Retinoid-mediated inhibition of interleukin-12 production in mouse macrophages suppresses Th1 cytokine profile in CD4(+) T cells

Interleukin-12 (IL-12) plays a central role in the immune system by driving the immune response towards T helper 1 (Th1) type responses characterized by high IFN-gamma and low IL-4 production. In this study we investigated whether retinoid-mediated inhibition of interleukin-12 production in mouse macrophages could regulate cytokine profile of antigen (Ag)-primed CD4(+) Th cells. Pretreatment with retinoids (9-cis-RA, all-trans-RA, TTNPB) significantly inhibited IL-12 production by mouse macrophages stimulated with lipopolysaccharide (LPS) or heated-killed Listeria monocytogenes (HKL). Retinoid-pretreated macrophages reduced their ability to induce IFN-gamma and increased the ability to induce IL-4 in Ag-primed CD4(+) T cells. Addition of recombinant IL-12 to cultures of retinoid-pretreated macrophages and CD4(+) T cells restored IFN-gamma production in CD4(+) T cells. The in vivo administration of 9-cis-RA resulted in the inhibition of IL-12 production by macrophages stimulated in vitro with either LPS or HKL, leading to the inhibition of Th1 cytokine profile (decreased IFN-gamma and increased IL-4 production) in CD4(+) T cells. These findings may explain some known effects of retinoids including the inhibition of encephalitogenicity, and point to a possible therapeutic use of retinoids in the Th1-mediated immune diseases such as autoimmune diseases.

Mesohepatectomy

BACKGROUND

Formal anatomic (lobar) or extended hepatectomies are recommended for liver malignancies located centrally within the liver (Couinaud's segments IVA, IVB, V, and VIII). Mesohepatectomy, resection of central hepatic segments and leaving the right and left segments in situ, removes large central tumors preserving more functioning liver tissue than either extended left or right hepatectomy. Mesohepatectomy is a seldom used, technically demanding procedure, and its application is yet to be defined.

METHODS

Medical charts of 244 consecutive liver resection patients were reviewed retrospectively. Eighteen patients were treated with mesohepatectomy. Six patients had metastatic liver tumor (MLT), 11 had hepatocellular carcinoma (HCC), and 1 had gallbladder adenocarcinoma. The operative results were compared with groups of patients treated by lobar hepatectomy (n = 71) and extended left or right hepatectomy (n = 43).

RESULTS

The mean mesohepatectomy operative time was 238 versus 304 minutes in the extended group. Inflow occlusion mean time was longer in the mesohepatectomy group than in extended procedures, 45 versus 39 minutes (P = not significant). Comparing the extended hepatectomy group, the mesohepatectomy group had a mean operative estimated blood loss 914 cc versus 1628 cc (P <0.01), postoperative hospital stay 9 versus 16 days (P = 0.054) and volume of resected liver 560cc versus 1500cc (P <0.01) respectively. The late complication rate was lower in the mesohepatectomy group than in the extended group and was comparable to the lobar hepatectomy group (P = 0.05).

CONCLUSIONS

Despite its technical demands, mesohepatectomy should be considered as an alternative to extended hepatectomy for selected patients with primary and secondary hepatic tumors localized in middle liver segments, as its complication rate, postoperative recovery, and preserved liver tissue compare favorably with extended hepatic resection.

Correlation between physiological assessment and outcome after liver transplantation

BACKGROUND

Critical shortages of organ donors for transplantation require appropriate utilization of this scarce resource. The purpose of this study was to assess whether use of physiological parameters of preliver transplant recipients is helpful in determining eventual outcome.

METHODS

Between October 1989 and June 1999, 215 liver transplants were performed on 199 patients at the Vancouver Hospital nad Health Sciences Centre. Thirty-one patients undergoing transplantation between May 1993 and June 1994 were retrospectively evaluated to obtain a minimum 5-year follow-up. Variables examined included pretransplant activation status (status 1, at home; status 2, hospitalized; status 3, admitted to intensive care; status 4, mechanical ventilation), simplified acute physiological score (SAPS), Acute Physiology, Age, and Chronic Health Evaluation (APACHE) II, and APACHE III scores at the time of transplantation. The scores were correlated to posttransplant mortality and functional outcome.

RESULTS

The 5-year mortality for status 1 patients was 14.3% versus 30% for patients listed as status 2 or greater (P = not significant). There were no significant differences in any of the physiological scoring assessments with regard to posttransplant mortality or functional assessment. Of the surviving patients, 18 of 22 who were employed, in school, or active at home pretransplant returned to their pretransplant activity.

CONCLUSIONS

Detailed physiological scoring systems are no more accurate in predicting outcome after liver transplant than current listing status parameters.

Dominant negative down-regulation of endotoxin-induced tumor necrosis factor alpha production by Lps(d)/Ran

We recently showed that adenoviral transfer and expression of the Lps(d)/Ran gene isolated from endotoxin-resistant C3H/HeJ mice could protect endotoxin-sensitive mice from endotoxic shock. Elevation of proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-alpha), is thought to be essential for the development of septic shock. To investigate the extent to which Lps(d)/Ran affects TNF-alpha production, we transduced primary macrophages from endotoxin-sensitive and -resistant mice with adenoviral vectors expressing the wild-type and the mutant Lps/Ran cDNAs and other control genes, and compared the amount of TNF-alpha produced by these various transduced macrophages. Successful transfer and expression of Lps(d)/Ran cDNA in endotoxin-sensitive C3H/HeOuJ macrophages reduced TNF-alpha production upon lipopolysaccharide (LPS) stimulation, as compared with macrophages transduced with vectors expressing the wild-type Lps(n)/Ran cDNA, the green fluorescent protein gene, or the lacZ gene. On the other hand, successful transfer and expression of the wild-type Lps(n)/Ran cDNA in primary macrophages from endotoxin-resistant C3H/HeJ mice failed to induce TNF-alpha production to any significant extent unless a very high LPS concentration was used. Given our previous demonstration that Lps(n)/Ran functions effectively in restoring LPS responsiveness in B cells from C3H/HeJ mice, we conclude that Lps/Ran is involved in a CD14-independent signal transduction pathway. This dominant negative down-regulation by Lps(d)/Ran on TNF-alpha production by macrophages and probably other innate immune responses may be key to the development of an effective gene therapy for endotoxic or septic shock.

Induction of in vivo persistent anti-mycobacterial activity by interferon-gamma-secreting fibroblasts

To determine whether the paracrine secretion of interferon-gamma (IFN-gamma) can efficiently stimulate the resistance to Mycobacterium avium complex (MAC) infection, 3T3 fibroblasts were stably transduced to secrete IFN-gamma (500 units/10(6) cells/48 h) and their effects on MAC infection were investigated in genetically susceptible BALB/c mice, compared with that of free recombinant IFN-gamma (rIFN-gamma). Immunization with IFN-gamma-secreting fibroblasts (3T3-IFN-gamma) during intranasal infection with MAC resulted in a significant decrease in bacterial load of lung during the entire 8-week observation period, while rIFN-gamma reduced the bacterial load at initial 1 week but not by 8 weeks postinfection. Furthermore, immunization with the 3T3-IFN-gamma cells induced and maintained significantly higher levels of cytotoxic activity and nitric oxide production by lung cells than those of rIFN-gamma immunization. This work suggest that IFN-gamma-secreting fibroblasts may serve as a vehicle for paracrine secretion of IFN-gamma in immunotherapy of MAC infection.

Ruptured giant intrathoracic lipoblastoma in a 4-month-old infant: CT and MR findings

BACKGROUND

We describe a 4-month-old infant with a ruptured intrathoracic lipoblastoma arising from the parietal pleura and associated with a pleural effusion.

OBJECTIVE

The clinical presentation was rapidly evolving respiratory distress. The chest radiograph showed a large mass and a pleural effusion in the right thoracic cavity. CT demonstrated an inhomogeneous low-attenuation mass which was 7 cm in diameter and which showed areas of enhancement after intravenous contrast medium. MRI showed a fatty intrathoracic mass with intratumoral streaks and whorls, which were attributed to loose fibrovascular connective tissue on pathological examination.

RESULTS

Thoracotomy and pathological examination revealed a ruptured intrathoracic lipoblastoma arising from the parietal pleura.

CONCLUSION

The pleural effusion might have suggested rupture of the tumour.

Post-surgical shunt hepatopulmonary syndrome in a case of non-cirrhotic portal hypertension: lack of efficacy of shunt reversal

Hepatopulmonary syndrome, a consequence of significant liver disease and portal hypertension, is thought to be secondary to the effects of vasoactive substances, normally inactivated in the liver, on the pulmonary vasculature. We report a patient with preserved hepatic function who underwent a decompressive surgical porto-systemic shunt for non-cirrhotic portal hypertension. This patient developed hepatopulmonary syndrome with dyspnoea and oxygen desaturation 2 years post-surgical shunt. Over the next 7 years, the patient's respiratory function became increasingly impaired although hepatic function remained preserved. Because of the hypothesized role of porto-systemic shunting in the aetiology of this syndrome, the surgical shunt was successfully reversed angiographically. No improvement in dyspnoea or oxygen saturation occurred and liver transplantation was undertaken. Six months post-transplant, the patient has decreased his oxygen requirements and is free of dyspnoea. Our experience supports the causal role of porto-systemic shunting in the pathogenesis of hepatopulmonary syndrome but suggests that merely decreasing the extent of porto-systemic shunting is not beneficial. Liver transplantation remains the only reliable therapeutic modality available to these patients.

Inhibition of interleukin-12 production in lipopolysaccharide-activated macrophages by curcumin

Pharmacological control of interleukin-12 production may be a key therapeutic strategy for modulating immunological diseases dominated by type-1 cytokine responses. In this study we investigated the effects of curcumin (1,7-bis[4-hydroxy-3-methoxyphenyl]-1, 6-heptadiene-3,5-dione) on the production of interleukin-12 from mouse macrophages stimulated with lipopolysaccharide. Curcumin potently inhibited the production of interleukin-12 in a dose-dependent manner. The effect of curcumin on interleukin-12 p40 promoter activation was analyzed by transfecting RAW264.7 monocytic cells with p40 promoter/reporter constructs. The repressive effect mapped to a region in the p40 promoter containing a binding site for nuclear factor kappaB (p40-kappaB). Furthermore, activation of macrophages by lipopolysaccharide resulted in markedly enhanced binding activity to the kappaB site, which significantly decreased upon addition of curcumin. These results suggest that curcumin-induced inhibition of interleukin-12 production in macrophages may explain some of the biological effects of curcumin including its anti-inflammatory activity.

Liver transplantation for chronic hepatitis B infection with the use of combination lamivudine and low-dose hepatitis B immune globulin

Current protocols for prophylaxis against allograft reinfection after liver transplantation for chronic hepatitis B virus (HBV) infection include the administration of large doses of hepatitis B immune globulin (HBIG), with considerable associated economic costs. Monotherapeutic prophylaxis with lamivudine has been complicated by the development of resistant strains of HBV. We studied the effectiveness of a posttransplantation prophylaxis protocol using combination lamivudine and low-dose HBIG in 7 consecutive patients with chronic HBV infection, 4 of whom were serum HBV DNA positive before pretransplantation lamivudine therapy. All patients were serum HBV DNA negative at transplantation and received lamivudine, 100 mg/d, posttransplantation. HBIG, 2170 IU, was administered intramuscularly intraoperatively and daily for 14 days. Maintenance HBIG therapy consisted of 2170 IU intramuscularly twice weekly, tapered to every 2 to 4 weeks by 12 months posttransplantation. Target serum HBIG (HBV surface antibody) titers were less than 500 IU/L for 6 months, then greater than 300 IU/L until 12 months posttransplantation. Induction serum HBIG titers were determined daily in 5 patients, and both serum HBIG and hepatitis B surface antigen were determined every 4 weeks in all patients. One patient died 61 days posttransplantation; the surviving patients (n = 6) were followed up for a mean of 532 days (range, 395 to 648 days). No patient has developed allograft reinfection. In the induction period, a target HBIG titer of greater than 500 IU/L was not achieved until a mean of 6.8 days (range, 5 to 10 days). In the maintenance period, all patients achieved the target HBIG titer. This suggests combination lamivudine and low-dose HBIG is effective in preventing allograft reinfection by HBV.

Chloromethyl ketones inhibit interleukin-12 production in mouse macrophages stimulated with lipopolysaccharide

Interleukin-12 (IL-12) plays a pivotal role in the development of T-helper type 1 (Th1) immune response, which may be involved in the pathogenesis of chronic inflammatory autoimmune disorders. In this study, we investigated the effects of N-alpha-tosyl-L-phenylalanine chloromethyl ketone (TPCK) and N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK), serine protease inhibitors, on the production of IL-12 from macrophages stimulated with lipopolysaccharide (LPS). TPCK and TLCK potently inhibited this LPS-induced IL-12 production in a dose-dependent manner. The effect of TPCK and TLCK on the IL-12 p40 promoter activation was analyzed by transfecting monocytic RAW264.7 cells with p40 promoter-reporter constructs. The repressive effect maps to a region in the p40 promoter containing a binding site for NFkappaB (p40-kappaB). A linker scan mutant of the p40-kappaB site abrogates the inhibitory effect on the p40 promoter, confirming the functional relevance of the NFkappaB site. Our results show that TPCK and TLCK inhibit NFkappaB-mediated IL-12 production in macrophages. reserved.

Lps(d)/Ran of endotoxin-resistant C3H/HeJ mice is defective in mediating lipopolysaccharide endotoxin responses

C3H/HeJ inbred mice are defective in that they are highly resistant to endotoxic shock as compared with normal responder mice. Their B cells and macrophages do not respond significantly when exposed to lipopolysaccharide (LPS), whereas cells from the responder mice do. Using a functional assay, we previously isolated a cDNA, which encodes for Ran/TC4 GTPase. We now show that this gene is mutated in C3H/HeJ mice, which accounts for their resistance to endotoxin stimulation. Sequence analysis of independent mutant Lps(d)/Ran cDNAs isolated from splenic B cells of C3H/HeJ mice reveals a consistent single base substitution at position 870, where a thymidine is replaced with a cytidine. In situ hybridization maps the Lps(d)/Ran cDNA to mouse chromosome 4. By retroviral gene transfer, the wild-type Lps(n)/Ran cDNA but not the mutant Lps(d)/Ran cDNA can restore LPS responsiveness of C3H/HeJ cells. Adenoviral gene transfer in vivo with the mutant Lps(d)/Ran cDNA but not the wild-type Lps(n)/Ran cDNA rescues endotoxin-sensitive mice from septic shock. Thus Lps/Ran is an important target for LPS-mediated signal transduction, and the Lps(d)/Ran gene may be useful as a therapeutic sequence in gene therapy for endotoxemia and septic shock.

Sulfasalazine prevents T-helper 1 immune response by suppressing interleukin-12 production in macrophages

Interleukin-12 (IL-12) plays a pivotal role in the development of T-helper 1 (Th1) immune response, which may be involved in the pathogenesis of chronic inflammatory autoimmune disorders. In this study we investigated the effects of sulfasalazine, a drug for treating inflammatory bowel disease and rheumatoid arthritis, on the production of IL-12 from mouse macrophages stimulated with lipopolysaccharide (LPS). Sulfasalazine potently inhibited the production of IL-12 in a dose-dependent manner, in part through the down-regulation of nuclear factor kappaB (NFkappaB) activation in IL-12 p40 gene. Activation of macrophages by LPS resulted in markedly enhanced binding activities to the kappaB site, which significantly decreased upon addition of sulfasalazine as demonstrated by an electrophoretic gel shift assay. Importantly, macrophages pretreated with sulfasalazine either in vitro or in vivo reduced their ability to induce interferon-gamma (IFN-gamma) and increased the ability to induce IL-4 in antigen-primed CD4+ T cells. From these results, sulfasalazine may induce the Th2 cytokine profile in CD4+ T cells by suppressing IL-12 production in macrophages, and sulfasalazine-induced inhibition of IL-12 production in macrophages may explain some of the known biological effects of sulfasalazine.

Antigen-specific cytotoxicity and cell number of adoptively transferred T cells are efficiently maintained in vivo by re-stimulation with an antigen/interleukin-2 fusion protein

In order to maintain in vivo anti-tumor efficacy of antigen (Ag)-specific T cells in adoptive immunotherapy for a prolonged period, we constructed a fusion protein (OVA/IL-2) containing ovalbumin (OVA) as a model tumor Ag, co-valently linked to murine interleukin-2 (IL-2). The OVA/IL-2 protein produced in a baculovirus expression system displayed potent IL-2 bio-activity. Immunization with the OVA/IL-2 protein after adoptive transfer of OVA-specific T cells maintained the OVA-specific cytotoxicity and cell number of adoptively transferred T cells long term in vivo, while a simple mixture of recombinant OVA (rOVA) and rIL-2 did not. The response was dependent on the injection doses and times of the OVA/IL-2 protein. Furthermore, weekly re-stimulation of adoptively transferred OVA-specific T cells with the OVA/IL-2 protein cured 70% of tumor-bearing mice. In contrast, re-stimulation with a mixture of rOVA and rIL-2 could not significantly prolong the survival period of tumor-bearing mice. These studies suggest that the co-valent linkage between IL-2 and antigen confines the effect of IL-2 to antigen-specific T cells, leading to efficient maintenance of the anti-tumor activity of adoptively transferred T cells.

Assessment of immunologic status of liver transplant recipients by peripheral blood mononuclear cells in response to stimulation by donor alloantigen

OBJECTIVE

To determine whether there is a role for assessing peripheral blood mononuclear cell (PBMC) cytokine patterns as a means of measuring the immunologic and clinical status of liver transplant recipients.

SUMMARY BACKGROUND DATA

The role of assessing cytokine patterns in the prediction of clinical graft rejection or acceptance remains unclear. The purpose of this study was to examine the cytokine profiles of PBMC stimulated in vitro with donor alloantigen and to correlate prospectively the data with clinical assessment of graft status in orthotopic liver transplant (OLT) recipients.

METHODS

PBMCs from OLT recipients were examined for proliferation and cytokine mRNA expression after stimulation by donor alloantigen, third-party alloantigen, or phytohemagglutinin (PHA). mRNA extracted from PBMC was amplified by reverse transcriptase-polymerase chain reaction with oligospecific primer pairs for interleukin (IL)-2, IL-4, IL-6, IL-10, interferon (IFN) gamma, tumor necrosis factor (TNF) alpha and transforming growth factor (TGF) beta. Results were prospectively correlated with each patient's allograft status.

RESULTS

Increased IL-4 and TGF-beta and decreased IL-2, IFNgamma, and TNF-alpha mRNA expression by PBMCs in response to donor alloantigen stimulation predicted immunologic graft stability over a minimum 60-day interval compared with mRNA expression of PBMCs from patients with established rejection or those who experienced a rejection episode within a 30-day period (p < 0.05). Stimulation of recipient PBMCs with third-party alloantigens or PHA yielded similar but less specific results. PBMC proliferation to varying antigenic stimulation did not correlate with clinical graft status, nor did cytokine production by unstimulated PBMC.

CONCLUSIONS

Prospective assessment of cytokine expression by PBMC from OLT recipients in response to stimulation by donor alloantigen is helpful for predicting the clinical status of the allograft and may be useful in the development of more precise immunologic monitoring protocols.

A rapid restriction fragment length polymorphism polymerase chain reaction-based diagnostic method for identification of T-cell lymphoproliferative disorders

BACKGROUND

Identification of a clonal proliferation of lymphocytes is central to the diagnosis of lymphoma compared with a reactive lymphoproliferation. We propose a novel diagnostic technique based on restriction fragment length polymorphism (RFLP) of amplified polymerase chain reaction (PCR) products of the T-cell receptor -gamma (TCR-gamma) gene rearrangement to rapidly identify monoclonality in T-cell lymphomas and improve diagnosis of malignancy.

MATERIALS AND METHODS

DNA from peripheral blood mononuclear cells (PBMCs) of 10 healthy volunteers and 7 T-cell lymphoma patients were isolated and the TCR-gamma was amplified with consensus primers for the different variable (V) and joining (J) segments. Restriction digests were done using BstN1 and the fragments separated via gel electrophoresis. Verification was by Southern analysis.

RESULTS

Restriction digests of the 10 healthy controls show a characteristic nine-band digest pattern whereas the restriction digests of the 7 T-cell lymphomas each show altered banding patterns completely distinct from the normal nine-band pattern (Fisher exact test = 0.00005). Sensitivity assays demonstrate the test can detect clonal populations representing 2% of total. This method also enables identification of particular clonal populations. The entire procedure can be performed in one day, does not require radioactivity, and requires only small quantities of specimens.

CONCLUSIONS

This RFLP-PCR-based diagnostic method for T-cell lymphomas is specific, sensitive, efficient, and reproducible, and enables the identification of clonally expanded populations of T lymphocytes. It offers the ability to identify particular clonal populations, as with Southern analysis, combined with the benefits of a PCR method.

Interleukin-12-secreting fibroblasts are more efficient than free recombinant interleukin-12 in inducing the persistent resistance to Mycobacterium avium complex infection

To determine whether the paracrine secretion of interleukin-12 (IL-12) can efficiently stimulate the resistance to Mycobacterium avium complex (MAC) infection, 3T3 fibroblasts were stably transfected to secrete IL-12 (480 U/106 cells/48 hr) and their effect on MAC infection was investigated in genetically susceptible BALB/c mice, compared with that of free recombinant IL-12 (rIL-12). Injection with IL-12-secreting fibroblasts (3T3-IL-12) during intranasal infection with MAC resulted in a significant decrease in the bacterial load of the lung during the entire 10-week observation period, while rIL-12 reduced the bacterial load initially, at 2 weeks, but not by 10 weeks postinfection. Lung CD4+ T cells in mice injected with the 3T3-IL-12 cells showed a persistent T helper type 1 (Th1) response throughout the 10-week period. Furthermore, immunization with the 3T3-IL-12 cells induced and maintained significantly higher levels of cytotoxic activity and nitric oxide production by lung cells than did rIL-12 immunization. This work suggests that IL-12-secreting fibroblasts may serve as a vehicle for paracrine secretion of IL-12 for immunotherapy of MAC infection.

Spontaneous patterning of quantum dots at the air-water interface

Nanoparticles deposited at the air-water interface are observed to form circular domains at low density and stripes at higher density. We interpret these patterns as equilibrium phenomena produced by a competition between an attraction and a longer-ranged repulsion. Computer simulations of a generic pair potential with attractive and repulsive parts of this kind, reproduce both the circular and stripe patterns. Such patterns have a potential use in nanoelectronic applications.

Racial differences between solid organ transplant donors and recipients in British Columbia: a five-year retrospective analysis

BACKGROUND

We attempted to determine whether significant racial differences exist between organ donors and transplant recipients in British Columbia, and whether differences exist between individual organ transplant programs (lung, heart, kidney, liver, and pancreas). The design of the study was a retrospective review.

METHODS

We used the database of the British Columbia Transplant Society, a provincial agency, for the years 1992 to 1997 inclusive. The outcome measures were a comparison of racial characteristics of organ donors and transplant recipients collectively and by individual organ transplant program.

RESULTS

There were 236 organ donors and 766 transplant recipients. Comparing racial groups between donors and recipients, Caucasians contributed the most donors (93.2%) but received proportionately fewer organs (73.4%, P<0.000001). Orientals donated 3.4% of all organs but constituted 14.4% of all recipients (P<0.00001). Non-Oriental, non-Caucasians (predominantly Asian Indians and Native Aboriginals) constituted 3.4% of all donors and 12.2% of all recipients (P=0.0001). Among the individual organ transplant programs, lung, heart, and pancreas recipients were predominantly Caucasian (148 of 156 recipients). Oriental recipients were more likely to be kidney recipients (19.8% of all kidney recipients) compared with all Oriental recipients (P<0.000001). Likewise, Asian Indians were more likely to be kidney recipients (7.2% of all kidney recipients) compared with all Asian Indian recipients (P<0.0001). Native Aboriginals, however, were more likely to be liver allograft recipients (8.3% of all liver transplants) than nonliver allograft recipients (P=0.017).

CONCLUSIONS

In British Columbia, disparity exists between Oriental and non-Oriental, non-Caucasian donors and recipients. Orientals and Asian Indians were more likely to be kidney graft recipients than nonkidney graft recipients, whereas Native Aboriginal recipients seemed more likely to have undergone liver transplantation.

Chemo-embolization of hepatic tumours

Over the past decade, increasing use of chemo-embolization with chemotherapeutic agents emulsified in oil has been made in the treatment of both primary and metastatic liver tumours. These lesions are often not amenable to surgical resection and are not responsive to systemic chemotherapy. Chemo-embolization provides an additional therapeutic option which, in some instances, can provide significant benefit. This pictorial review discusses the technique of chemo-embolization, as well as aspects of patient selection, complications, and tumour response.

Radiofrequency ablation followed by resection of malignant liver tumors

BACKGROUND

Radiofrequency ablation (RFA) has recently been used to treat liver tumors, but few clinical reports have described the pathological characteristics of radiofrequency ablation in human specimens. This study delineates the gross pathologic and histochemical changes induced by RFA in benign and malignant human liver tissue and confirms the tumor necrosis described in early clinical reports.

METHODS

Ten patients with metastatic tumors of the liver received a single treatment of ultrasound-guided percutaneous RFA to 12 tumors. Hepatic resection was carried out within 6 weeks of RFA. Specimens were stained with standard hematoxylin and eosin stain followed by oxidative stain to determine if there was evidence of viable tumor within the zone of ablation.

RESULTS

Nine of the 12 ablations were resected. Microscopic examination within the zone of ablation showed successful ablation in 8 of the 9 resected ablations.

CONCLUSIONS

Percutaneous RFA creates well-circumscribed areas of tumor necrosis with apparent cell death using an oxidative stain. Further investigation is encouraged to determine the clinical effectiveness of radiofrequency ablation in the complete destruction of liver tumors for palliative or curative intent.

Retinoids inhibit interleukin-12 production in macrophages through physical associations of retinoid X receptor and NFkappaB

Lipopolysaccharide (LPS) increases the production of interleukin-12 (IL-12) from mouse macrophages via a kappaB site within the IL-12 p40 promoter. In this study, we found that retinoids inhibit this LPS-stimulated production of IL-12 in a dose-dependent manner. The NFkappaB components p50 and p65 bound retinoid X receptor (RXR) in a ligand-independent manner in vitro, and the interaction interfaces involved the p50 residues 1-245, the p65 residues 194-441, and the N-terminal A/B/C domains of RXR. Activation of macrophages by LPS resulted in markedly enhanced binding activities to the kappaB site, which significantly decreased upon addition of retinoids, as demonstrated by the electrophoretic mobility shift assays. In cotransfections of CV-1 and HeLa cells, RXR also inhibited the NFkappaB transactivation in a ligand-dependent manner, whereas a mutant RXR lacking the AF2 transactivation domain, which serves as ligand-dependent binding sites for transcription integrators SRC-1 and p300, was without any effect. In addition, coexpression of increasing amounts of SRC-1 or p300 relieved the retinoid-mediated inhibition of the NFkappaB transactivation. From these results, we propose that retinoid-mediated suppression of the IL-12 production from LPS-activated macrophages may involve both inhibition of the NFkappaB-DNA interactions and competitive recruitment of transcription integrators between NFkappaB and RXR.

TCR diversity in gammadeltaTCR+ hybridomas derived from mice given portal vein donor-specific pre-immunization and skin allografts

Portal venous (p.v.) immunization with multiple minor histoincompatible cells leads to antigen-specific increased skin allograft survival. GammadeltaTCR+ hybridoma cells, prepared from mesenteric lymphocytes of p.v. immunized animals, can adoptively transfer this increased graft survival to naive animals. We have analyzed VgammaVdelta gene usage, and TCR gamma-chain junctional diversity in gammadeltaTCR+ hybridomas from mice immunized with different antigen combinations by p.v. or conventional lateral tail vein (i.v.) immunization. Following p.v. immunization two independent sets of hybridoma cells were derived, one expressing a common gamma-chain junctional sequence which was also found in > 85% of the hybridomas derived following i.v. immunization, while the other set showed remarkable gamma-chain junctional sequence diversity. The diversity seen in these latter hybridomas was associated with the antigen specificity of the hybridoma cells. Cells expressing these 'unique' TCR junctional sequences were stimulated to produce cytokines both by hsp and by minor-histocompatibility-specific irradiated peritoneal cells. Cells expressing TCR with a common gamma-chain junctional sequence were stimulated to cytokine production by MHC-matched but minor-histocompatibility mismatched (as well as matched) peritoneal cells, but not by hsp. We suggest that p.v. immunization results in stimulation of both antigen-specific and non-specific regulatory gammadeltaTCR+ cells, which can be distinguished by gamma-chain TCR sequence diversity.

Donor-specific stimulation of peripheral blood mononuclear cells from recipients of orthotopic liver transplants is associated, in the absence of rejection, with type-2 cytokine production

In this study, we examined the cytokine production by human peripheral blood mononuclear cells (PBM) from recipients of orthotopic liver transplants which had been stimulated by donor-specific alloantigen. Levels of interleukin (IL)-2, IL-4, interferon (IFN)-gamma, IL-10 and transforming growth factor (TGF)-beta produced in vitro from PBM of 15 transplant recipients at 5-7 months post transplantation were analysed after donor-specific, third-party, or non-specific stimulation. Mononuclear cell proliferation in response to stimulation and cytokine mRNA from the cell cultures were assayed. Donor-specific antigen was obtained from donor spleen cells which had been obtained and frozen in liquid nitrogen at the time of organ retrieval. Third-party restimulation used equivalent numbers of spleen cells pooled from the other 14 organ donors. Cytokine production was correlated with the clinical condition of the patient, including biopsy results when available, and biochemical data. The data show a highly significant correlation between the donor-specific- and third-party- stimulated IL-4 and IL-10 production from recipient PBM with stable liver graft function as assessed by histopathology and/or biochemistry. This correlation was independent of level of immunosuppression. These data strongly support a role for IL-4 and/or IL-10 in the induction and/or maintenance of tolerance to human liver allografts. Measurement of the levels of these cytokines from recipient PBM after donor-specific antigen stimulation in vitro may be a useful test for monitoring for acute allograft rejection.