The use of temozolomide in recurrent malignant gliomas

Gliomas are the most common primary intracerebral tumours and over 60% of these are malignant. Standard treatment in the UK for patients with a good performance status consists of surgery and postoperative radiotherapy, however, recurrence is almost inevitable. Treatment of recurrent malignant gliomas (MG) is limited to further surgery, chemotherapy and novel biological therapies. The response rate to standard chemotherapy protocols for recurrent MG is less than 30%. Temozolomide (Temodar-US, Temodal-Rest of World) is an oral alkylating agent with a similar chemical structure to dacarbazine, and has recently been licensed in the UK for second line treatment of recurrent MG. Several phase II studies and one randomised trial suggest that Temozolomide improves time to progression and quality of life but not overall survival. The drug is well tolerated with dose limiting myelosuppression and thrombocytopenia occurring in less than 10% of patients at current dosage schedules. A randomised trial comparing Temozolomide with best first line adjuvant chemotherapy (PCV) is about to start recruiting patients. Further clinical studies investigating its role in neoadjuvant treatment or in combination with radiotherapy or other chemotherapeutic approaches are ongoing.

Pegylated liposomal doxorubicin (Caelyx) in recurrent ovarian cancer

Epithelial ovarian cancer (EOC) is the most common gynaecological malignancy in the Western world and a leading cause of death. Patients with relapsed EOC are incurable and therefore the toxicity of palliative chemotherapy and effects on health-related Quality of Life are important factors. Several newer cytotoxic agents have been used in these patients. Pegylated liposomal doxorubicin (Caelyx) has a different spectrum of activity from standard doxorubicin with response rates up to 25% in these patients and a low toxicity profile. In addition it is non cross resistant with platinum compounds. In a randomised phase III trial (n=474) of Caelyx versus Topotecan there were no significant differences in response rates, time to progression, overall survival or quality of life. Patients receiving Topotecan had more side effects requiring admission to hospital. Caelyx is a valuable therapy in platinum resistant patients with an efficacy equivalent to Topotecan but at a lower cost when side-effects and admission costs are included.

The evidence-based use of induction chemotherapy in breast cancer

The use of induction chemotherapy, also known as pre-operative or neoadjuvant chemotherapy has been studied in a number of randomised trials. Response rates are generally high, ranging from 70-90%, which allows for the downstaging of primary tumours and breast conservation surgery. Conserving surgery as opposed to mastectomy in this setting appears to be safe, effective and improves quality of life, although there is a suggestion of a small increase in local recurrence rate. Data from the randomised trials presented in this review shows that the use of induction chemotherapy neither prolongs nor decreases overall or disease free survival when compared with the same chemotherapy given in an adjuvant setting. There is a direct correlation between response of a primary breast tumour to induction chemotherapy and patient outcome, probably because this approximates the effect of induction chemotherapy on micrometastases which are present at presentation in many patients with apparently localised primary breast cancers. A pathological complete response after surgery is an excellent predictor of long term outcome, and is more likely to be seen in smaller tumours. Induction chemotherapy can be used as an in vivo measure of tumour response to treatment. This allows a further option of switching cytotoxic drugs in apparently resistant tumours.

Expression on human eosinophils of CD148: a membrane tyrosine phosphatase. Implications in the effector function of eosinophils

The role of protein tyrosine phosphatases (PTP) is crucial in regulating the phosphorylation status of cells. CD148 is a recently described membrane-type PTP. In this study, we have demonstrated that this molecule is expressed on human eosinophils and eosinophilic cell line EoL-3. Interestingly, our data also showed that this molecule acts as a transduction molecule on these cells. Thus, the crosslinking of CD148 was able to induce the degranulation and the induction of superoxide anion generation. By using specific inhibitor and by western blotting, we have shown that tyrosine kinase activation is involved in this transduction pathway. In addition, we have shown the presence of a serine/threonine kinase activity associated with CD148. In conclusion, the activation capacity of CD148 on eosinophils suggests a potential role of this molecule on inflammatory diseases, such as allergic and parasitic diseases, associated with eosinophilia.

Novel molecular mechanisms of dendritic cell-induced T cell activation

In this study we have re-examined the molecular mechanisms involved in activation of T cells by dendritic cells (DC). Human peripheral blood DC (PBDC) were derived by 2 h adhesion followed by 7 day culture in a combination of granulocyte macrophage colony stimulating factor and IL-4, and depletion of residual T and B cells. These PBDC were used to induce autologous T cell proliferation in a CD3-dependent response, and antibodies against CD11a/18 and CD86 were used as control inhibitors of accessory function. Antibodies against five of the cell surface molecules that we have recently identified on the surface of DC, CD13, CD87, CD98, CD147 and CD148, and an antibody which recognizes a molecule that has not as yet been identified, all inhibited the CD3-induced T cell proliferation. These findings were observed not only when antibodies were present throughout the culture, but also when they were prepulsed on to the surface of the DC, suggesting the inhibition was mediated via the antigen-presenting cells rather than the T cell. The same set of antibodies also inhibited an allospecific mixed lymphocyte reaction, confirming that the inhibitory effect was not dependent on the use of a CD3 antibody as the stimulating agent. All the antibodies of known specificity inhibited both CD4 and CD8 T cells equally. Unlike CD87, CD98 and CD147 antibodies, which inhibited activation of both CD45RA (naive) T cells and CD45RO (memory) T cells, CD13 and CD148 appeared to be involved in activation of naive cells only. The molecules identified in this study have not previously been demonstrated to play a role as accessory molecules on DC, the cells that are pivotal for immune induction. Therefore they may provide new potential targets for modulation of the immune response at the APC level.

Expression of the membrane protein tyrosine phosphatase CD148 in human tissues

CD148, a receptor-like protein tyrosine phosphatase also known as HPTP-eta/DEP-1, is involved in signal transduction in leucocytes and is thought to contribute to mechanisms of cellular differentiation. We have investigated the in situ expression of CD148 in various fresh-frozen tissues by immunohistology and analyzed its expression on subpopulations of activated peripheral blood leucocytes by flow cytometry. In lymphoid organs, CD148 was found to be widely expressed on B and T cells, granulocytes, macrophages, certain dendritic cells as well as mature thymocytes. The cellular level of CD148 was increased after in vitro activation of peripheral blood leucocytes. Comparative analysis of tissue samples from normal gut and from patients with active Crohn's disease showed that leucocytes expressing CD148 are significantly upregulated in inflamed tissues and that a subset of these cells co-express the activation marker CD25. In non-lymphoid tissues, CD148 was found to be present on many epithelial cell types with glandular and/or endocrine differentiation as well as on fibrocytes, melanocytes and Schwann cells. CD148 expression was maintained also in malignant counterparts of such tissues. However, a marked loss of CD148 immunoreactivity was apparent in some of the investigated high-grade carcinomas. In summary, our results confirm a role of CD148 as a leucocyte activation marker. Among non-hematopoietic cells, CD148 is expressed by characteristic types of epithelial and non-epithelial cells. Downregulation of CD148 might promote dedifferentiation and autonomous growth of such cells in malignant tumors.

Upregulated expression of VLA proteins and CD29 in peripheral blood lymphocytes of chronic alcoholics without ethanol-related diseases

To analyze adhesion molecule expression on peripheral blood mononuclear cells (PBMCs) and on different lymphocyte subpopulations (CD2+, CD8+, CD19+, and CD56+ subsets) in chronic alcoholism, 30 well-nourished chronic alcoholics without ethanol-related diseases and 30 matched controls were included in the study. Adhesion molecules that mediate adhesion to other cells and to extracellular matrix proteins, and whose cellular expression is modified during lymphocyte activation, were selected for study. A detailed clinical evaluation, laboratory analysis, nutritional assessment, and study of adhesion molecule expression was performed. A significant higher expression of CD29 (beta1-integrin) (p = 0.001), VLA-3 (p = 0.002), VLA-4 (p = 0.03), and VLA-5 (p = 0.001) were observed on PBMCs of chronic alcoholics, compared with control subjects, whereas no changes were observed in CD18 (beta2-integrin) and CD50 (ICAM-3) expression. The upregulation of CD29 and VLA proteins only affected T lymphocytes (CD2+/CD8+/CD4+ cells). These data confirm that T cells of chronic alcoholics are basally activated and that changes in adhesion molecule expression on PBMCs may be responsible of disturbances of adhesion processes in chronic alcoholics without ethanol-related diseases.

Nitric oxide production by pig endothelial cells in response to human-derived injury

BACKGROUND

The hyperacute rejection induced by natural antibodies is the first barrier to the success of pig to human organ xenotransplantation. When this barrier is overcome, an infiltrate of mainly monocytes and natural killer cells can be observed. Nitric oxide (NO) has been described to be involved in allo- and xenorejection, and to participate in the regulation of monocyte infiltration in other models.

METHODS

We have studied the capacity of human monocytes and natural antibodies to induce the production of NO by pig endothelial cells, by measuring NO2, a stable end product of NO.

RESULTS

Human monocytes can induce HuProVim (HUP), a pig endothelial line, and "in situ, ex vivo" pig endothelial cells to produce NO2. This NO2 production was inhibited by NG-nitro-L-arginine-methylester and NG-monomethyl-L-arginine, inhibitors of NO production. This induction can be observed even if cells are separated by a semipermeable membrane, which indicates that it is a result of soluble factors. Activated cells continue producing NO after triggering for 1 hr. No NO2 production was observed after activation of HUP cells with recombinant human interleukin (IL)-1alpha, IL-1beta, IL-6, IL-10, transforming growth factor-beta1, IL-2, IL-4, interferon-gamma, or recombinant human tumor necrosis factor-alpha (rhTNF-alpha) alone. Only the combination of rhTNF-alpha+rIL-1alpha or rIL-1beta, and rhTNF-alpha+rIL-1alpha+IFN-gamma induces some NO production. Human natural anti-pig antibodies, which had been described to induce cytoskeleton changes on endothelial cells, do not induce NO production.

CONCLUSIONS

Our data show that human monocytes induce the production of NO by pig endothelial cells. The inducing signal is soluble and cannot be provided by human anti-pig natural antibodies.

Elevated soluble CD27 levels in serum of patients with systemic lupus erythematosus

The CD27 belongs to the NGF-R, a family of type I transmembrane receptors present in most T cells. The soluble form of CD27 can be found in body fluids, and elevation of serum levels is observed in T cell activation. Preliminary studies indicate that measurement of sCD27 levels might be of use in the evaluation of immune responses in vivo. Systemic lupus erythematosus (SLE) is a disease of unknown etiology. T cells from SLE patients have impaired responsiveness to various kinds of stimuli. However, the precise localization of the defect in the activation of SLE remains unclear. In this study we have analyzed the sCD27 serum levels in a SLE population and in a healthy group control. Seventy patients with SLE were prospectively studied. As controls, 20 healthy volunteer blood donors, matched by sex and age, were studied. We developed an enzyme-linked immunosorbent assay (ELISA) to measure sCD27. The mean level (+/-SD) of sCD27 was higher in the SLE patients (48.29 +/- 23.86 u) than that in the control group (36.13 +/- 7.48 u) (P = 0.02). In addition, patients with active SLE revealed higher serum concentration of sCD27 (58.20 +/- 31.06 u) than that of patients in remission (42.77 +/- 16.71 u) (P < 0.01). We found a positive correlation among sCD27 and sCD25 serum levels in SLE patients (r = 0.30, P = 0.01). No significant relation was found for other clinical symptoms or immunological parameters. In conclusion, sCD27 serum levels were increased in SLE patients and this increase was associated with the activity of the disease. Our data are consistent with the hypothesis that the CD27 antigen may constitute a marker of disease activity.

Cytokine gene expression and release from epithelial cells. A comparison study between healthy nasal mucosa and nasal polyps

BACKGROUND

Epithelial cells release cytokines and they probably contribute to chronic inflammation detected in bronchial asthma, rhinitis and nasal polyposis.

OBJECTIVES

To investigate the effect of cultures on cytokine gene expression to compare epithelial cell cytokine release by both healthy nasal nucosa (HNM) and nasal polyps (NP), and the modulation by dexamethasone and to investigate which cytokines may promote eosinophil survival.

METHODS

Epithelials cells were cultured to confluence, human epithelial cell conditioned media generated with or without dexamethasone, and supernatants measured by ELISA. Cytokine gene expression was investigated by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Fresh epithelial cells only expressed mRNA for intesleukin-8 (IL-8) and granulocyte macrophage-colony stimulating factor (GM-CSF) while cultured cells expressed mRNA for IL-1 beta, IL-6, IL-8, tumour necrosis factor-alpha (TNF alpha) and GM-CSF. Epithelial cells from NP significantly (P < 0.05) released more IL-8 (25431 +/- 3163 pg/mL), and GM-CSF (1229 +/- 391 pg/mL) than those from HNM (18604 +/- 1723 pg/mL for IL-8; and 611 +/- 98 pg/mL for GM-CSF). Dexamethasone 10 microM inhibited the release of all cytokines, this effect being similar (40-50%) in both HNM and NP, except for IL-6 which was higher in HNM. Eosinophil survival induced by epithelial cell secretions from both HNM and NP was strongly blocked by GM-CSF antibody while it was partially blocked by antibodies to TNF alpha and IL-8.

CONCLUSIONS

These findings suggest that although epithelial cell culture procedures may upregulate cytokine gene expression, nasal polyps may represent a more active inflammatory tissue by releasing more cytokines than healthy nasal mucosa this release being inhibited by steroids; and that, in addition to GM-CSF, other cytokines such as TNF alpha and IL-8, may also be involved in the promotion of eosinophil survival.

Changes in idiotypic predominance in the anti-arsonate response by priming with anti-idiotypic antibodies

The predominant selection of CRI-A-bearing antibodies during the anti-arsonate (ARS) response of A/J mice has been used as a model to analyse the mechanism involved in the process of clonal selection and establishment of predominance. In order to assess the importance of the affinity and adaptability of CRI-A clones in this process, we tested the capability of a minor recurrent idiotype (id-1A3), present in a CRI-Aanti-ARS monoclonal antibody (65-1A3), to develop a normal anti-ARS response. Our results show that the id-1A3 predominance, established by anti-id-1A3 administration was stable during the primary and secondary anti-ARS response and that this predominance occurred concomitantly with low levels of CRI-A. Thus, a change in the idiotype predominance was achieved. In spite of the high levels of id-1A3, the anti-ARS antibody concentration, the affinity values, and the kinetics of the immune response were similar to those of the control group. All these results show that CRI-A clones are not essential in the normal development of the anti-ARS antibody response of A/J mice, and suggest that factors other than affinity could be involved in the establishment of the CRI-A predominance.

Direct measurement of antibody affinity distribution by hapten-inhibition enzyme immunoassay

A rapid, simple and reliable technique for determining the affinities of antibody subpopulations in a complex mixture is described. The principle of this method is that antigen conc can be represented as the amount of antigen immobilized on the polystyrene surface of a microwell containing a fixed vol of diluted antibody. Thus, by measuring the proportion of antibody bound to different wells coated with varying amounts of antigen, it is a straightforward matter to calculate an affinity distribution. We have verified that: (1) the amount of antigen bound to a polystyrene plate is proportional to the concn of antigen used for sensitization and follows a typical saturation curve; (2) the antibodies bound to plates sensitized with low concns of antigen are of higher affinity than those bound to plates sensitized with high concns of antigen; (3) an apparent affinity constant (aK) is defined as the reciprocal concn of free hapten required for 50% inhibition of antibody binding to immobilized antigen; (4) the aK determined by this method is in close agreement with the intrinsic affinity constant (K) measured by fluorescence quenching or the Farr assay; and (5) that during the course of immunization in vivo there is a clear shift to higher-affinity antibody subpopulations.