Proteomics and metabolomics identify molecular mechanisms of aging potentially predisposing for chronic lymphocytic leukemia

B cell chronic lymphocytic leukemia (B-CLL), the most common type of leukemia in adults, is still essentially incurable despite the development of novel therapeutic strategies. This reflects the incomplete understanding of the pathophysiology of this disease. A comprehensive proteome analysis of primary human B-CLL cells and B cells from younger as well as elderly healthy donors was performed. For comparison, the chronic B cell leukemia cell line JVM-13 was also included. A principal component analysis comprising 6,945 proteins separated these four groups, placing B cells of aged-matched controls between those of young donors and B-CLL patients, while identifying JVM-13 as poorly related cells. Mass spectrometric proteomics data have been made fully accessible via ProteomeXchange with identifier PXD006570-PXD006572, PXD006576, PXD006578, and PXD006589-PXD006591. Remarkably, B cells from aged controls displayed significant regulation of proteins related to stress management in mitochondria and ROS stress such as DLAT, FIS1, and NDUFAB1, and DNA repair, including RAD9A, MGMT, and XPA. ROS levels were indeed found significantly increased in B cells but not in T cells or monocytes from aged individuals. These alterations may be relevant for tumorigenesis and were observed similarly in B-CLL cells. In B-CLL cells, some remarkable unique features like the loss of tumor suppressor molecules PNN and JARID2, the stress-related serotonin transporter SLC6A4, and high expression of ZNF207, CCDC88A, PIGR and ID3, otherwise associated with stem cell phenotype, were determined. Alterations of metabolic enzymes were another outstanding feature in comparison to normal B cells, indicating increased beta-oxidation of fatty acids and increased consumption of glutamine. Targeted metabolomics assays corroborated these results. The present findings identify a potential proteome signature for immune senescence in addition to previously unrecognized features of B-CLL cells and suggest that aging may be accompanied by cellular reprogramming functionally relevant for predisposing B cells to transform to B-CLL cells.

NOTCH2 links protein kinase C delta to the expression of CD23 in chronic lymphocytic leukaemia (CLL) cells

One characteristic of chronic lymphocytic leukaemia (CLL) lymphocytes is high expression of CD23, which has previously been identified as a downstream target for NOTCH2 signalling. The mechanisms regulating NOTCH2-dependent CD23 expression, however, are largely unknown. This study showed that peripheral CLL cells overexpressed transcriptionally active NOTCH2 (N2(IC)), irrespective of their prognostic marker profile. When placed in culture, NOTCH2 activity was spontaneously decreased in 25 out of 31 CLL cases (81%) within 24 h. DNA-bound N2(IC) complexes could be maintained by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) or by gamma-interferon (IFN-gamma), two CLL characteristic inducers of CD23 expression. Inhibition of PKC-delta by RNA interference or by rottlerin antagonised PMA-induced NOTCH2 activation and also suppressed NOTCH2 activity in CLL cases with constitutively activated NOTCH2 signalling. In 23 out of 29 CLL cases tested (79%), DNA-bound N2(IC) complexes were found to be resistant to the gamma-secretase inhibitor (GSI) DAPT, suggesting that GSIs will be only effective in a subset of CLL cases. These data suggest that deregulation of NOTCH2 signalling is critically involved in maintaining the malignant phenotype of CLL lymphocytes and point to a link between PKC-delta and NOTCH2 signalling in the leukemic cells.

Regulation of CD23 expression by Notch2 in B-cell chronic lymphocytic leukemia

The original observation that sera from patients with chronic B-cell lymphocytic leukemia (B-CLL) contain high amounts of soluble CD23 (sCD23), which reflect disease activity and tumor load has been confirmed by numerous reports and serial determinations of sCD23 are now recognized as important indicators of disease progression. The reason why the leukemic cells over express CD23 and subsequently release large quantities of sCD23 as compared to healthy persons or patients with other lymphoproliferative disorders is still not clear. However, progress has been made in understanding the mechanism leading to the upregulation of CD23 in the leukemic cells. Following is an update on clinical data and a short review on the potential functions of CD23 as well as its regulation by Notch2 in B-CLL.

The role of cytokines in haematopoiesis

Cytokines, by definition, exert an effect on haematopoiesis. Diseases characterized by haematopoietic insufficiency, such as aplastic anaemia, should therefore be investigated for abnormal expression of these regulatory proteins. In studies on hairy cell leukaemia, a severe deficiency was found in the production of interleukin-3 (IL-3), granulocyte-macrophage colony stimulating factor (GM-CSF), granulocyte CSF, IL-6 and tumour necrosis factor alpha (TNF alpha). Further studies on IL-6 at the mRNA and protein levels revealed that peripheral blood mononuclear cells and even hairy cells could be stimulated by interferon alpha (IFN alpha) to produce IL-6. It is interesting to speculate on the beneficial effects of IFN alpha therapy on the expansion of normal haematopoiesis and suppression or even elimination of malignant cells. Studies on a patient with angio-immunoblastic lymphadenopathy, another disease showing haematopoietic insufficiency, who developed severe aplastic anaemia, showed massive increases in IFN gamma and TNF alpha levels in serum; IL-6 and GM-CSF levels were below the limit of detection. These results correlated with an abnormal distribution of CD4+ and CD8+ T lymphocytes in the patient's blood and were compatible with the suppressive effects of IFN gamma and TNF alpha on haematopoiesis.

Effect of combined spa-exercise therapy on circulating TGF-β1 levels in patients with ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the axial joints with no satisfactory therapy. Reduction of joint pain has been reported after a course of therapy at a spa, Gasteiner Heilstollen, in Badgastein in Austria. The mechanism underlying this beneficial effect is not clearly understood and objective evidence for the biological response to therapy is lacking. The aim of this study was to find evidence for a biological response to speleotherapy in patients with AS and to study the involvement of the antiinflammatory cytokine TGF-beta1 in this response.

PATIENTS AND METHODS

83 patients with AS were treated in Badgastein for 3-4 weeks. Therapy included active exercises, hyperthermia and exposure to low doses of radon in a former mine. Response to therapy was assessed from measurement of morning pain and immunoassay of serum levels of TGF-beta1 before and after therapy. Ten AS patients who received conventional therapy and 10 patients with low back pain (LBP) served as controls.

RESULTS

A significant increase in TGF-beta1 (total and active) was found in AS patients after spa therapy. Mean concentration of total TGF-beta1 increased from 28,715 pg/ml to 43,136 pg/ml, (P<0.01) and active TGF-beta1 increased from 77 pg/ml to 1096 pg/ml (P<0.001). When the AS patients were divided into two groups according to pain reduction, group 1 (decrease in morning pain, responders: n=46) exhibited a 17-fold increase of active TGF-beta1 levels (96 pg/ml to 1654 pg/ml, P<0.0001) whereas group 2 (no change or an increase in morning pain: nonresponders: n=37), showed only 7-fold increase (53 pg/ml to 402 pg/ml, P<0.01). There was a moderate increase in active TGF-beta1 from 31 pg/ml to 42 pg/ml (P<0.05) in patients with LBP and no significant change was observed in the patients treated with conventional therapy.

CONCLUSION

These results demonstrate a significant increase in circulating TGF-beta1 in patients with AS after the combined spa-exercise therapy in Badgastein. The results also provide evidence for a biological response to speleotherapy and suggest that TGF-beta, through its antiinflammatory function, may play a role in this response.

Positive troponin T without cardiac involvement in inclusion body myositis

Cardiac troponin T (cTnT) is considered as a specific marker for acute myocardial infarction. Here, we present a case with elevated cTnT, determined by a third-generation assay, without signs of a myocardial lesion. Routine investigation of a 66-year-old female patient with indolent B-cell lymphoma revealed increased serum levels of creatine kinase (CK), MB fraction of CK (CK-MB), and cTnT, although she did not complain of cardiac symptoms. Electrocardiographic monitoring, echocardiography, magnetic resonance computed angiography, and percutaneous coronary angiography excluded myocardial damage. However, the close follow-up showed a steady increase of CK-MB and cTnT levels and gradual development of weakness in both thighs. A biopsy of the right quadriceps muscle led to the diagnosis of inclusion body myositis. In contrast to cTnT, cardiac troponin I could not be detected retrospectively in any of her serum samples. These results demonstrate for the first time that cTnT is elevated in patients with inclusion body myositis.

In vitro cytotoxic effect of proteasome inhibitor bortezomib in combination with purine nucleoside analogues on chronic lymphocytic leukaemia cells

OBJECTIVE

The anti-tumour in vitro activity of proteasome inhibitor bortezomib (PS-341, VELCADE) in combination with purine nucleoside analogues, cladribine (2-CdA) and fludarabine (FA) was tested in lymphocytes derived from 26 patients with B-cell chronic lymphocytic leukaemia (B-CLL).

METHODS

Cell viability was assessed by propidium iodide staining, and apoptosis by annexin-V and caspase activation flow cytometry assays. Additionally, expression of the apoptosis-regulating proteins Bax, Bak, Bid, Bcl-w, Bcl-2, XIAP and Mcl-1 was evaluated in B-CLL lymphocytes.

RESULTS

Bortezomib alone induced significant, dose-dependent cytotoxicity starting from the low concentration 2.5 nm, inducing apoptosis of B-CLL cells. Combination of this agent with 2-CdA or FA resulted in an increase of cytotoxicity when compared with that mediated by single drugs. The observed increase was especially evident when 5 nm of bortezomib were combined with suboptimal doses of 2-CdA or FA. The combination index (CI) was 0.87 for bortezomib + 2-CdA and 0.82 for bortezomib + FA, indicating an evident additive effect of these combinations. Moreover, B-CLL cells were more sensitive to proteasome inhibitor used alone or combined with 2-CdA or FA comparing to CD3+ lymphocytes. Corresponding to enhanced apoptosis, the expression levels of several apoptosis-regulating proteins were altered. The most pronounced changes were down-regulation of XIAP and up-regulation of Bid proteins by the combination of bortezomib with either 2-CdA or FA.

CONCLUSIONS

This study suggest that the in vitro cytotoxic effect through proteasome inhibition by bortezomib can be increased substantially with low doses of the purine nucleoside analogues, 2-CdA and FA, and that this effect on B-CLL cell is selectively higher than on normal, CD3-positive lymphocytes.

Induction of apoptosis by proteasome inhibitors in B-CLL cells is associated with downregulation of CD23 and inactivation of Notch2

Recently, proteasome inhibitors (PI) have attracted interest as novel anticancer agents in B-cell chronic lymphocytic leukemia (B-CLL). A prominent feature of B-CLL cells is the high expression of CD23, which is closely related to cell survival and is regulated by Notch2. Since several components of the Notch signaling cascade are tightly regulated by proteasomal degradation, we studied the effect of PI on Notch2 activity and CD23 expression. Exposure of B-CLL cells to PI led to induction of apoptosis, a time- and dose-dependent downregulation of CD23 expression and a decline in DNA binding of transcriptionally active Notch2. In contrast, the transcription factor NF-AT and its putative target gene CD5, which is highly expressed in B-CLL cells, were unaffected. When the late phase of PI-induced apoptosis was arrested by inhibition of caspase 3, the reduction of Notch2 activity was still observed, indicating that reduction of active Notch2 took place already during an earlier phase of apoptosis. Enforced expression of constitutively active Notch2 decreased PI-mediated apoptosis in a human B-cell line. These data indicate that downregulation of CD23 and loss of Notch2 activity are early steps in PI-induced apoptosis of B-CLL lymphocytes and may be part of the full apoptotic response.

TGF-beta1 induces bone marrow reticulin fibrosis in hairy cell leukemia

The mechanisms that lead to reticulin fibrosis of bone marrow (BM) in hairy cell leukemia (HCL) are not fully understood. We therefore investigated the involvement of TGF-beta1, a potent fibrogenic cytokine, in this process. Immunoassays revealed that TGF-beta1 is present at higher concentrations in BM, serum, and plasma of HCL patients in comparison with healthy donors (P < 0.001). RT-PCR and immunofluorescence studies showed that TGF-beta1 is overexpressed at the mRNA and protein levels in peripheral blood, spleen, and BM mononuclear cells and that hairy cells (HCs) are the main source of TGF-beta1. Active TGF-beta1 correlated significantly with grades of BM fibrosis, infiltration with HCs, and serum procollagen type III aminoterminal propeptide (PIIINP). Ex vivo studies demonstrated that TGF-beta1 significantly enhances the production and deposition of reticulin and collagen fibers by BM fibroblasts. In addition, BM plasma of HCL patients increased the synthesis of type I and type III procollagens, the main components of reticulin fibers, at the mRNA and protein levels. This fibrogenic activity of BM plasma was abolished by neutralizing anti-TGF-beta1 antibodies. These results show, for the first time to our knowledge, that TGF-beta1 is highly expressed in HCs and is directly involved in the pathogenesis of BM reticulin fibrosis in HCL.

Selection of autologous CD4+ T-cells for adoptive T-cell substitution in patients with CD23+ B-cell CLL

BACKGROUND

B-cell CLL (B-CLL) is accompanied by a progressive decrease in cellular immune functions, and treatment-related immunosuppression can further aggravate T-cell immunodeficiency. To reduce the risks of T-cell depletion, it seems feasible to collect autologous CD4+ cells at an early disease stage and subsequently reinfuse them during periods of profound T-cell depletion.

METHOD

We describe a two-step cell-selection method to obtain highly enriched CD4+ T-cells from leukapheresis compounds of patients with CD23+ B-CLL. The double selection procedure was performed using the CellPro Ceperate device, and consisted of CD4+ selection followed by CD23 purging to further remove contaminating CD23+ B-cells from the CD4+ cell fraction. The results of eight runs performed with leukapheresis material obtained from eight patients with CD23+ B-CLL at different disease stages are presented.

RESULTS

The CD4/CD23 double cell-selection procedure resulted in the purification of > 90% CD4+ cells. Median recovery of CD4+ T lymphocytes after selection was 46%, and was negatively affected by the initial tumor cell load. The final T-cell fraction still contained lymphocytes of the B-CLL clone, as determined by FACS and PCR. The cell-processing procedure had no impact on T-cell function, as assessed by the in vitro production of the cytokine interferon-gamma. Moreover, the selected CD4+ cells retained their capacity to co-stimulate mitogen-induced B-cell IgG production in vitro.

CONCLUSION

The described CD4 selection/CD23 depletion strategy is a suitable approach to obtaining high numbers of functional active autologous CD4+ T cells for adoptive T-cell transfer in patients with CD23+ BCLL.

Notch2 is involved in the overexpression of CD23 in B-cell chronic lymphocytic leukemia

Members of the Notch family encode transmembrane receptors that modulate differentiation, proliferation, and apoptotic programs of many precursor cells, including hematopoietic progenitors. Stimulation of Notch causes cleavage followed by translocation of the intracellular domain (NotchIC) to the nucleus, where it activates transcription of CBF1 responsive genes. The aim of this study was to elucidate the mechanisms leading to the overexpression of CD23, a striking feature of B-cell chronic lymphocytic leukemia (B-CLL) cells. By electrophoretic mobility shift assays, we identified a transcription factor complex (C1) that binds sequence specific to one known and 4 newly identified putative CBF1 recognition sites in the CD23a core promoter region. With the use of Epstein-Barr virus (EBV)-infected B cells as a model for CBF1 mediated CD23a expression, C1 was found to be EBV inducible. Supershift assays revealed that the nuclear form of Notch2 is a component of C1 in B-CLL cells, supporting a model in which NotchIC activates transcription by binding to CBF1 tethered to DNA. Transient transfection of REH pre-B cells with an activated form of Notch2 induced endogenous CD23a, confirming that CD23a is a target gene of Notch2 signaling. Finally, reverse transcription-polymerase chain reaction and kinetic analysis demonstrated that the Notch2 oncogene is not only overexpressed in B-CLL cells but might also be related to the failure of apoptosis characteristic for this disease. In conclusion, these data suggest that deregulation of Notch2 signaling is involved in the aberrant expression of CD23 in B-CLL.

The role of soluble CD23 in distinguishing stable and progressive forms of B-chronic lymphocytic leukemia

Soluble CD23 (sCD23) has been recognized as an important prognostic parameter in patients with chronic lymphocytic leukemia (B-CLL) at early clinical stages. There is, however, no clear information on its prognostic significance in advanced stages and on its role as an indicator for aggressive or indolent courses of disease. Therefore, sCD23 was measured in the serum of 145 patients at diagnosis and serial determinations were carried out for 8 years in 38 patients. The results indicate that in patients with identical clinical stages at first presentation the disease could take different courses depending on initial sCD23 concentrations below or above specific threshold levels (860 and 5900U/ml). sCD23 higher than these thresholds was associated with faster progression into upper clinical stages. Furthermore, sCD23-doubling time (sCD23-DT) indicated that patients with long DT progressed slowly, while those with short DT had more aggressive disease. Particularly in patients with advanced disease stages, long sCD23-DT indicated development of smoldering disease. Since sCD23 levels reflect total tumor mass, determination of sCD23-DT has probably a better predictive value than lymphocyte doubling time. It appears that B-CLL patients can be divided into different risk categories according to initial determinations of sCD23 and that sCD23-DT is an additional important parameter in predicting disease progression.

Reconstitution of endogenous interferon a by recombinant interferon in hairy cell leukemia

Recombinant human IFN alpha (rhIFN-alpha) plays an important role in the treatment of hairy cell leukemia (HCL). However, the mechanisms leading to its beneficial effect are not completely clarified, and there is no information on IFN-alpha gene expression in this disease. Therefore, we investigated the pattern of IFN-alpha gene expression and protein production in HCL and their potential regulation by rhIFN-alpha. Blood samples from 10 patients with HCL and 8 healthy donors (HD) were investigated. Expression of IFN-alpha mRNA was assessed by reverse transcription-PCR analysis in peripheral blood mononuclear cells (PBMCs) under basal conditions and on induction with rhIFN-alpha and polyionosinic-polycytidylic acid [poly(I.C)]. IFN-alpha concentrations in plasma and culture supernatants were measured by immunoassays, and intracellular IFN-alpha was evaluated by fluorescence-activated cell sorting analysis. Results showed that, in contrast to blood samples from HDs, freshly isolated PBMCs from un treated HCL patients did not express IFN-alpha mRNA, whereas IFN-alpha transcripts were found in patients who were under rhIFN-alpha therapy Plasma of untreated patients contained no, or extremely low levels of IFN-alpha as compared with plasma of treated patients and HDs. Ex vivo treatment of PBMCs with rhIFN-alpha or poly(I.C) resulted in a remarkable up-regulation of IFN-alpha at the mRNA and protein level. In HCL, however the amounts of IFN-alpha protein remained less than in HD. Inhibition of IFN-alpha transcription was found after exposure of PBMCs to serum fron untreated patients. Finally, a reduced capacity to produce IFN-alpha was found within B- cell, T-cell, and monocyte compartments in HCL patients which could be enhanced by rhIFN-alpha. The results demonstrate the ability, of rhIFN-alpha to up-regulate the expression of IFN-alpha gene and protein production and suggest that priming the production of endogenous IFN-alpha is a critical step in the mechanism of action of rhIFN-alpha in HCL.

Basic fibroblast growth factor is expressed by CD19/CD11c-positive cells in hairy cell leukemia

Several features are characteristic for hairy cell leukemia (HCL). Among those are pancytopenia, bone marrow fibrosis, and the appearance of a defined tumor cell phenotype in peripheral blood (PB), bone marrow (BM), and spleen. Hairy cells (HC) coexpress antigens specific for B lymphocytes and monocytes/macrophages and thus the malignant cell does not seem to be restricted to a defined lineage. When serum or bone marrow aspirate was screened by enzyme-linked immunosorbent assay (ELISA) for basic fibroblast growth factor (bFGF), specimen derived from HCL (serum: mean value, 29 pg/mL; BM aspirate: mean value, 641 pg/mL) contained significantly higher levels than those from healthy subjects. To study whether peripheral blood mononuclear cells (PBMC) derived from patients suffering from HCL and healthy donors (HD) were capable of producing bFGF, culture supernatant (conditioned medium, [CM]) was tested for the presence of this cytokine. While bFGF was not detectable in cell cultures from HD, HCL-derived CM contained relatively high levels of bFGF. CM was successfully used for stimulation of mesenchymal cell proliferation, which could be inhibited by a neutralizing anti-bFGF antibody. Cellular activation by pokeweed mitogen (PWM) or the combination of 12-o-tetradecanoyl-phorbol-13-acetate (TPA) plus calcium ionophore (Ca-Ip) led to an enhanced mRNA expression. Results of Western blot experiments showed that HC synthesize at least three isoforms (approximately 18, 23, and 25 kD), but only the 23-kD isoform is exported. To assess the nature of the producer cell, double immunofluorescence analysis using a bFGF-specific and an anti-CD11c monoclonal antibody (MoAb) was undertaken. The majority of cells scoring positive for CD11c were also reactive with the anti-bFGF MoAb. Furthermore, enrichment of CD19/CD11c-positive cells correlated with enhanced bFGF levels, thereby supporting the argument for HC being the producer cells of bFGF. A biological function of bFGF in HCL might be mediation of chemoresistance, as 2-chlorodeoxyadenosine (2-CdA)-induced inhibition of cell proliferation can be reversed by bFGF. Endogenous bFGF production by HC is not affected by this purine analogue and 2-CdA-induced apoptosis is diminished in bFGF-producing HC as compared with normal PBMC. Therefore, bFGF expression by HC might be important for resistance to chemotherapy and survival of the malignant cells.

Inadequate production of hematopoietic growth factors in hairy cell leukemia: up-regulation of interleukin 6 by recombinant IFN-alpha in vitro

The course of hairy cell leukemia (HCL) is characterized by progressive pancytopenia. The pathogenesis of this phenomenon is still not fully understood. To study if the decrease in hematopoiesis in HCL is accompanied by abnormal concentrations of growth factors, we investigated the production of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, interleukin 3 (IL-3), interleukin 6 (IL-6), and tumor necrosis factor alpha by peripheral blood mononuclear cells (PBMCs) of eight patients with HCL. The results point to a severe deficiency of production of all cytokines tested as compared to healthy donors. However, enrichment of autologous monocytes by counterflow centrifugation resulted in a marked increase of the levels of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, IL-6, and tumor necrosis factor alpha. The most pronounced effects were seen with IL-6. Reverse transcription-PCR analysis indicated that pokeweed mitogen, IFN-alpha, and poly(I:C) are capable of inducing the expression of IL-6-specific mRNA in HCL cells. These findings are substantiated on the protein level by immunofluorescence analysis. Incubation of PBMCs with IFN-alpha resulted in a significant increase of intracellular IL-6 in HCL but not in healthy donors. This increase was also seen in hairy cells positive for CD19 and CDllc. Furthermore, IFN-alpha induced the secretion of IL-6 from PBMCs of HCL patients but not healthy donors. In conclusion, our studies with PBMCs from patients with HCL revealed an inadequate supply of hematopoietic growth factors that might, in part, be due to the monocytopenia characteristic for this disease. The findings also indicate that IFN-alpha is capable of inducing the production of IL-6 in the patients' PBMCs as well as in their hairy cells. These data from our in vitro studies support the clinical observation that treatment with IFN-alpha leads to reconstitution of hematopoiesis.

Myelosuppression in HCL: role of hairy cells, T cells and haematopoietic growth factors

To elucidate mechanisms which may be responsible for the haematopoietic insufficiency in hairy cell leukaemia (HCL), we investigated in an autologous in vitro system the influence of haematopoietic growth factors (CSFs) and the effects of hairy cells (HCs) as well as T cells on the formation of haematopoietic colonies (CFU). Colony forming assays were performed using peripheral blood mononuclear cells (PBMC) of 6 HCL patients. To remove HCs, PBMCs were subjected to complement-mediated lysis, T cells were removed by E-rosette formation. Assays were done with and without recombinant human (rh) interleukin-3 (IL-3) and rh granulocyte-macrophage-colony-stimulating factor (GM-CSF). All 6 patients exhibited a severe reduction of their circulating progenitor cell (CPC) compartment. There was no correlation between the degree of colony reduction and the number of HCs. However, a correlation was found between the numbers of CPCs of HCL patients and healthy donors and the monocyte counts in these groups (r = 0.8573, p < 0.001). The removal of autologous HCs, but also of T cells, resulted in a significant increase in colony formation (BFU-E, CFU-GM, CFU-mix). In none of the experiments, however, did colony numbers come close to the normal range. This was only achieved by supplementation of the culture medium with rh IL-3 and rh GM-CSF. The results suggest that the haematopoietic failure observed in HCL patients is probably due to an inadequate supply of CSFs as well as to an inhibitory activity of HCs and T cells which might exert their effects in a synergistic fashion. There is also evidence that the lack of monocytes plays a role in the development of the haematopoietic insufficiency in HCL.

Evidence of colony suppressor activity and deficiency of hematopoietic growth factors in hairy cell leukemia

The cause of myelosuppression in hairy cell leukemia (HCL) has been ascribed to a reduction of the circulating progenitor cell (CPC) compartment and to suppression of hematopoiesis by TNF-alpha. The present study was performed to evaluate the inhibitory effect of hairy cells (HCs) and a possible lack of hematopoietic growth factors on the number of autologous CPCs in vitro. In initial experiments the number of circulating BFU-E, CFU-GM and CFU-mix in HCL patients was found decreased. Monocytopenia but not the number of circulating HCs correlated to the degree of colony reduction in our patients. This pointed to a lack of colony stimulating factors (CSFs) in HCL. Actually, the growth of BFU-E, CFU-GM, and CFU-mix improved upon the addition of IL-3 and GM-CSF in HCL patients but not in healthy donors. To test the suppressive role of HCs in our assay system, cultures were performed after removal of autologous HCs. The results showed that in HC-depleted cultures the numbers of BFU-E, CFU-GM, and CFU-mix were significantly higher. This inhibitory effect of HCs could partially be neutralized by the addition of monoclonal antibodies against TNF-alpha. When the assays were performed with the removal of HCs and the addition of CSFs normal progenitor cell counts were detected in most patients. We conclude that HCs mediate the inhibition of colony growth in part by TNF-alpha. Monocytopenia is related with a deficiency of CSFs in this disease. The reduced colony growth in HCL, therefore, is due to both the inhibitory effects of HCs and the deficiency of CSFs. We suppose that the CPC-compartment is actually preserved in this disease.

Beta 2-microglobulin. A reliable parameter for differentiating between graft rejection and severe infection after cardiac transplantation

We investigated the role of beta 2-microglobulin as a noninvasive parameter to monitor acute rejection and severe infection in 45 consecutive heart transplant recipients. Endomyocardial biopsy revealed moderate (41 patients) or severe (three patients) rejection in 44 patients. Severe infections of bacterial septicemia (11 patients), bronchopneumonia (two patients), and viral infection (seven patients) were detected by a meticulous schedule of various clinical and laboratory tests. beta 2-Microglobulin levels in serum, generally corrected for serum creatinine, were significantly elevated in patients with infections (median, 6.3 mg/l; range Q10-Q90, 3.47-10.27 mg/l) compared with levels in patients with rejection (p less than 0.0001) or in patients in obviously good condition (p less than 0.0001). At the onset of acute rejection, the median corrected beta 2-microglobulin serum level was 1.56 mg/l (range Q10-Q90, -0.05-3.46 mg/l) and was significantly different from the control group (p less than 0.01). In addition, density function and empirical quantile analyses allowed us to define ranges of beta 2-microglobulin levels that would differentiate between rejection (2.05-3.46 mg/l) and infection (greater than 3.46 mg/l). With these values, sensitivity and specificity were 0.9 and 0.938 for detection of infection and 0.23 and 0.925 for detection of rejection, respectively. By means of beta 2-microglobulin, two cases of infection were misinterpreted as rejection (10%), and four of 44 rejections were mistaken for infections (9%). We conclude that measurements of beta 2-microglobulin may improve the management of heart transplant patients.

Long-term remission in a patient with erythroleukemia following interferon-alpha treatment

A patient in second relapse of acute erythroleukemia (AEL) was treated with 10 MU of recombinant interferon (IFN)-alpha subcutaneously for 24 days after he had failed standard chemotherapy. Besides fever up to 38.9 degrees C and a transient raise in liver function parameters, treatment was well tolerated but had to be discontinued because of a severe decrease in white blood cell and platelet count. After termination of IFN treatment, both cell populations showed a continuous rise during the following weeks and hemoglobin increased concomitantly. Partial remission could be reached as was demonstrated by a decrease in PAS-positive erythroblasts in bone marrow biopsy. Further studies with IFN in patients with AEL refractory to cytostatic chemotherapy are recommended.

Duration of first remission as an indicator of long-term survival in chronic myelogenous leukaemia

Approximately 31 patients with chronic myelogenous leukaemia (CML) are documented in the literature who survived more than 10 years after diagnosis. We present a CML-patient whose survival of 27 years is probably the longest reported so far. The analysis of the course of disease in these patients revealed that the duration of unmaintained first remission after chemotherapy is of high prognostic significance. In 17 of 24 evaluable patients the remission lasted more than 1 year and in another five at least 6 months (mean 73.8 months, range 0-240 months). In most patients busulfan was used as initial therapy. There was no correlation between the amount of drug given and the duration of remission or survival. Other parameters such as sex, age, initial leucocyte counts, differential count, haemoglobin, platelet count or spleen size seemed to have no prognostic relevance. While approximately 25% of CML patients with typical duration of survival exhibit a Ph1 chromosome mosaicism only, this finding was present in nearly half of the long-term survivers.

[Mechanism of action of interferon-alpha 2 in hairy cells and lymphoblastoid cell lines: the significance of type I interferon receptors and RNA synthesis]

Lymphoblastoid cells were subjected to Western Blot analysis for detection of Interferon-alpha-binding proteins. JOK-1 cells--a human hairy cell leukemia line--revealed three proteins with apparent molecular weights of 120, 100 and 32 kD, respectively. Down-regulation of the receptor was observed. A differential binding pattern of two proteins (100 and 85 kD) was observed in T-CLL, whereas no signal detection was achieved in B-CLL. Mononuclear cells from 6 patients with hairy cell leukemia and 6 patients with CLL were found to differ significantly in terms of nucleic acid precursor incorporation.

Interferon alpha-2 for hairy cell leukemia: evidence for induction of RNA synthesis in hairy cells and failure to correlate enhancement of natural killer cells with elimination of hairy cells

The effect of human recombinant interferon alpha 2 (IFN alpha 2) on hairy cells obtained from 16 patients was evaluated. All patients promptly responded to induction of remission with 2 X 10(6) U/m2 interferon alpha 2 b, three times a week, sc. In order to achieve a more detailed insight into the mode of action of interferon in this disease, we determined the influence of IFN alpha 2 on the incorporation of radiolabeled thymidine and uridine into hairy cells. While both 3H-thymidine and 3H-uridine incorporation were unaffected by IFN alpha 2 in a 3-hour incubation period, a significant increase in uridine incorporation into hairy cells, but not CLL cells, was observed after 24 h. Cell surface marker analysis performed with monoclonal antibodies did not reveal a quantitative alteration of the immunophenotype of hairy cells in vitro. In addition, natural killer cells, assessed by monoclonal antibodies and a cytotoxicity assay against K 562 cells, were found to be decreased in 9 out of 10 patients prior to therapy. Although IFN alpha 2 could stimulate natural killer cells in vivo, we did not find a consistent correlation between the activation of these cells and the response to therapy. We conclude, therefore, that NK cells play no major role in the regression of hairy cells. Furthermore, IFN alpha 2 does not alter antigenic determinants in vitro, but leads to an enhanced incorporation of 3H-uridine into hairy cells in vitro, thus indicating a possible role for the induction of RNA synthesis in vivo.

[Recombinant (IFN-alpha 2b) therapy in hairy cell leukemia]

Eighty-five patients with hairy-cell leukemia were treated in a multicentric "open label" study with IFN-alpha 2b and evaluated. Induction therapy was 2 X 10(6) U IFN-alpha 2b/m2, 3 times a week, s.c. The results show this regimen to be highly effective with only a few tolerable and transient side effects consisting mainly of flu-like symptoms. After 6 months of therapy 4% CR, 69% PR, and 16% MR, were noted. In a small group of four patients who had achieved CR or PR, we tested the effect of varying doses for maintenance therapy. Our preliminary results indicate that a relapse caused by interruption of IFN therapy or dose reduction to 3 X 10(6) U given once a week, o.c. could be successfully treated by readministration, or escalating the dosage of IFN. It seems that remission maintenance requires long-term treatment with IFN. In a short-term in vitro test we studied the effect of IFN-alpha 2 on the incorporation of 3H-thymidine and 3H-uridine into hairy cells of five patients. Fort both precursors no appreciable effect was detected. However, after prolonged incubation for 48 h, a significant enhancement of 3H-uridine incorporation was observed, while 3H-thymidine incorporation remained unaffected. Cell marker analysis performed with monoclonal antibodies before and after incubation of hairy cells with IFN-alpha 2 for up to 7 days did not reveal any change of the phenotype of hairy cells.

Effect of alpha 2-interferon on hairy cells and cell lines: a role for type I interferon receptors and RNA synthesis

The binding of alpha 2-interferon to highly purified plasma membrane proteins of malignant human lymphoid cells was assessed by Western Blotting. The human hairy cell leukemia cell line JOK-1 revealed three major alpha-interferon binding proteins with molecular weights of 120, 100, and 32 kD. Pretreatment of JOK-1 cells with alpha-interferon in vitro results in a disappearance of these proteins, which is in concordance with receptor down-regulation on JOK-1 cells. In a case of T chronic lymphocytic leukemic (CLL), a differential binding pattern of two proteins with 100 and 85 kD was observed, whereas a case of B-CLL did not yield any signal detection. In addition, mononuclear cells from patients with hairy cell leukemia and CLL were found to differ with respect to the in vitro incorporation of nucleic acid precursors. alpha 2-Interferon enhances [3H] uridine incorporation into hairy cells, whereas this phenomenon can be detected in CLL cells only to a much lesser extent.

Effects of prednisolone on beta-adrenergic desensitization of normal peripheral lymphocytes: an in vitro model for steroid-controlled tachyphylaxis

In vitro culture of human peripheral blood lymphocytes with the beta-adrenergic catecholamine isoproterenol for 24 hours, induced homologous beta-adrenergic desensitization, i.e. a large decrease in the number of beta-adrenergic binding sites and loss of the adenylate cyclase response to isoproterenol, without altering the effectiveness of prostaglandin E1 to stimulate the enzyme. Lymphocyte cultures pulsed for 24 hours with isoproterenol, washed free of the agent and cultured in hormone-free medium for 48 hours still showed marked suppression of the beta-adrenergic adenylate cyclase response and a lack of beta-receptors. When prednisolone was added to the isoproterenol-depleted resuspension medium of desensitized lymphocytes, however, the beta-adrenergic system recovered fully within 48 hours. Treatment of desensitized lymphocytes with prednisolone in the continuous presence of isoproterenol failed to restore beta-adrenergic responsiveness of the cells. The results are discussed with respect to the reconstituting effect of prednisolone on beta-adrenergic responsiveness in bronchial asthma after therapy induced tachyphylaxis.

Acute leukemia with mediastinal mass, lymphadenopathy, and monocytic precursor cells

Cell marker analysis with monoclonal antibodies (MoAb) as well as differentiation studies with the chemical inducer TPA were used to identify a population of apparently lymphoid cells as monocytic precursor cells in a patient with acute leukemia. The initial manifestation of the disease with mediastinal mass and lymphadenopathy was followed by the appearance of small lymphocyte-like blast cells in bone marrow (BM) and peripheral blood (PB). Although a lymph node biopsy revealed an infiltration with monoblasts, the leukemic cells in BM and PB were not classifiable. However, when the patient relapsed after chemotherapy with large monoblasts and again with morphologically lymphoid blast cells, the latter could be classified by treatment with TPA. After incubation with the inducer (12-48 hr) the cells became positive with the MoAB VIM-D5, showed a strong reaction with alpha-naphthyl-acetate-esterase and developed macrophage like morphology, as well as phagocytic properties. During the terminal phase of the disease, small, lymphocyte-like blast cells predominated. These cells could be classified by a panel of MoABs. They expressed myeloid determinants (VIM-D5, VIM-2, MY 9, VIM-12, VIM-13) but showed no reactivity with MoABs specific for lymphocytic cells.

B-immunoblastic lymphoma arising in angioimmunoblastic lymphadenopathy

We present a female patient with a B-immunoblastic lymphoma of the IgM-lambda type arising in angioimmunoblastic lymphadenopathy. An increased ratio of helper/inducer to suppressor/cytotoxic lymphocytes in the lymph node could have triggered the proliferation of B cells. Evolution of IgM cryoglobulinemia was paralleled by malignant transformation in the lymph node. A short-term in vitro chemosensitivity test could predict response to COP combination chemotherapy suggesting that in vitro chemosensitivity testing can be useful for the therapeutic management of angioimmunoblastic lymphadenopathy.

Noninvolvement of chromosome 16 in karyotype evolution of acute myeloid leukemia in a patient with a heritable fragile site on 16q22

A fragile site on the long arm of chromosome #16 (q22) was detected in a 24-year-old man with pancytopenia. During the course of the disease he developed an inverted duplication of region q11-12 of chromosome #1 and a translocation between chromosomes #9 and #13: t(9;13)(p22;q32). These abnormalities, as well as an additional iso-like marker chromosome that consisted of one normal 9p and the abnormal 9p arm, were detected in Epstein-Barr nuclear antigen-positive B-cell cultures. Two years later, evolution of the abnormal clone with loss of chromosome #7 and, subsequently, chromosome #22 occurred in connection with development of acute myeloid leukemia. Although the heritable fragile site on chromosome #16 was present in all cell populations investigated, it was not involved in the evolution of the abnormal karyotype. This fragile chromosome #16 also was found in 4 of 11 family members in whom chromosome analysis was performed, thus suggesting this aberration was inherited in a dominant autosomal pattern. The incidence of the heritable fragile site in normal and leukemic cells of the patient, as well as stimulated blood cultures of his relatives, are reported. In addition, the possible relationship between this constitutional chromosome breakage syndrome and the occurrence of leukemia is analyzed.

Prediction of the response to chemotherapy in acute leukemia by a short-term test in vitro

To detect sensitivity or resistance of leukemic cells to chemotherapy prior to treatment, a short-term incubation method was employed. Blast cells from the peripheral blood or bone marrow of adult patients presenting with different forms of acute leukemia were analyzed for in vitro responsiveness to anticancer drugs in terms of suppression of 3H-uridine incorporation into cellular nucleic acids. The following agents were tested over a wide range of concentrations: Adriamycin, cytosine arabinoside, thioguanine, 6-mercaptopurine, prednisone, and 4-hydroperoxycyclophosphamide. Retrospectively, the in vitro data were compared to the clinical response of the patients to polychemotherapy. In the majority of the patients, in vitro cytotoxic effectiveness of Adriamycin (doxorubicin) and cytosine arabinoside reflected the in vivo situation. The levels of in vitro inhibition that could distinguish between drug-sensitive and drug-resistant diseases appeared to be 30% for Adriamycin and 20% for cytosine arabinoside. No correlation was found between the Adriamycin effect in vitro and the proliferative state (rate of 3H-thymidine incorporation) of the leukemic cell population. Serial in vitro sensitivity testing during the course of disease of various patients proved the ability of the test system to detect acquired resistance to chemotherapeutic agents. Therefore, the assay might serve as a reliable tool in the selection of effective chemotherapy in individual patients suffering from acute leukemia.

Short-term in vitro sensitivity testing in acute leukemia

To detect sensitivity or resistance of leukemic cells to chemotherapy prior to treatment, a short-term incubation method was employed. Blast cells from the peripheral blood or bone marrow of adult patients with different forms of acute leukemia were analyzed for in vitro responsiveness to cytostatic agents in terms of suppression of nucleoside precursor (3H-uridine, 3H-deoxyuridine) incorporation into the cells. Retrospectively, the in vitro data were compared to the clinical response of the patients to polychemotherapy. In the majority of patients, in vitro cytotoxic effectiveness of doxorubicin and ara-C reflected the in vivo situation. The levels of in vitro inhibition that could distinguish between drug-sensitive and drug-resistant diseases appeared to be 30% for doxorubicin and 20% for ara-C. No correlation was found between the doxorubicin effect in vitro and the proliferative state of the leukemic cell populations. Serial in vitro testing during the course of the disease of various patients proved the ability of the test system to detect acquired resistance to chemotherapeutic agents. Studies with established cell lines (HL-60, Raji) indicated that the short-term test in its present form is probably not suited to monitor the effect of drug combinations in vitro.

Investigations on karyotype evolution in patients with chronic myeloid leukemia (CML)

In an attempt to relate karyotype evolution to clinical and hematological data serial chromosomal analyses were performed in 31 patients with chronic myeloid leukemia (CML), both in chronic and acute phases. Our results in Philadelphia chromosome (Ph1)-positive CML are in line with karyotype profiles described in the literature. In addition, we report on chromosomal findings in 4 cases of Ph1-negative disease, one presenting with an iso17q chromosome in the positive CML. The same chromosomal abnormality was observed in a small population of Ph1-negative cells present in one of two patients with mixed Ph1-positive/Ph1-negative CML. The first case of a female patient with the loss of a sex chromosome in Ph1-positive cells is reported. Two patients with unusually long and mild chronic phases despite the presence of trisomy 8 in their karyotypes are described. Our findings suggest that the order of appearance of additional chromosomal changes of CML is of prognostic significance for the progression and the clinical picture of the disease.

beta-Adrenergic responsiveness of human peripheral lymphocytes after mitogenic transformation with phytohemagglutinin

In vitro transformation of human peripheral blood lymphocytes with the mitogen phytohemagglutinin did not alter the total number of beta-adrenergic binding sites for (+/-)-125iodocyanopindolol on the surface of intact cells, whereas binding to membrane fragments of transformed cells appeared to be diminished. In isolated membranes, there was also a marked decrease in basal, fluoride- and hormone-stimulated adenylate cyclase activity after phytohemagglutinin treatment. In whole cells, however, a lowering effect of phytohemagglutinin on levels of cyclic adenosine 3',5'-monophosphate was not apparent. The discrepancy between data on intact and broken cells indicates that the transformed cells do not acquire additional beta-adrenergic receptors or catalytic adenylate cyclase as their cell surface expands due to blastogenesis. It is therefore concluded that mitogenic transformation of human peripheral lymphocytes does not cause specific changes in the beta-adrenergic/adenylate cyclase system.

Differences in beta-adrenergic receptor density and adenylate cyclase activity between normal and leukaemic leukocytes

An identical class of high-affinity binding sites for the 125I-labelled beta-adrenergic antagonist hydroxybenzylpindolol, was identified on intact human normal and leukaemic peripheral blood leukocytes. On normal unfractionated lymphocytes, polymorphonuclear leukocytes, and monocytes, receptor density did not differ significantly (1200-1400 receptors per cell; P greater than 0.3), but it was higher on B- than on T-lymphocytes (P less than 0.05). In leukaemia, monocytic blast cells expressed highest receptor numbers, whereas very low receptor density was seen on the pathologic B-cells from chronic lymphocytic leukaemia. Among normal leukocytes, adenylate cyclase activation by hormones (isoproterenol, prostaglandin E1, histamine) and sodium fluoride was strongest in plasma membranes from monocytes, but very weak in polymorphonuclear leukocytes either due to uncoupling of hormone receptors from adenylate cyclase or to low catalytic activity. In T-cells, enzyme activity was significantly lower than in B-cells. Loss of adenylate cyclase sensitivity to hormones and fluoride occurred in leukaemic cells from chronic and acute lymphocytic leukaemia.

Distinct lymphoblastic and myeloblastic populations in TdT positive acute myeloblastic leukemia: evidence by double-fluorescence staining

Double-immunofluorescent staining for the enzyme terminal deoxynucleotidyl transferase (TdT) as a marker of primitive lymphoblasts, and for the VIM-D5 antigen as a differentiation antigen of the myeloid system gave direct evidence for distinct lymphoblastic and myeloblastic populations (mixed leukemic cell populations) in seven patients with acute leukemia. The percentage of malignant TdT positive cells contributing to a leukemic cell bulk with unequivocal signs of myeloid origin was between 10 and 80%. A defect at the level of a common progenitor cell giving rise to both the TdT and the VIM-D5 positive blast cell population is discussed.

[Chromosome analysis and TdT determination: important prognostic parameters of blastic crises in chronic myelocytic leukemia]

To detect karyotype changes during the chronic phase of CML, 31 mostly Ph1-positive patients were followed cytogenetically over a period of 3 years. Newly emerging abnormalities, e.g. second Ph1-chromosome, iso17q, trisomy 8, could be correlated with clinical and hematological characteristics of the course of the disease if they constituted the first additional chromosomal change. In 54 patients with suspected or established blast crisis, TdT determinations were performed. Out of 27 patients with verified blast crisis, 6 showed markedly elevated enzyme activities in the leukemic blast cells. These patients proved to be very sensitive to cytostatic therapy with prednisone and vincristine. The continuous observation of TdT levels enabled us to initiate a controlled and, with respect to the quality of life, a less toxic therapy. Our data indicate that serial chromosomal analyses and TdT determinations are of great value in predicting prognosis and therapeutic responsiveness in CML.

Non-specific uptake of the radioligand 125I-IHYP by intact human lymphocytes: reversal of the uptake process

Binding of (+/-)[125I]iodohydroxybenzylpindolol (IHYP) to beta-adrenoceptors on intact human peripheral blood lymphocytes was found to be associated with a high degree of non-specific intracellular uptake of the radioligand. Non-specific binding on cellular surfaces was identified by displacing IHYP from its specific binding sites with the cold competing antagonist (+/-)-propranolol. Another methodological approach, however, was necessary to eliminate the uptake problem: release of intracellularly accumulated IHYP was achieved by sedimentation of the IHYP-loaded cells and resuspension in hypotonic buffer (HME buffer) for 10 min at +4 degrees C. The true value of maximal IHYP binding measured after IHYP release was 970 binding sites/cell as compared with 2300 receptors/cell found under standard binding conditions. This difference in maximal IHYP binding obtained by the 2 methods is attributed to the strong interference of the uptake process with the measurement of specific IHYP binding. Further evidence for the efficiency of the procedure to reverse the uptake process was obtained with the very slowly dissociable beta-adrenoceptor antagonist FM 24. Pre-incubation of the cells with 5 x 10(-5) M FM 24 totally prevented specific IHYP binding. Any IHYP measured on cells in the presence of FM 24, therefore, must have been due to mere non-specific binding and cellular uptake of the radioligand. Even though the uptake of IHYP was enhanced in FM-24-treated cells, this influx could be completely reversed by exposing the IHYP-loaded cells to HME buffer for 10 min at +4 degrees C. Our findings indicate that our experimental conditions are suitable for beta-receptor binding studies on intact cells with IHYP, because the uptake of the labeled ligand is eliminated.

[Chronic lymphatic leukemia of B-cell type: clinical and morphological investigations for diagnostic differentiation (author's transl)]

Chronic lymphatic leukemia (CLL was diagnosed in 71 patients based on clinical data. Most of the patients were in the stages 0, I and II, only 18% were in the stages III and IV according to Rai. In all cases, the disease was characterized by an increased number of B lymphocytes (B-CLL). The B cells mostly expressed a weak fluorescence intensity when tested for membrane bound immunoglobulins (Ig). In accordance to that, the quantitative measurement of Ig in the serum revealed a decrease of one or more Ig classes in 72% of the patients. No correlation existed between the number of b lymphocytes (and T lymphocytes) or the Ig concentration in the serum and the stage of the disease. To distinguish the CLL from related lymphoproliferative disorders, especially the immunocytic lymphoma, lymph node biopsies were examined histologically and immunomorphologically for intracytoplasmic Ig. This examination confirmed the diagnosis of CLL in 33 out of 40 cases. Six lymph nodes were classified as immunocytic lymphoma of the lymphoplasmacytoid type. In three of the latter, the immunocytic lymphoma was clinically associated with decreased Ig concentrations in the serum. These findings emphasize that the clinically established diagnosis of CLL should be corroborated by immunomorphology.

Phenotypic changes in a case of blast crisis of CML: characterization by TdT, cytochemistry, and cytogenetics

Phenotypic changes in blast crisis of a case of Philadelphia chromosome (Ph1)-positive chronic myelogenous leukaemia were characterized by serial terminal transferase (TdT) determinations simultaneously related to cytochemical and cytogenetic data. At the onset of the blast crisis, 90% of the blast cells were acid phosphatase-positive (focal pattern), Ph1-positive, lymphoid cells. The TdT activity amounted to 29 units/10(8) mononuclear cells in the peripheral blood and to 57 units/10(8) mononuclear cells in the bone marrow. Therapy with vincristine and prednisone caused the elimination of the TdT-positive cell population. 4 months later, there was an increase in TdT-negative, myeloid blasts which was brought under control with busulfan. Cytogenetic analysis of the myeloid blasts still revealed Ph1 positivity in 100% of the metaphases examined and the lack of additional chromosomal abnormalities. A second relapse was again dominated by TdT-containing cells with the 46,XX,Ph1 karyotype. This time, the patient failed to achieve remission with vincristine and prednisone. Even though the TdT activity was markedly decreased, the lymphoid blast count remained elevated and the cells showed resistance to further therapy. This failure of morphology, cytochemistry as well as cytogenetics to distinguish between the individual phenotypes emerging during the course of blast crisis of CML characterized the TdT as a cell marker of important diagnostic and therapeutically prognostic value.

Proliferation kinetics of Sézary cells

The proliferation kinetics of neoplastic T cells arising in Sézary syndrome (Sézary cells) are still poorly understood. Kinetic studies with 3H-thymidine as a DNA precursor revealed a low incorporation rate of the nucleotide into Sézary cells obtained from the peripheral blood versus Sézary cells from the skin. Using the double-label autoradiography we determined the duration of single cell cycle phases of blood and cutaneous Sézary cells. The results indicate the almost complete lack of proliferative activity in the blood but a considerable portion of proliferatively active Sézary cells in skin infiltrates. The removal of a large mass of quiescent blood cells by leukapheresis did not affect the proliferative state of the residual peripheral cell population implying that the procedure did not induce the migration of proliferating skin cells towards the blood. Terminally, the disease underwent transition into immunoblastic lymphoma. At this time, the kinetic behavior of the peripheral immunoblasts showed great similarity to that of cutaneous Sézary cells. The findings point towards a common extravascular production site of Sézary cells and immunoblasts probably located in the lymphatic tissue.

[New aspects in oncological research (author's transl)]

Following the presentation of some theories of cancer etiology the significance of the cell membrane in neoplastic transformation is stressed. Alterations of the cell surface are blamed responsible for the abnormal proliferative behaviour and metastasis of cancer cells. In addition, the disturbance of membrane-bound receptor structures might result in defects of "endocrine" control mechanisms leading to the typical uncontrolled growth of tumor cells. In this context, the membrane-bound adenylate-cyclase system deserves special interest, since hormone impulses stimulate this enzyme via specific receptors to produce cyclic AMP. This nucleotide transmits hormonal signals within the cell. Our own studies on lymphoma and leukemic cells are mentioned because they demonstrate alterations of the cAMP producing system in malignant cells. Finally, the phenomenon of cell fusion is discussed. Recently great attention has been paid to this technique, since hybridization experiments enable us to get new insight into the process of neoplastic transformation.

Reconstitution of catecholamine-sensitive adenylate cyclase activity: interaction of components following cell-cell and membrane-cell fusion

Heterokaryons formed by the fusion of adenylate cyclase-deficient S49 cells and beta-adrenergic receptor-deficient B82 cells in the presence of cycloheximide display a catecholamine-sensitive adenylate cyclase activity. Similar complementation can be observed when receptor-replete membranes from the cyclase-deficient cell are fused with intact B82 cells. Using the cell fusion technique it can be demonstrated that the uncoupled S49 cell variant has a functional beta-adrenergic receptor but that this variant and the adenylate cyclase-deficient variant are not complementary. Hypothetically, both clones may share a common defect in regulatory components of adenylate cyclase or both may lack a specific coupling factor.