The X1 box of HLA-G promoter is a target site for RFX and Sp1 factors

HLA-G gene regulation was investigated with regards to homologies among the pathways regulating both classical MHC class I and MHC class II gene expression. They include four conserved cis-acting regulatory elements located in the proximal promoter region referred to as the W/S/Z box, the X box that is comprised of the X1 and X2 halves, and the Y box with an inverted CCAAT site. The X1 box is the binding site for the ubiquitous RFX complex consisting of three subunits; the X2 box is bound by the X2BP/ATF/CREB family factors. The basic S-X-Y regulatory module interacts with CIITA, which is expressed constitutively in APCs, but may be inducible in others cell types by IFN-gamma. Within HLA-G gene promoter the only conserved motifs are S and X1 boxes. We thus investigated the binding capacity of the HLA-G X box in comparison to that of HLA-DRA and HLA-E. We demonstrate that X2 box mutations in HLA-G promoter affect the binding of ATF/CREB family factors and may privilege the X2 box to access by other shared factors. The X1 box is the target for RFX complex and an additional factor we identified as Sp1. We propose that the X region in the HLA-G gene promoter might participate to the combination of factors which play a role in HLA-G gene activation.

Modulation of HLA-G expression in human thymic and amniotic epithelial cells

Expression of the nonclassical HLA class I antigen, HLA-G, is tightly regulated. HLA-G physiologic expression is mostly restricted to some placental and thymic cell types. Only few established cell lines express HLA-G in vitro. Cytokine-induced expression of HLA-G is hardly observed and also depends on the cell lineage. We assessed expression and cytokine regulation of HLA-G in primary cultures derived from human thymus and amnion epithelial cells, which also express HLA-G in vivo. We show that HLA-G cell surface expression is maintained, but decreases gradually, in primary cultures derived from human thymus and amnion epithelial cells. We also show that IFN-gamma re-induces HLA-G cell surface expression and upregulates classical class I gene expression in both primary cultures and in a thymus derived cell line. We further show that IFN-gamma also upregulates levels of HLA-G transcripts in TEC primary cultures. This study provides evidence that IFN-gamma induction of HLA-G expression occurs in the human amnion and the thymus, and is mediated at the transcriptional level in these tissues. These results also suggest a role for the microenvironment in regulating HLA-G in vivo gene expression in the thymus and amnion membrane.

Analysis of the role of HLA-G in preeclampsia

Preeclampsia (PE) is a multisystem disorder of human pregnancy, occurring in 5%-10% of all population births and represents the leading cause of both fetal and maternal morbidity and mortality in pregnancy. Although the disorder only becomes clinically apparent late in pregnancy, the underlying pathology indicates that invasion of fetal trophoblasts into maternal spiral arteries during early pregnancy is shallow or absent in PE. A large number of epidemiologic studies have been carried out and they demonstrate that the disorder is highly heritable and occurs with a high incidence in all populations. Studies have shown that PE is largely under genetic control, but the mode of its inheritance remains unclear. Genetic studies have been carried out using both large scale linkage analysis and candidate gene approaches; however, the genetic mechanisms underlying the disorder have yet to be determined. We focus on the potential role of HLA-G, a nonclassical class I HLA located on chromosome 6, which appears to be a key component in trophoblast invasion. We examine the hypothesis that HLA-G may have a key role in both genetic susceptibility to, and pathogenesis of, PE.

HLA-G, -E, -F preworkshop: tools and protocols for analysis of non-classical class I genes transcription and protein expression

Non-classical MHC class I HLA-E, -F, and -G molecules differ from classical class I histocompatibility antigens by specific patterns of transcription, protein expression, and immunological functions. Restriction of the expression pattern of these non-classical antigens may play a key role in modulation of immune responses during pregnancy and diseases but remains to be additionally defined. A specific component of the second International Conference on HLA-G and the 13th HLA-G Histocompatibility Workshop will be dedicated to the analysis of transcription and expression of non-classical class I genes in normal and pathological tissues. In a first step, referred to as the preworkshop, we here report the analysis and conclusions of a working group which was constituted to gather and validate optimal reagents and protocols allowing RT-PCR analysis of HLA-E, -F, -G transcript levels and flow cytometry and immunochemistry analysis of HLA-G expression in cells and tissues. As a result of this work, use of specific primers and probes detecting alternative transcripts of HLA-E, -F, and G have been validated in transfected cells expressing differential pattern of HLA class I antigens. Analysis of the specificity and affinity of collected antibodies has allowed definition of reagents to be proposed for immunochemistry and flow cytometry analysis of HLA-G expression in normal and pathological tissues during the workshop. This work has allowed constitution of an extended workshop group which is now initiating analysis of non-classical class I transcription and expression in various cells and tissues, a collective contribution that will additionally refine our view of the expression of these antigens in normal and pathological situations.

Limb salvage for proximal tibial tumours using a modular prosthesis

We report early results after the resection of proximal tibial tumours followed by reconstruction using a modular prosthesis. The indication for wide resection was a malignant tumour in 13 patients, and a neglected giant cell tumour in 2. There were no mechanical failures during an average follow-up of 3.5 years. However, there were 5 peroneal nerve palsies, 1 complete sciatic nerve palsy, 1 vascular injury leading to an above knee amputation, and 2 deep prosthetic infections. There were 2 superficial skin necroses and 1 fracture proximal to the femoral prosthetic component. The mean post-operative Musculo-Skeletal Tumour Society (MSTS) score in 12 patients who still had their prosthesis in situ was 18.3 out of a possible total of 30 (range: 10-28). Limb salvage surgery in the proximal tibia has a high early complication rate even with the use of modern implants and improved techniques.

Lack of benefit of CD34+ cell selected over non-selected peripheral blood stem cell transplantation in multiple myeloma: results of a single center study

In order to determine the clinical impact of CD34+ cell selected autologous transplantation in multiple myeloma (MM), we have performed a retrospective case-controlled analysis comparing 21 MM patients receiving high-dose melphalan and autologous transplantation with CD34+ peripheral blood stem cells (PBSC) as front-line therapy to 21 control patients receiving unselected products. Case matching was performed using the following criteria: age and beta2-microglobulin at diagnosis and disease status at the time of transplantation. Both cohorts were homogeneous in term of induction treatment and conditioning regimen. Patients were collected for CD34+ selection after priming with G-CSF alone. Significantly fewer CD34+ cells/kg were infused to patients in the selected group as compared to patients in the control group: 2.2 (range 0.5-14.3) vs 9.4 (range 1.1-15) (P < 0.001). The median time to neutrophil recovery > or =0.05 x 10(9)/l was 10 days for the CD34+ group and 9.5 days for the control group (P = 0.357). The median time to platelet recovery > or = 20 x 10(9)/l was 9 days for the CD34+ group and 4.5 days for the control group (P = 0.005). Response rates were comparable in both groups (85.7% in the CD34+ group vs 90.4% in the control group). At 3 years, event-free survival (32% in the CD34+ group vs 39% in the control group) and overall survival (85% in the CD34+ group vs 79% in the control group) were not significantly different. Finally, use of unselected products dramatically reduced the cost of the transplantation procedure. This study shows that CD34+ cell selected autologous transplantation is more expensive than transplantation with unselected products and does not improve the clinical outcome of patients with MM.

Human herpesvirus 6 infection after autologous or allogeneic stem cell transplantation: a single-center prospective longitudinal study of 92 patients

To determine the incidence and clinical relevance of active human herpesvirus 6 (HHV-6) infection, 92 consecutive unselected recipients of autologous or allogeneic stem cell grafts were investigated in a prospective longitudinal study. Active infection was assessed by the presence of viral deoxyribonucleic acid (DNA) in 846 peripheral blood mononuclear cell specimens and 115 plasma specimens, by means of a specially developed polymerase chain reaction designed to avoid detection of latent genome. The incidence of HHV-6 infection observed was 42.5%, irrespective of the type or source of graft, and infection was significantly associated with partial (P=.002) or total myelosuppression (P=.01) and fever (P<. 000001). Infusion of bone marrow as the source of graft, reactivation occurring before platelet or neutrophil engraftment, and presence of HHV-6 DNA in plasma were identified as risk factors for symptomatic HHV-6 infection (P<.002).

Reactive plasmacytoses in multiple myeloma during hematopoietic recovery with G- or GM-CSF

We report on three cases of reactive plasmacytoses (RP) in the course of multiple myeloma (MM). The three patients achieved complete remission following high dose melphalan and peripheral blood stem cell transplantation. These transient plasmacytoses had all the characteristics of RP, i.e. expansion of highly proliferative polyclonal plasma cells (PC) with a normal phenotype and genotype and corresponding to expansion of both PC progenitors (plasmablasts) and PC precursors (early plasma cells). These cells were easily distinguished from malignant PC of the corresponding patients evaluated at diagnosis, especially by their phenotypic and genotypic features.

Salvage extended-field irradiation in follicular non-Hodgkin's lymphoma after failure of chemotherapy

PURPOSE

To evaluate the efficacy of total abdominopelvic (TAI) and total body irradiation (TBI) in heavily pretreated follicular non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

From 1983 to 1998, 34 patients received TAI (n = 22) or TBI (n = 12). All had Stage III or IV, Class B, C, D NHL in the working formulation and failed after receiving 1-5 regimens of chemotherapy. TAI was given at 20 Gy over a 3-week period. TBI was delivered in two successive half-body irradiations of 15 Gy over a 2-week period with a 4-week interval between each.

RESULTS

Mean follow-up from TAI or TBI was 120 months (range, 6-180). Seventy-six percent of patients achieved complete response and 24% partial response. Median survival was 62 months, 5-year and 10-year overall survival was 59% and 41%, and disease-free survival was 56% and 30%, respectively. Grade III or IV toxicity was gastrointestinal in 38% of patients and hematologic in 30%. No toxic death or delayed complications were observed.

CONCLUSION

Extended-field irradiation is feasible and efficient after failure of chemotherapy in follicular NHL.

A combination of anti-interleukin 6 murine monoclonal antibody with dexamethasone and high-dose melphalan induces high complete response rates in advanced multiple myeloma

To improve the complete response (CR) rate in advanced multiple myeloma (MM) without increasing the toxicity of high-dose therapy, we have used a new conditioning regimen. A combination of BE-8 [an anti-interleukin 6 (IL-6) murine monoclonal antibody] and dexamethasone followed by high-dose melphalan (220 mg/m2) and autologous stem cell transplantation was used to treat a series of 16 patients with advanced multiple myeloma. A strong inhibition of IL-6 activity evaluated by quantification of C-reactive protein was observed in all patients and was correlated with the high CR rate achieved with this combination therapy.

Recognition and cleavage of DNA by rebeccamycin- or benzopyridoquinoxaline conjugated of triple helix-forming oligonucleotides

Indolocarbazole and benzopyridoquinoxaline derivatives have been shown to have anti-tumor activity and to stimulate DNA topoisomerase I-mediated cleavage. Two indolocarbazole compounds (R-6 and R-95) and one benzopyridoquinoxaline derivative (BPQ(1256)) were covalently attached to the 3'-end of a 16mer triple helix-forming oligonucleotide (TFO). These conjugates bind to DNA with a higher affinity than the unsubstituted oligonucleotides. Furthermore, they induce topoisomerase I-mediated and triplex-directed DNA cleavage in a sequence-specific manner.

Fluorescence in situ hybridization on peripheral-blood specimens is a reliable method to evaluate cytogenetic response in chronic myeloid leukemia

PURPOSE

To evaluate the usefulness of fluorescence in situ hybridization (FISH) on peripheral-blood specimens to evaluate the cytogenetic response to treatment in patients with chronic myeloid leukemia (CML).

PATIENTS AND METHODS

In a first attempt, we analyzed 62 bone marrow specimens using interphase FISH and compared the results with those of conventional cytogenetics. In a second step, we analyzed 60 paired sets of bone marrow and peripheral-blood specimens with interphase FISH.

RESULTS

The results of interphase FISH agreed with conventional cytogenetics on bone marrow for most patients, and only minor differences were found (r =.98). The comparison of interphase FISH on bone marrow versus peripheral-blood specimens showed a strong correlation between these two specimen sources (r =.97).

CONCLUSION

Our results confirmed that FISH is a sensitive technique for the evaluation of response to treatment in patients with CML. Moreover, our study suggests that follow-up of cytogenetic response to therapy can be evaluated on peripheral-blood specimens, thus enabling an easier and more frequent evaluation of patients. The next step will be to evaluate this technique in a large prospective trial to define the prognostic value of complete remissions evaluated by FISH.

Aging, serum estradiol levels, and pregnancy differentially affect vascular reactivity of the rat uterine artery

OBJECTIVES

To investigate the effects of aging, ovarian ablation, and pregnancy on vascular reactivity of the rat uterine artery.

METHODS

Segments of uterine artery from 3-month-old pregnant and nonpregnant Wistar rats and from aged and ovariectomized animals, both 9 months of age, were exposed in vitro to vasoactive mediators. Absolute contractile force as well as endothelium-dependent and -independent vascular reactivity were determined. Isometric tension was recorded using a modified Mulvany myograph system. Results were compared with analysis of variance and Bonferroni-Dunn post hoc analysis and correlated with serum estradiol levels.

RESULTS

Aging up to 9 months decreased absolute tension of uterine arteries in vitro elicited by KCl (P < .0001), while not affecting receptor-operated responses to norepinephrine, endothelin-1, and angiotensin II. After ovarian ablation maximal contraction to norepinephrine was selectively reduced in the aged animal (P = .0053). Pregnancy increased absolute tension to KCl (P < .0001), norepinephrine (P < .008), and endothelin-1 (P = .0003), whereas relative contractile force (percentage of KCl) induced by norepinephrine and endothelin-1 remained unchanged and that induced by angiotension II decreased (P = .0001) in pregnant animals. In addition, pregnancy increased sensitivity to the endothelium-dependent vasodilator acetylcholine (P = .0022) but decreased that to the endothelium-independent vasodilator sodium nitroprusside (P = .0062). Endothelium-dependent relaxation correlated with serum estrogen levels remained unchanged in 9-month-old Wistar rats, which physiologically exhibited high serum estrogen concentrations but was impaired with regard to both maximum relaxation (P < .0001) and sensitivity in aged rats (P = .0007) after ovariectomy.

CONCLUSIONS

Vascular contractility is impaired in the uterine artery of the aged rat as evidenced by reduced responses to KCl, whereas responses to receptor-operated agonists remain unchanged. Functional ovaries are essential to preserve endothelium-dependent relaxation in aging animals. During pregnancy, contractile machinery and endothelium-dependent relaxation are enhanced. In contrast, contractions to angiotensin II and endothelium-independent relaxation to sodium nitroprusside are reduced in late pregnancy. These changes in reactivity of the uterine artery may be important for the regulation of blood flow in the uterus according to physiologic needs.

Invasive aspergillosis as an opportunistic infection in nonallografted patients with multiple myeloma: a European Organization for Research and Treatment of Cancer/ Invasive Fungal Infections Cooperative Group and the Intergroupe Français du Myélome

We report the occurrence of invasive aspergillosis (IA) in nonallografted patients with multiple myeloma (MM) who were treated at hematology or oncology centers in Europe during 1984-1996. Thirty-one cases met the criteria for definitive (21 [68%]) or probable (10 [32%]) IA. Of these cases, 23 (74%) were reported during 1992-1996. Twenty-nine cases (94%) occurred in patients with Durie-Salmon stage 3 MM, and 2 (6%) occurred in patients with Durie-Salmon stage 2 MM. The median time between MM and IA diagnoses was 8 months (range, 1-75 months). Sixteen patients (51%) had a neutrophil count </=500/mm3 for a median duration of 19 days (range, 10-37 days). Fourteen patients (45%) had recently received corticosteroid therapy, and 11 (36%), high doses of melphalan. Twenty-eight patients had primary pulmonary IA, and 3 had primary sinus IA. Forty-five percent of patients were considered to have died of IA. IA occurs as a potentially lethal opportunistic infection in intensively treated nonallografted patients with myeloma.

One of the origins of plasma membrane phosphatidylserine in plant cells is a local synthesis by a serine exchange activity

In plant cells, as in animal cells, the endoplasmic reticulum (ER) is considered to be the major site of phospholipid synthesis, and it has been shown that phosphatidylserine (PS) reaches the plasma membrane via the vesicular ER-Golgi-plasma membrane pathway in leek cells. However, it has never been determined whether the plasma membrane of leek cells is able to synthesize PS. We have analyzed the distribution of PS synthesizing enzymes along the vesicular pathway. In ER, Golgi and plasma membrane fractions isolated from leek cells, we have measured the activity of the two biosynthetic pathways leading to the synthesis of PS, i.e. serine exchange and CTP cytidylyltransferase plus PS synthase. We have found a high serine exchange activity in the plasma membrane fraction, and then determined that this membrane is able to synthesize both long chain fatty acid- and very long chain fatty acid-containing PS. Therefore, the PS in the plasma membrane of leek cells has two different origins: the intracellular vesicular pathway from the ER and a local synthesis in the plasma membrane.

Autologous stem cell transplantation for AL amyloidosis: a standard therapy?

Autologous stem cell transplantation (ASCT) is a new treatment option in patients with systemic AL amyloidosis (AL). The purpose of this review is to summarize the clinical experience of ASCT for AL, and to discuss the feasibility and the future developments of this new approach.

Mcl-1 and Bcl-xL are co-regulated by IL-6 in human myeloma cells

Multiple myeloma (MM) is a slowly proliferative malignancy in which malignant plasma cells accumulate within the bone marrow. The expression of several anti-apoptotic proteins was evaluated by immunoblotting in human myeloma cell lines and in highly purified native myeloma cells. Expression of Bcl-xL, Mcl-1 and Bcl-2 was found in most of the samples; expression of Bcl-xL and Mcl-1 seemed to be related on myeloma cells. In a system of apoptosis by growth factor deprivation on myeloma cells, we showed that the effect of Bcl-2 seemed minimal whereas Mcl-1 and Bcl-xL were tightly regulated by interleukin (IL)-6. These findings underline the important role of Mcl-1 and Bcl-xL instead of Bcl-2 in IL-6-induced survival of myeloma cells.

Radioimmunotherapy of small cell lung carcinoma with the two-step method using a bispecific anti-carcinoembryonic antigen/anti-diethylenetriaminepentaacetic acid (DTPA) antibody and iodine-131 Di-DTPA hapten: results of a phase I/II trial

As small cell lung carcinoma (SCLC) is frequently a widespread disease at diagnosis, highly radiosensitive and often only partially responsive to chemotherapy, radioimmunotherapy (RIT) would appear to be a promising technique for treatment. We report the preliminary results of a Phase I/II trial of RIT in SCLC using a two-step method and a myeloablative protocol with circulating stem cells transplantation. Fourteen patients with proved SCLC relapse after chemotherapy were treated with RIT. They were first injected i.v. with a bispecific (anti-carcinoembryonic antigen/anti-diethylenetriaminepentaacetic acid) monoclonal antibody (20-80 mg in 100 ml of saline solution) and then 4 days later with di-(In-diethylenetriaminepentaacetic acid)-tyrosyl-lysine hapten labeled with 1.48-6.66 GBq (40-180 mCi) of I-131 and diluted in 100 ml of saline solution. In patients receiving 150 mCi or more, circulating stem cells were harvested before treatment and reinfused 10-15 days later. Treatment response was evaluated by CT and biochemical data during the month before and 1, 3, 6, and 12 months after treatment. All patients received the scheduled dose without immediate adverse reactions to bispecific antibody or 1-131 hapten. Toxicity was mainly hematological, with two cases of grade 2 leukopenia and three cases of grade 3 or 4 thrombopenia. Body scanning 8 days after injection of the radiolabeled hapten generally showed good uptake at the tumor sites. Estimated tumor dose was 2.6-32.2 cGy/mCi. Among the 12 patients evaluated to date, we have observed 9 progressions, 2 partial responses (one almost complete for 3 months), and 1 stabilization of more than 24 months. Efficiency and toxicity were dose-related. The maximal tolerable dose without hematological rescue was 150 mCi. These preliminary results are encouraging, and dose escalation is currently continuing to reach 300 mCi. RIT should prove to be an interesting therapeutic method for SCLC, although repeated injections and hematological rescue will probably be required, as well as combination with other treatment modalities.

Apoptosis during regression of cardiac hypertrophy in spontaneously hypertensive rats. Temporal regulation and spatial heterogeneity

We previously reported that increased apoptosis participates in the regression of aortic hypertrophy in spontaneously hypertensive rats. To further document the potential role of apoptosis in cardiovascular therapy, we examined apoptosis during regression of hypertrophy in the heart of spontaneously hypertensive rats receiving the antihypertensive drug enalapril (30 mg. kg(-1). d(-1)), losartan (30 mg. kg(-1). d(-1)), nifedipine (35 mg. kg(-1). d(-1)), hydralazine (40 mg. kg(-1). d(-1)), propranolol (50 mg. kg(-1). d(-1)), or hydrochlorothiazide (75 mg. kg(-1). d(-1)) for 1 to 4 weeks, starting at 10 to 11 weeks of age. Systolic blood pressure and heart rate were measured by the tail-cuff method. Markers of apoptosis included oligonucleosomal DNA fragmentation in extracted cardiac DNA or in situ in ventricular cross sections labeled with terminal deoxynucleotidyl transferase. Cardiac DNA synthesis was evaluated by [(3)H]-thymidine incorporation in vivo. All drugs reduced cardiac workload, defined as the product of blood pressure and heart rate, by >20% at 4 weeks. However, only nifedipine, enalapril, losartan, and propranolol reduced cardiac mass (>19%) within 4 weeks. Regression of cardiac hypertrophy was accompanied by a 50% to 300% increase in DNA fragmentation and a >20% reduction in DNA synthesis, resulting in a >20% reduction in cardiac DNA content after 4 weeks. Apoptosis induction occurred early and was transient within 4 weeks of nifedipine, enalapril, or losartan administration. With all regression-inducing drugs, the increase in DNA fragmentation occurred mainly in the subepicardium. Thus, transient induction of apoptosis in the subepicardium appears to be a characteristic feature of the early response to drug-induced regression of cardiac hypertrophy in spontaneously hypertensive rats.

[Role of endothelin in the hypertrophic remodeling of small arteries induced by exogenous norepinephrine]

In a subset of hypertensive patients, activity of the sympathetic nervous system (SNS) is enhanced. Hypertension is also associated with an adaptative process where small arteries (lumen < 300 microns) are subjected to structural changes (eutrophic or hypertrophic remodeling). Since, it has been shown that norepinephrine (NE) can induced proliferation of vascular smooth muscle cells, the purpose of the present study was to determine the effect of a chronic treatment with NE, mimicking hyperactivity of SNS, on small artery structure. The role of endothelin (ET) in the process was also evaluated. To achieve these goals, control rats were compared with rats receiving NE 2.5 micrograms/kg/min alone or in combination with LU135252 30 mg/kg/d (ET-receptor antagonist, affinity ETA/ETB approximately equal to 100) for 2 weeks. Blood pressure was measured intra-arterially in conscious rats prior to sacrifice. Geometric parameters of the basilar artery were determined in pressurized and perfused conditions with calcium free Krebs solution. Plasma NE and arterial mesenteric ET levels were determined by HPLC and RIA respectively. Blood pressured was not altered following exogenous administration of NE for 2 weeks. However, media thickness increased while the lumen diameter was reduced at the level of the basilar artery, leading to elevated media:lumen ratio (p < 0.05). This morphological alteration was associated with a significant augmentation of the basilar artery cross-sectional area (CSA). Co-administration of LU135252 with NE prevented partially the increase of M/L while the elevation of CSA was completely blunted. Plasma levels of NE were significantly and similarly elevated in groups receiving NE but, interestingly, mesenteric ET levels were not modified by any treatment. These results suggest that chronic NE administration induced an hypertrophic inward remodeling of small arteries independently from blood pressure, which required the participation of ET as an obligatory intermediate. Furthermore, the local production of ET is probably enhanced transiently in the first days of NE administration and come back to control level at 2 weeks. Thus, early therapy initiation with an ET-receptor antagonist prevents vascular remodeling in conditions of SNS hyperactivity, which may contribute to lower risks of end-organ damage.

Immunocytochemistry of lipids: chemical fixatives have dramatic effects on the preservation of tissue lipids

We report here the effects of chemical fixatives on lipids studied under conditions simulating the immunogold labelling of phosphatidylserine. Using anti-phosphatidylserine antibodies, it is shown that the labelling intensity of a phosphatidylserine/phosphatidylcholine coating depends largely on the conditions of fixation. In fact, the usual aldehydic fixatives washed out most of the phostphatidylserine, thus preventing the binding of anti-phosphatidylserine antibodies. This was confirmed on biological samples such as rat liver and brain by measuring the loss of radiolabelled lipids during the fixation procedure. Furthermore, the complete procedure of tissue preparation for electron microscopical observation was investigated. The loss of (radiolabelled) lipids was studied in tissue samples during fixation and resin embedding. The results showed that the classical procedure (glutaraldehyde fixation followed by epoxy resin embedding) results in the loss of 73-91% of the tissue lipids whereas in unfixed, freeze-substituted samples, more than 76% of the tissue lipids are preserved.

CD130 rather than CD126 expression is associated with disease activity in multiple myeloma

We analysed the expression of both components of IL-6R, CD126 the ligand binding protein and CD130 the signal transducing protein, on plasma cells from MGUS and multiple myeloma (MM) cases using flow cytometry. CD126 was detectable in 50% of either MGUS or MM patients without any change of expression during disease progression. In contrast, CD130 expression was up-regulated during tumoural expansion (43% of MM patients at diagnosis versus 88% at relapse). Finally, combining CD126 and CD130 expression we found a significant increase of the percentage of CD126+ CD130+ patients at relapse, underlying the crucial role of IL-6 response in the late stage of MM.

HLA-G expression in human melanoma cells: protection from NK cytolysis

Expression of the non-classical HLA-G class I antigen is physiologically restricted to a limited number of tissues including trophoblasts, and is thought to play a role in establishing tolerance of the fetus by the maternal immune system. We investigated whether ectopic expression of HLA-G could also be detected in tumor cells and confer them the ability to escape immune cytotoxic responses. High levels of all alternatively spliced HLA-G transcripts could be detected in melanoma cells by RT-PCR. Analysis of biopsies from a melanoma patient revealed a higher HLA-G transcription level in skin metastasis as compared to healthy skin, while specific amplification of the HLA-G5 transcript was only observable in the tumor. HLA-G protein expression could also be detected in two melanoma cell lines. HLA-G-positive tumors inhibit cytotoxic lysis by the NK cell line YT2C2-PR. This inhibition is not observed with B-EBV cell lines bearing matched class I specificities, and is thought to occur through interaction of HLA-G with inhibitory receptors that are distinct from known KIRs interacting with HLA-E or classical class I molecules. Together, these results confirm that HLA-G expression at the surface of tumor cells can participate in the evasion of antitumoral immune responses and favor tumor progression.