PubMed Health⌕ Search

Biomedical subjects

M C Falk

Publications and source records attributed to M C Falk.

At least 19 recordsLinked to original sources
PubMed2000

Novel surveillance and cure of a donor-transmitted lymphoma in a renal allograft recipient.

BACKGROUND: In this report we describe a malignant lymphoma of donor origin inadvertently transplanted into two renal allograft recipients, despite standard comprehensive donor screening. The successful clearance of the tumor from both patients and a novel method of surveillance are detailed. METHODS: Initial management consisted of withdrawal of immunosuppression to promote rejection of the allograft and the transplanted tumor in both patients, followed by graft removal. Peripheral blood microchimerism was assessed in both recipients using nested polymerase chain reaction to detect the DYZ3 gene on the Y chromosome (donor male, recipients female). RESULTS: Although microchimerism was detected on day 6 after transplantation and day 1 after explantation, repeat peripheral blood examination at 1, 3, and 6 months after explantation demonstrated no microchimerism. Both patients remain well at 12 months and have been relisted for transplantation. CONCLUSION: Despite inadvertent transplantation of a previously undiagnosed malignancy of donor origin, the recipients' immune response was able to eliminate donor tumor cells after the withdrawal of immunosuppression. Repeated surveillance of peripheral blood from both recipients, using a novel application of the technique of nested polymerase chain reaction to amplify donor DNA, demonstrated no persistence of donor cells, supporting effective eradication of the donor malignancy.

Aged↗
PubMed1999

Activation and adoptive transfer of Epstein-Barr virus-specific cytotoxic T cells in solid organ transplant patients with posttransplant lymphoproliferative disease.

The treatment of Epstein-Barr virus (EBV)-associated lymphoproliferative disease (PTLD) in EBV seronegative solid organ transplant recipients who acquire their EBV infection after engraftment poses a considerable challenge because of underlying immunosuppression that inhibits the virus-specific cytotoxic T cell (CTL) response in vivo. We have developed a protocol for activating autologous EBV-specific CTL lines from these patients and show their potential use for immunotherapy against PTLD in solid organ transplant patients. Peripheral blood mononuclear cells from a panel of solid organ transplant recipients with and without active PTLD were used to assess EBV-specific memory CTL responses. The activation protocol involved cocultivation of peripheral blood mononuclear cells with an autologous lymphoblastoid cell line under conditions that favored expansion of virus-specific CTL and hindered the proliferation of allospecific T cells. These CTL consistently showed (i) strong EBV-specificity, including reactivity through defined epitopes in spite of concurrent immunosuppressive therapy, and (ii) no alloreactivity toward donor alloantigens. More importantly, adoptive transfer of these autologous CTLs into a single patient with active PTLD was coincident with a very significant regression of the PTLD. These results demonstrate that a potent EBV-specific memory response can be expanded from solid organ recipients who have acquired their primary EBV infection under high levels of immunosuppressive therapy and that these T cells may have therapeutic potential against PTLD.

Adoptive Transfer↗
PubMed1999

The kinetics of mycophenolic acid and its glucuronide metabolite in adult kidney transplant recipients.

BACKGROUND: Mycophenolic acid kinetics have been reported to vary after renal transplantation, and mycophenolic acid area under the concentration-time curve (AUC) is the best predictor of suppression of graft rejection. METHODS: To determine whether mycophenolic acid kinetics vary after renal transplantation and to examine the potential role of enterohepatic recirculation, we investigated the kinetics of mycophenolic acid and mycophenolic acid glucuronide on days 2, 5, and 28 after transplantation in 10 kidney transplant recipients (male/female ratio, 1.5; mean age, 41.7 +/- 5.0 years) given 1 g mycophenolate mofetil twice a day. To facilitate therapeutic drug monitoring, we examined a limited sampling strategy for estimating 12-hour mycophenolic acid [AUC(0-12)]. RESULTS: The mean +/- SE AUC(0-12) for mycophenolic acid on day 28 was 38.5 +/- 1.6 mg x h/L, with a secondary peak 4 to 8 hours after dosing that was attributable to enterohepatic recirculation. Marked variability was shown in the kinetic profile of mycophenolic acid among patients across the three sampling days. Mycophenolic acid AUC(0-12) was positively predicted by both serum creatinine (P = .01) and serum albumin (P = .03) but not by time after transplantation, body weight, or trough concentration. Limited sampling (at 0, 1, 3, and 6 hours) accounted for 84.1% of the variability in the mycophenolic acid AUC(0-12) data and predicted the AUC(0-12) closely (r2 = 0.954) when evaluated in 10 different kidney transplant recipients. CONCLUSIONS: Mycophenolic acid AUC(0-12) is predicted by serum albumin and creatinine after kidney transplantation, and the AUC(0-12) may be determined during the early posttransplant period while the patient remains hospitalized with use of a limited sampling strategy to facilitate therapeutic drug monitoring.

Adult↗
PubMed1999

Apoptosis and expression of cytotoxic T lymphocyte effector molecules in renal allografts.

Cytotoxic T lymphocyte (CTL) mediated apoptosis is thought to play a major role in the rejection of renal allografts following transplantation, however, the CTL effector mechanism that is primarily responsible for immunological rejection is unknown. The two major effector pathways of CTL killing which lead to apoptosis involve the Fas/Fas ligand (Fas L) lytic pathway, and the perforin/granzyme degranulation pathway. The expression of CTL effector molecules which influence these pathways include Fas, Fas L and TiA-1 (cytotoxic granule protein). This study has investigated apoptosis by in situ terminal deoxytransferase-catalysed DNA nick end labelling (TUNEL), and the expression of CTL effector molecules by immunohistochemistry, in renal allograft biopsies obtained from patients following kidney transplantation. Renal biopsies were classified into three histological groups; acute cellular rejection, chronic rejection, or no rejection. The extent of T-cell infiltration of renal tissues was assessed by immunohistochemical staining with an anti-CD3 monoclonal antibody. Numerous TUNEL positive cells were detected in all transplant biopsies examined; these consisted mainly of renal tubular cells and infiltrating cells, with some TUNEL positive cells also detected in the glomeruli. In the case of normal kidney tissue, renal cells also stained positive for TUNEL but there was no lymphocytic infiltration. There was significantly more T-cell infiltration observed in acute rejection biopsies compared to the no rejection biopsies. In the case of Fas L expression, there was little expression in all three biopsy groups, apart from one case of chronic rejection. Conversely, although there were no significant differences in TiA-1 expression between the three biopsy groups, TiA-1 expression was more prominent in acute rejection biopsies. Furthermore, Fas expression was significantly decreased in acute rejection biopsies when compared to those of chronic and no rejection in which Fas was predominantly localized in the renal tubular cells. These results indicate that the mechanism of CTL killing leading to the rejection of renal allografts may be different in acute and chronic rejection. Moreover, our data indicate the potential for cytotoxic granule-based CTL killing in acute renal allograft rejection but not in chronic rejection.

Adult↗
PubMed1999

Expression of apoptotic regulatory molecules in renal cell carcinoma: elevated expression of Fas ligand.

Renal cell carcinoma (RCC) is the most common renal neoplasm. Despite being infiltrated by tumour infiltrating lymphocytes (TIL), these TIL are unable to control tumour growth in vivo, suggesting that the cytotoxic capacity of TIL against RCC is impaired, or that the tumour cells are resistant to killing and therefore escape detection by the immune system. It is postulated that the expression of apoptotic regulatory molecules in RCC favours tumour cell survival. The present study has therefore determined the expression of Fas (APO-1/CD95), Fas ligand (Fas L) and bcl-2 in these tumours. The expression of Fas, Fas L and bcl-2 mRNA transcripts was determined in RCC, normal kidney and peripheral blood by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), following RNA extraction and cDNA synthesis from tissues and cell samples. Transcript levels were measured by densitometry after Southern blot hybridization of PCR products with internal radio-labelled oligonucleotide probes; a densitometry score was assigned to each hybridizing DNA band and expressed as a ratio of the glyceraldehyde-3-phosphate dehydrogenase content. In peripheral blood, the expression of Fas L and bcl-2 transcripts was similar between patients and normal healthy individuals; however, Fas transcript expression was significantly down-regulated in the patients' versus normal peripheral blood (P = 0.026). Most interestingly, significantly up-regulated Fas L expression was observed in RCC compared to normal kidney (P = 0.041). In contrast, bcl-2 transcripts were well represented in normal kidney but markedly decreased in RCC (P = 0.021). The expression of Fas transcripts in normal kidney and RCC was variable. These data demonstrate elevated expression of Fas L transcripts in RCC, but the functional relevance of this remains to be investigated.

Adult↗
PubMed1998

Advanced donor-origin melanoma in a renal transplant recipient: immunotherapy, cure, and retransplantation.

BACKGROUND: A kidney transplant recipient inadvertently contracted donor-origin melanoma, which was found to be very advanced at presentation. Withdrawal of immunosuppression failed to induce rejection, and interferon-alpha was required. When florid allograft rejection was in progress, the allograft was removed, before it was recognized that the transplanted melanoma was not being simultaneously rejected. METHODS: Subsequent immunotherapy was required, which largely recapitulated treatment of recognized value in autologous melanoma and included interferon-alpha, use of cultured melanoma cells as tumor vaccine, pooled allogeneic cell vaccination, and adoptive immunotherapy using lymphokine-activated killer cells. RESULTS: Prolonged immunotherapy eradicated the widespread malignancy, and the patient went on to a successful second renal transplant, with follow-up of over 24 months. CONCLUSIONS: This unique case demonstrates the successful cure of advanced transplanted melanoma through the use of immunotherapy, which did not require sophisticated tumor vaccine technology, and successful retransplantation.

Adult↗
PubMed1998

Expression of cytokine mRNA transcripts in renal cell carcinoma.

Renal cell carcinoma (RCC) is a solid tumour of the kidney and is the most common renal neoplasm. Despite the presence of tumour infiltrating lymphocytes (TIL) in RCC, these tumours continue to progress in vivo suggesting a poor host immune response to the tumour, and the suppression of TIL effector function. Cytokines are key molecules that modulate the function of T cells. The possibility is investigated that the local production of cytokines in RCC contributes to immunosuppression of TIL. The expression of pro-inflammatory (IFN-gamma/IL-2) and immunosuppressive (IL-10/TGF-beta) cytokine mRNA transcripts was determined in RCC, normal kidney and peripheral blood of RCC patients using a semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) with cytokine-specific primers. Following Southern blot hybridization of the PCR products with internal radiolabelled oligonucleotide probes, cytokine transcript levels were measured by densitometry and expressed relative to the glyceraldehyde-3-phosphate dehydrogenase densitometry score. With the exception of IL-10, there were no differences in expression of cytokine mRNA transcripts between the peripheral blood of patients and normal healthy individuals. It was found that TGF-beta transcripts were well represented in normal kidney and RCC. In contrast, the expression of IFN-gamma transcripts, while low in the majority of samples, was significantly increased in RCC when compared to normal kidney (P=0.05). The IL-2 and IL-10 transcripts showed a more variable expression in normal kidney and RCC, with no significant differences in expression between the sample groups. The data demonstrating pro-inflammatory and immunosuppressive cytokine expression in RCC do not support a prominent immunosuppressive cytokine profile in these tumours.

Adult↗
PubMed1998

T cell engraftment in lymphoid tissues of human peripheral blood lymphocyte reconstituted SCID mice with or without prior activation of cells.

The reconstitution of severe combined immunodeficiency (SCID) mice with human PBL (Hu-PBL-SCID) was assessed using fresh unstimulated PBL and anti-CD3-stimulated PBL. Mice were reconstituted with PBL by intraperitoneal injection of 1-2.5 x 107 PBL in PBS; controls received PBS. Successful engraftment of human PBL in SCID mice was determined by measurement of human IgG in mouse sera, polymerase chain reaction (PCR) detection of human-specific HLA-DRbeta DNA in SCID periphery, and immunohistochemical staining of mouse tissues (spleen, lymph nodes, thymus, liver and lung) with antibodies specific for human CD45 and CD3. Human IgG was detected 1 week after reconstitution in sera of all animals that received at least 1 x 107 PBL and continued to increase for 8 weeks. Human-specific HLA-DRbeta DNA was detected in the majority of mice 3 weeks after reconstitution but not in controls. Moreover, immunohistochemical analysis of Hu-PBL-SCID mouse tissues revealed the presence of human CD45+ cells in all tissues examined. CD3+ T cell engraftment was observed in lymphoid tissues irrespective of whether PBL had been activated prior to transfer or not.

Animals↗
PubMed1998

Pulmonary and hepatic gene expression following cecal ligation and puncture: monophosphoryl lipid A prophylaxis attenuates sepsis-induced cytokine and chemokine expression and neutrophil infiltration.

Polymicrobial sepsis induced by cecal ligation and puncture (CLP) reproduces many of the pathophysiologic features of septic shock. In this study, we demonstrate that mRNA for a broad range of pro- and anti-inflammatory cytokine and chemokine genes are temporally regulated after CLP in the lung and liver. We also assessed whether prophylactic administration of monophosphoryl lipid A (MPL), a nontoxic derivative of lipopolysaccharide (LPS) that induces endotoxin tolerance and attenuates the sepsis syndrome in mice after CLP, would alter tissue-specific gene expression post-CLP. Levels of pulmonary interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), granulocyte colony-stimulating factor (G-CSF), IL-1 receptor antagonist (IL-1ra), and IL-10 mRNA, as well as hepatic IL-1beta, IL-6, gamma interferon (IFN-gamma), G-CSF, inducible nitric oxide synthase, and IL-10 mRNA, were reduced in MPL-pretreated mice after CLP compared to control mice. Chemokine mRNA expression was also profoundly mitigated in MPL-pretreated mice after CLP. Specifically, levels of pulmonary and hepatic macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, MIP-2, and monocyte chemoattractant protein-1 (MCP-1) mRNA, as well as hepatic IFN-gamma-inducible protein 10 and KC mRNA, were attenuated in MPL-pretreated mice after CLP. Attenuated levels of IL-6, TNF-alpha, MCP-1, MIP-1alpha, and MIP-2 in serum also were observed in MPL-pretreated mice after CLP. Diminished pulmonary chemokine mRNA production was associated with reduced neutrophil margination and pulmonary myeloperoxidase activity. These data suggest that prophylactic administration of MPL mitigates the sepsis syndrome by reducing chemokine production and the recruitment of inflammatory cells into tissues, thereby attenuating the production of proinflammatory cytokines.

Adjuvants, Immunologic↗
PubMed1997

Characterisation of gamma delta T cells in renal cell carcinoma patients by polymerase chain reaction analysis of T cell receptor transcripts.

Renal cell carcinomas (RCC) contain tumour infiltrating lymphocytes (TIL) but these are essentially immunosuppressed in that they do not generate effective antitumour immune responses in vivo. These TIL comprise predominantly alpha beta T cells, although gamma delta T cells are also present. The repertoire of gamma delta T cells in RCC, however, has not been fully investigated. To identify the gamma delta T cell populations infiltrating RCC, this study has characterised the gamma delta T cell receptor (TCR) repertoire expression in these tumours and compared this to autologous normal kidney and autologous peripheral blood. A semi-quantitative reverse transcriptase/polymerase chain reaction technique was used for amplification of rearranged TCR V-C mRNA transcripts. Primers specific for the four human TCR V gamma and six V delta subfamilies were used, each in conjunction with a primer specific for either the C gamma or C delta region. The specificity of the PCR products was confirmed by Southern blotting and hybridisation with an internal C region probe. A densitometry score was assigned to each DNA band and the level of V gene expression was determined as ratio of C delta gene expression. The gamma delta TCR expression in each sample was determined as a ratio of C delta: glyceraldehyde phosphate dehydrogenase densitometry score. This demonstrated that TCR C delta gene expression was significantly higher in RCC compared to normal kidney (P < 0.019), suggesting a selective infiltration of gamma delta T cells into the tumour. Furthermore, we observed differences in the TCR V gamma and V delta repertoires between RCC and peripheral blood. V gamma l expression was significantly decreased (P < 0.043) whereas there was an over-representation of V gamma 4 transcripts (P < 0.028) in RCC compared to blood. A significant reduction in expression of both V delta 1 (P < 0.028) and V delta 3 (P < 0.051) was also observed within kidney tumour compared to peripheral blood. These findings show that expression of the gamma delta TCR repertoire in RCC differs from that in peripheral blood and normal kidney.

Carcinoma, Renal Cell↗
PubMed1997

Expression of the mucosal gamma delta T cell receptor V region repertoire in patients with IgA nephropathy.

IgA nephropathy (IgAN) is characterized by the deposition of IgA in the glomerular mesangium and often leads to progressive renal dysfunction and kidney failure. We have previously shown that the mesangial IgA is likely to derive from the bone marrow plasma cells, and suggested that a primary abnormality within the mucosal immune system may underly the pathogenesis of IgAN. This study has analyzed the T cell receptor (TCR) variable (V) region expression by gamma delta T cells in the intestinal mucosa of patients with IgAN. The V gamma and V delta usage of TCR transcripts was determined using a semiquantitative reverse transcriptase-PCR protocol. Primers specific for the four human V gamma and six V delta subfamilies were used each with a constant (C) gamma or C delta specific primer, and the PCR-amplified TCR transcripts were detected by Southern blotting and oligonucleotide hybridization. gamma delta TCR V region expression was determined in gut biopsies and peripheral blood of 11 patients with IgAN, and the TCR V gamma and V delta repertoires were compared to those in gut and peripheral blood of 11 control individuals. gamma delta T cells in normal blood predominantly expressed V gamma 2 (V gamma 9 gene) and V delta 2 gene segments whereas those in normal gut mainly expressed V gamma 3 and V delta 3. In IgAN patients, V delta 2 was also the predominant V delta gene utilized by peripheral blood gamma delta T cells, however, we observed a predominance of V gamma 3 and reduced V gamma 2 usage by these cells. gamma delta T cells in the gut of IgAN patients mainly used V gamma 3 and V delta 1. While the gamma and delta TCR V region repertoires did not differ significantly between the peripheral blood of patients and controls, there were significant differences in V gamma and V delta repertoire expression between IgAN and control gut biopsies. V gamma 3 gene expression was significantly decreased in IgAN gut compared to control gut (P = 0.023). In addition, there was a significant decrease in V delta 3 gene expression in IgAN gut compared to control gut (P = 0.043). These findings indicate that a subpopulation of gamma delta T cells, which represent the majority of gamma delta T cells in normal gut mucosa, are significantly diminished in the gut of patients with IgAN. This suggests that a "hole" in the mucosal gamma delta T cell repertoire may play a fundamental role in contributing to the pathogenesis of IgAN.

Adult↗
PubMed1997

Potential for bilateral nephrectomy to reduce oxalate release after combined liver and kidney transplantation for primary hyperoxaluria type 1.

Primary hyperoxaluria type 1 (PH-1) is frequently associated with end stage renal failure due to urinary calculi, obstructive uropathy and interstitial deposits of calcium oxalate. The currently accepted treatment for PH-1 is liver transplantation to replace the deficient enzyme peroxisomal alanine glycoxylate aminotransferase (AGT) and a simultaneous renal transplant to restore renal function. The transplanted kidney may become significantly impaired or fail when systemic calcium oxalate is eliminated by renal excretion. The native kidneys are a major source of this oxalate. This study was undertaken to determine whether there is a difference in oxalate clearance following combined liver-kidney transplant in patients with PH-1 by comparing the effect of native kidney nephrectomy at the time of transplantation against leaving the native kidneys in situ. Regression analysis was used to compare daily urinary oxalate excretion corrected for body surface area. There was a significant reduction in urinary oxalate excretion (P < 0.05) in the patient who had undergone bilateral nephrectomy compared to the patient whose native kidneys remained in situ for the first 100 d following combined liver and kidney transplantation. No difference was observed in the serum oxalate levels between patients over the same period or in the renal function assessed by creatinine clearance corrected for body surface area. Total body oxalate load was not determined in this study. A larger study should be undertaken to examine the benefits of nephrectomy in reducing oxalate deposition in recently inserted allografts for patients with PH-1.

Adult↗
PubMed1996

Survey of haemolytic-uraemic syndrome in Queensland 1979-1995.

OBJECTIVE: To review the clinical course of haemolytic-uraemic syndrome (HUS) in children admitted to Brisbane children's hospitals between April 1979 and October 1995. DESIGN: Retrospective case survey. SETTING: Royal Children's Hospital and Mater Misericordiae Children's Hospital (the two major children's hospitals in Brisbane). SUBJECTS: All children hospitalised for HUS. OUTCOME MEASURES: Clinical and laboratory features on presentation (including typical [diarrhoea-positive, D+] or atypical [diarrhoea-negative, D-] presentation), clinical course, treatment and features on subsequent outpatient follow-up (1, 3, 6 and 12 months later), renal outcome on long term follow-up (3-16 years later). RESULTS: 55 children (aged 2 months to 13 years) were hospitalised for HUS, but no epidemic was detected. Seven children (13%) had D- presentations, including three (5%) with T-activation caused by pneumococcal pneumonia. Thrombocytopenia was more severe and prolonged in D- patients (P < 0.01). Major complications occurred only in the D+ group (one patient died, and two had recurrences). Chronic renal failure was significantly more likely in patients with prolonged oliguria or hypertension in the acute illness and proteinuria or hypertension on follow-up. CONCLUSIONS: The clinical course and outcome in childhood HUS vary greatly and D- HUS is not invariably associated with a poorer prognosis than D+ HUS. Pneumococcal-associated T-activation is an important cause of D- HUS and should be actively sought to allow for appropriate therapy.

Adolescent↗
PubMed1995

Infiltration of the kidney by alpha beta and gamma delta T cells: effect on progression in IgA nephropathy.

We have studied renal biopsies from three groups of patients to determine if alpha beta T cells or gamma delta T cells are present, and whether their presence is correlated with disease progression in IgA nephropathy (IgAN). Group one comprised thin basement membrane disease biopsies (non-immunological control, N = 7); group two were patients with IgAN and stable renal function one year following biopsy (stable, N = 7); and group three were IgAN patients with rapidly declining renal function after one year (progressive, N = 7). Immunohistochemical staining using monoclonal antibodies (CD3, TcR beta, TcR delta) and molecular studies utilizing polymerase chain reaction amplification of cDNA transcribed from biopsy RNA, with primers specific for either the alpha beta TcR or gamma delta TcR, were undertaken. On immunohistochemistry a significant increase in CD3 + cells in progressive biopsies was seen (vs. control P = 0.002, vs. stable P = 0.002). The progressive biopsies infiltrate consisted of both alpha beta TcR (vs. control P = 0.001, vs. stable P = 0.003) and gamma delta TcR cells (vs. control P = 0.01). The RNA study demonstrated an increase in TcR C alpha transcription in the progressive (vs. control P = 0.003) biopsies. Increased TcR C delta transcription was seen in the progressive group (vs. control P = 0.01, vs. stable P = 0.02). We confirm that the presence of lymphocytes in IgAN biopsies predicts progressive disease. While alpha beta T cells are found in both stable and progressive disease, the presence of gamma delta T cells is only associated with progressive IgAN.

Adult↗
PubMed1995

Distribution and role of lipopolysaccharide in the pathogenesis of acute renal proximal tubule injury.

Endotoxins (lipopolysaccharides; LPS) are known to cause multiple organ failure, including renal dysfunction. The present report elucidates LPS distribution and effect on renal proximal tubules in an attempt to gain a better understanding of the cellular mechanism underlying the pathogenesis of renal dysfunction in endotoxemia and sepsis. Rats were intravenously treated with biotin-linked or regular Escherichia coli (0111:B4) LPS (3 mg/kg) and sacrificed at different times. Kidneys were retrieved and examined for LPS localization, tubular permeability, ultracytochemical alterations, leukocyte sequestration, and ICAM-1 expression. The functional impact of endotoxemia was also assessed by monitoring the changes in urine levels of glucose in timed collections up to 6 h. LPS was localized on the plasma membranes of the apical microvilli, the labyrinth of the lateral intercellular spaces, in various organelles of epithelial cells, and in the endothelial cells of the peritubular capillaries. LPS caused structural damage and calcium accumulation in the mitochondria, leakage of tight junctions, widening of the basolateral intercellular spaces, intracellular and extracellular edema, leukocyte margination and accumulation, vascular expression of ICAM-1, and decrease of plasma membrane and mitochondrial Ca2(+)-ATPase. Physiological study showed that both urine volume and glucose were greatly increased after LPS infusion. The pathological alterations in the proximal tubules may directly contribute to the reduction in the reabsorption ability of the proximal tubules.

Acute Disease↗