hCNT1 in Waldenström’s macroglobulinemia (WM) and small lymphocytic lymphoma (SLL) patients (pts): A possible predictive biomarker of 2-chloro-2`-deoxyadenosine (2-CDA) clinical activity

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Background: The resistance mechanism to 2-CDA is not completely known. In this study we used pharmacogenomic to identify genetic factors that influence drug response and to better investigate 2-CDA complex intracellular metabolism. Methods: Using Real-time PCR method (ABI-PRISM 7000 machine) we amplified seven genes, encoding for equilibrative and concentrative nucleoside transporter (hENT1, hCNT1), deoxycytidine and deoxyguanosine kinase (dCK, dGK), 5`-nucleotidase (5`NT), ribonucleotide reductase catalytic and regulatory (RR1, RR2) subunits, in bone marrow (BM) at baseline of 17 pts with WM or SLL in order to verify the correlation between gene expression and clinical outcome. All pts were treated with a combination therapy (2-CDA 0.1 mg/kg sc injection and Rituximab at standard schedule). Quantitation was performed using the Delta CT calculation: the value of gene expression was normalised to the calibrator (healthy tissue cells). Results: hCNT1 and 5’NT gene expression analysis has shown lower values in pts than in controls. The other markers didn’t show any significance. Two pts achieving partial remission (PR) presented 100 times lower hCNT1 levels (median 6.8*10−4, range 6.8–6.9*10−4) than pts (n = 10) in complete remission (median 7.9*10−2, range 0.1–4.6*10−1; p = 0.03). Conclusions: hCNT1 seems to be the most important gene involved in 2-CDA clinical activity and its expression may correlate with prognosis. Compared to controls, the low plasmatic RNA level of hCNT1 exhibited by our pts doesn’t seem to be predictive of lack of clinical activity of 2-CDA. However the lower level of hCNT1 plasmatic expression detected in the two pts who achieved only PR could suggest a possible relationship between reduced hCNT1 plasmatic expression and a diminished clinical activity of 2-CDA. Thus it might be important to explore the possibility of standardizing a quantitative method in order to identify a threshold value which could be predictive of drug resistance.

No significant financial relationships to disclose.

Human immunodeficiency virus transactivator protein (Tat) stimulates chemotaxis, calcium mobilization, and activation of human polymorphonuclear leukocytes: implications for Tat-mediated pathogenesis

The extracellular activities of the human immunodeficiency virus (HIV) transactivator protein (Tat) include induction of angiogenesis and stimulation of monocyte migration. Here it is shown that polymorphonuclear leukocytes (PMNL), mostly neutrophils, rapidly invade in response to Tat in vivo and initiate the formation of new vessels. In vitro, Tat was chemotactic for PMNL and induced calcium (Ca(2+)) mobilization. Tat proteins with inactivating substitutions in the arginine-glycine-aspartic acid or basic domain were still active in inducing PMNL migration, whereas Tat peptides mapped the migration and Ca(2+) mobilization activity to a cysteine-rich core domain, previously described as a Tat "chemokine-like" region (peptide CysL(24-51)). Tat and the CysL(24-51) peptide also induced PMNL superoxide production and the release of the angiogenic factors interleukin-8 and vascular endothelial growth factor from PMNL. CysL(24-51) did not induce endothelial cell migration but was angiogenic in vivo. These data indicate that the Tat activity on PMNL is mediated by its chemokine-like region and that PMNL recruitment by Tat is linked to angiogenesis.

Involvement of the IP-10 chemokine in sarcoid granulomatous reactions

The accumulation of T cells and monocytes at sites of ongoing inflammation represents the earliest step in the series of events that lead to granuloma formation in sarcoidosis. In this study, we evaluated the pulmonary production of IFN-inducible protein 10 (IP-10), a CXC chemokine that stimulates the directional migration of activated T cells. Striking levels of IP-10 were demonstrated in the bronchoalveolar lavage (BAL) fluid of 24 patients with pulmonary sarcoidosis and lymphocytic alveolitis, as compared with patients with inactive disease or control subjects. A positive correlation was demonstrated between IP-10 levels and the number of sarcoid CD45R0+/CD4+ cells in the BAL. Immunochemistry, performed with an anti-human IP-10 polyclonal Ab in lymph nodes displaying prominent sarcoid granulomas, showed that cells bearing IP-10 were mainly epithelioid cells and CD68+ macrophages located inside granulomatous areas. Macrophages recovered from the BAL of sarcoid patients stained positive for IP-10 protein. Furthermore, alveolar macrophages isolated from sarcoid patients with T cell alveolitis and cultured for 24 h in presence of IFN-gamma secreted definite levels of IP-10 capable of inducing T cell chemiotaxis. Interestingly, alveolar lymphocytes recovered from patients with active sarcoidosis were CD4+ T cells expressing Th1 cytokines (IL-2 and IFN-gamma) and high levels of CXCR3. Taken together, these data suggest the potential role of IP-10 in regulating the migration and activation of T cells toward sites of sarcoid inflammatory process and the consequent granuloma formation.

Pentoxifylline as a supportive agent in the treatment of cerebral malaria in children

In an open, randomized, controlled therapeutic trial, 56 children with cerebral malaria (CM) were randomly assigned to receive standard quinine regimen with or without pentoxifylline (10 mg/kg/day by continuous intravenous infusion). Pentoxifylline exerted an inhibitory effect on the synthesis of tumor necrosis factor (TNF), a possible mediator of CM. The 26 children who received pentoxifylline had significantly shorter comas than controls (median, 6 vs. 46 h; P < .001) Pentoxifylline recipients showed a trend toward a lower mortality, with a borderline significant difference (P = .055). The better outcome in the pentoxifylline group was associated with a decline in TNF serum levels on the third day of treatment in a few subjects that was not seen in controls. While alternative or concurrent mechanisms of action may be of some relevance, larger double-blind trials are needed to determine whether pentoxifylline has a therapeutic role in CM.

Tumour-infiltrating lymphocytes bear the 75 kDa tumour necrosis factor receptor

Tumour necrosis factor alpha (TNF-alpha) is a cytokine with a variety of immunological properties. The identification of two receptors for this molecule, i.e. the 75 kDa and the 55 kDa TNF receptors (TNF-R), recently clarified the mechanisms through which this cytokine provides its wide range of immunomodulatory activities. In this study we have investigated the expression and the functional properties of these receptors on tumour-infiltrating lymphocytes (TILs) recovered from 17 patients with solid cancers (melanoma, colorectal carcinoma and lung cancer). To this end, TIL lines and freshly isolated TILs were evaluated for (a) the expression and the functional role of TNF receptors following culture in the presence of interleukin 2 (IL-2) and (b) the production of TNF-alpha following culture with IL-2 and the role of this cytokine in IL-2-driven TIL proliferation. Flow cytometry analysis demonstrated that TILs bear the 75 kDa TNF-R. Moreover, TIL lines express detectable messages for TNF-alpha and release this cytokine. Functional in vitro studies have shown that anti-TNF-alpha, as well as anti-75 kDa TNF-R antibodies, are able to inhibit the IL-2-induced TIL proliferation. These data demonstrate that TILs are equipped with a fully functional TNF-R system and suggest a putative role for this receptor and its ligand in the activation and expression of TILs following immunotherapy with IL-2.

Childhood onset cyclic neutropenia: G-CSF therapy restores neutrophil count but does not influence superoxide anion and cytokine release by neutrophils

In this paper we describe the case of a 16-year-old boy with childhood onset cyclic neutropenia (CN) with a 21 d cycle who was successfully treated with recombinant granulocyte-colony stimulating factor (G-CSF). Cyclic therapy with G-CSF (5 micrograms/kg/d s.c. for 1 week every 21 d) maintained peripheral neutrophil count above the normal range, reduced the incidence of severe infections and significantly improved the patient's performance status throughout an 18-month follow-up. Phenotypic analysis of circulating lymphocytes demonstrated that G-CSF treatment does not modify the phenotypic profile of circulating B, T and NK cell populations. Circulating neutrophils released normal amounts of cytokines (including IL-1 beta, IL-8, TNF alpha) and superoxide anion during G-CSF therapy.

Alpha (p55) and beta (p75) chains of the interleukin-2 receptor are expressed by AML blasts

In the present study, we have investigated the leukemic cells obtained from 16 patients with acute myeloid leukemia (AML) at diagnosis for the membrane expression of p55 (alpha) and p75 (beta) interleukin-2 receptor (IL-2R) chains using specific monoclonal antibodies (mAbs), as well as for the presence of their transcripts using Northern blot analysis. In addition, immunoprecipitation of the p75 membrane molecule with TU27 and Mik-beta 1 mAbs was carried out in selected cases. The p75 IL-2R beta transcripts were detected in all cases, whereas the membrane p75 molecule was demonstrable by flow cytometry in three cases. However, data from the immunoprecipitation analysis suggest that the lack of the p75 IL-2R detection by flow cytometry might be caused by the low density of molecules per cell rather than the fact that the specific mRNA is not translated into the p75 surface molecule. In addition, a consistent membrane positivity with an anti-p55/CD25 mAb, present on fresh uncultured blasts in 37.5% of the cases, became detectable after short-term culture in 75% of cases. In each individual case, a strict correlation was found between membrane CD25 reactivity and the expression of p55 mRNA. Taken together, our data suggest that the expression of both alpha (p55) and beta (p75) IL-2R molecules is a common feature of leukemic cells in AML, and provide new arguments for reassessing the possible role of IL-2 in leukemic growth.

The CD4 molecule belongs to the phenotypic repertoire of most cases of acute myeloid leukemia

In the present study fresh leukemic cells obtained from 23 patients with acute myeloid leukemia (AML; FAB subtypes: three M1, five M2, two M3, five M4, eight M5) were investigated for the membrane expression of the CD4 molecule by cytofluorimetric analysis with an anti-CD4 monoclonal antibody (mAb). In 15 cases the presence of the CD4 mRNA was also investigated using Northern blot analysis. Membrane expression of the CD4 molecule was demonstrated in 19 out of 23 cases, and it was found to be weaker than in CD4+ lymphocytes and monocytes obtained from normal controls. Full-length CD4 mRNA was detected in 12 out of 15 (80%) cases, and AML cells positive for CD4 mRNA expression also expressed the CD4 antigen. Since the CD4 molecule expressed by T cells is associated with p56lck, a member of the src family of intracellular tyrosine kinases, we investigated whether the CD4 molecule expressed by myeloid blasts is also associated with a tyrosine kinase activity. In vitro kinase assays performed on anti-CD4 immunoprecipitates from lysates of myeloid leukemia cells from four CD4+ cases were negative for the presence of a tyrosine kinase activity. This finding was not due to the lack of expression of members of the src family since we were able to detect at least p60src and p59fyn in myeloid leukemia cells. According to our results, the CD4 molecule seems to belong to the phenotypic repertoire of most AML, irrespective of their FAB subtypes. However, in myeloid blasts this molecule is not associated with a tyrosine kinase activity as it occurs in T lymphocytes.

Role of tumor necrosis factor-alpha and its specific 55-Kd and 75-Kd receptors in patients with lymphoproliferative disease of granular lymphocytes

The role of tumor necrosis factor-alpha (TNF-alpha) in the development of in vitro proliferative and cytotoxic abilities of granular lymphocytes (GL) in patients with lymphoproliferative disease of GL (LDGL) has been investigated. To this aim, taking advantage of the recent generation of specific monoclonal antibodies (MoAbs) reacting with the p55 and p75 TNF receptors (TNF-R) (htr-9 and utr-1 MoAb, respectively), we evaluated the expression and the functional role of each TNF-R in freshly isolated highly purified GL from a series of 10 LDGL patients (six CD3+ T-lineage GL and four CD3- natural killer [NK]-lineage GL). The expression of TNF-alpha transcripts and the release of TNF-alpha in the culture medium at resting conditions and following cell activation were also studied. Our data indicate that at resting conditions both CD3+ and CD3- GL express only the p75 TNF-R. Accordingly, a specific inhibition of phycoerythrin (PE)-conjugated TNF-alpha binding was demonstrated by the anti-p75 TNF-R utr-1 MoAb, but not by the anti-p55 htr-9 MoAb. Following activation with interleukin-2 (IL-2), anti-CD3, or anti-CD16 MoAbs, an increased expression of the p75 TNF-R and a slight induction of the p55 TNF-R was observed. Weak expression of specific TNF-alpha transcripts was detected at resting conditions and on unstimulated cells, whereas both IL-2 or anti-CD3 MoAb induced TNF-alpha mRNA. Under these in vitro conditions, detectable amounts of this cytokine were demonstrated in the culture supernatant of GL. The cytotoxic and proliferating activities mediated by IL-2 or anti-CD3 MoAb were dampened by anti-TNF-alpha antibody, suggesting a role for endogenous TNF-alpha in these functions. Both utr-1 and htr-9 MoAbs showed a moderate inhibition of proliferative activity, whereas cytotoxicity was not reduced. Taken together, our results suggest that TNF-alpha plays a role in the mechanisms leading to CD3+ and CD3- GL in vitro activation in patients with LDGL.

Expression and functional role of the p75 interleukin 2 receptor chain on leukemic hairy cells

Hairy cell leukemia is a chronic lymphoproliferative disorder characterized by the expansion of neoplastic B-cells expressing the p55 chain of the interleukin 2 receptor (IL-2R) system that is recognized by anti-CD25 monoclonal antibodies (mAb) and binds interleukin 2 (IL-2) with low affinity. In the present study we investigated leukemic hairy cells (HC) for the presence of the p75 IL-2R chain which binds IL-2 with intermediate affinity and plays a crucial role in transducing the message to the cell. For this purpose, we tested highly enriched leukemic HC from six hairy cell leukemia patients for the presence of IL-2R transcripts and for the expression of the p55 and p75 IL-2R chains on their surface membrane by flow cytometry and immunoprecipitation analyses. The functional role of IL-2 in the regulation of HC proliferation was also investigated. Our results indicate that freshly isolated HC express detectable messages for both the p75 IL-2R and the p55 IL-2R. Flow cytometry analysis demonstrated detectable levels of p75 IL-2R on the HC from all patients tested. A mixture of two specific mAb was able to immunoprecipitate detectable amounts of p75 IL-2R from leukemic HC. When leukemic HC were cultured in the presence of several concentrations of IL-2 a low proliferative response was observed. Moreover, the IL-2-driven proliferation of HC was markedly inhibited by anti-p75 IL-2R mAb and to a lesser extent by anti-p55 IL-2R mAb. These findings provide direct evidence of the expression of different IL-2 receptors on leukemic HC and suggest that these molecules might play a role in leukemic cell growth.

Induction of expression of genes encoding components of the respiratory burst oxidase during differentiation of human myeloid cell lines induced by tumor necrosis factor and gamma-interferon

In HL-60 and ML-3 human myeloid cell lines, gamma-interferon (IFN-gamma) and/or tumor necrosis factor (TNF) induce synergistic accumulation of transcripts of the genes encoding the heavy chain (gp91-phox) of cytochrome b558 and the cytosolic factors p47-phox and p67-phox, components of the superoxide-generating NADPH oxidase system. The accumulation of transcripts for gp91-phox and p47-phox, as quantitated at the single-cell level by in situ hybridization, is extremely heterogeneous; however, when the cells are stimulated by IFN-gamma and TNF together, most or all the cells in the induced cultures express higher accumulation of gp91-phox and p47-phox transcripts than cells from uninduced culture. In situ hybridization was performed on cellular subsets separated by fluorescence-activated cell sorting on the basis of surface expression of differentiation antigens or respiratory burst activity. The accumulation of gp91-phox and p47-phox transcripts correlated positively with the expression of the CD14 and CD11b antigens, two markers expressed on mature myelomonocytic cells. Similarly, accumulation of the two transcripts correlated with respiratory burst activity in cells separated by fluorescence-activated cell sorting after being loaded with dichlorofluorescein diacetate and stimulated with 12-O-tetradecanoylphorbol-13-acetate. These results suggest that all the cells in the culture are induced to differentiate by TNF and IFN-gamma but that at the time of analysis there is heterogeneity in the level of differentiation and a proportion of cells is present that shows more mature characteristics with a coordinate expression of the various differentiation markers and functions.

Inhibition by verapamil of neutrophil responses to formylmethionylleucylphenylalanine and phorbol myristate acetate. Mechanisms involving Ca2+ changes, cyclic AMP and protein kinase C

Verapamil inhibits in human neutrophils the respiratory burst, the secretion and the change of transmembrane potential induced by formylmethionylleucylphenylalanine, a Ca2+-dependent stimulus, and by phorbol myristate acetate, a Ca2+-independent stimulus. Besides the blocking of Ca2+ channels, many mechanisms are responsible for the inhibition of neutrophil responses. In fact, verapamil (i) increases the intracellular cAMP concentration, potentiates the cAMP response induced by the chemotactic peptide and induces the appearance of a cAMP response also when the stimulant is phorbol myristate acetate; (ii) causes a decrease of Ca2+ association to cell membranes, so depleting the pools of exchangeable Ca2+ and depressing the 'Ca2+ response' in terms of rise in [Ca2+]i monitored with Quin 2 and of rapid mobilization from cell membranes monitored by chlorotetracycline fluorescence change; (iii) inhibits the Ca2+-activated phospholipid-dependent protein kinase C. The data, discussed in relation to the biochemical mechanisms of the stimulus-response coupling, are compatible with the hypothesis of an involvement of the activation of protein kinase C as key step in the sequence of transduction events for the induction of many neutrophil functions.