confirmed the diagnosis of SM. The clinical picture remained stable during an observation period of 10 years without signs of progression to an AHNMD or a high grade MC disease. These data show that some patients with SM can remain in a clinically indolent smouldering state over years even when presenting with marked eosinophilia and lymphadenopathy.

Circulating Angiopoietic Cells and Diabetic Retinopathy in Type 2 Diabetes Mellitus, with or without Macrovascular Disease

PURPOSE To investigate different types of circulating angiopoietic cells, such as vasculogenic circulating progenitor cells (CPCs), endothelial progenitor cells (EPCs), and mature EPCs (matEPCs) in patients with type 2 diabetes mellitus (T2DM), with or without diabetic retinopathy (DR) and with or without macrovascular disease (MVD). METHODS One hundred twenty-six patients with T2DM-66 with MVD and 60 without MVD-were enrolled in a case-control study. MVD comprised coronary heart disease, peripheral arterial disease, stroke, or various combinations of those conditions. By a modified Early Treatment of Diabetic Retinopathy Study (ETDRS) classification, 55 patients were classified without DR (CO), 19 with mild nonproliferative DR (mNPDR), 16 with moderate-severe NPDR (msNPDR), 19 with early proliferative diabetic retinopathy (ePDR), and 17 with high-risk PDR (hrPDR). CPCs (CD34/CD133), EPCs (CD34/CD133/CD30), and matEPCs (CD34/CD133/CD309/CD31) were enumerated by flow cytometry. RESULTS Patients with MVD CPCs, EPCs, and matEPCs showed a significant, stepwise decline with advancing stages of retinopathy. In contrast, in the patients without MVD, EPCs and matEPCs reached up to 56% of CPCs and 37% of EPCs. On the other hand, the percentage of EPCs and matEPCs was reduced to 5% of CPCs and EPCs each in MVD patients. Thus, the percentage of EPCs and matEPCs in comparison with that of CPCs and EPCs represented an 11- and 7-fold difference. CONCLUSIONS The circulating angiopoietic CPCs, EPCs, and matEPCs in T2DM patients with DR had a different regulations, with increasing relative differences occurring in proliferative DR, apparently depending on the macrovascular comorbidities. Patients with MVD showed a strong retinopathy-stage-dependent depletion of all angiopoietic cells.