Artificial intelligence in ovarian cancer histopathology: a systematic review

This study evaluates the quality of published research using artificial intelligence (AI) for ovarian cancer diagnosis or prognosis using histopathology data. A systematic search of PubMed, Scopus, Web of Science, Cochrane CENTRAL, and WHO-ICTRP was conducted up to May 19, 2023. Inclusion criteria required that AI was used for prognostic or diagnostic inferences in human ovarian cancer histopathology images. Risk of bias was assessed using PROBAST. Information about each model was tabulated and summary statistics were reported. The study was registered on PROSPERO (CRD42022334730) and PRISMA 2020 reporting guidelines were followed. Searches identified 1573 records, of which 45 were eligible for inclusion. These studies contained 80 models of interest, including 37 diagnostic models, 22 prognostic models, and 21 other diagnostically relevant models. Common tasks included treatment response prediction (11/80), malignancy status classification (10/80), stain quantification (9/80), and histological subtyping (7/80). Models were developed using 1-1375 histopathology slides from 1-776 ovarian cancer patients. A high or unclear risk of bias was found in all studies, most frequently due to limited analysis and incomplete reporting regarding participant recruitment. Limited research has been conducted on the application of AI to histopathology images for diagnostic or prognostic purposes in ovarian cancer, and none of the models have been demonstrated to be ready for real-world implementation. Key aspects to accelerate clinical translation include transparent and comprehensive reporting of data provenance and modelling approaches, and improved quantitative evaluation using cross-validation and external validations. This work was funded by the Engineering and Physical Sciences Research Council.

AuguR: A Scalable Open-Source Interactive Web Application for Routinely Collected Data

Most data collected by hospitals as a consequence of the delivery of routine care is not utilised for analytics or organisational intelligence. This project aims to develop tools to enhance the utilisation of routinely collected cancer data within hospitals across England. This was achieved by developing a web application using open source tools to provide health care professionals and hospital managers with easy to use, interactive analytics for cancer data. The application uses data items hospitals in England are mandated to collect as part of the Cancer Outcomes and Services Dataset (COSD), to provide clinical insight into survival outcomes, population distributions, service demands, waiting times, geographical case distributions and treatment information in real-time or near real-time. Development was guided by end user needs through the use of panels of clinical and non-clinical end users.

The Pitfalls of Using Open Data to Develop Deep Learning Solutions for COVID-19 Detection in Chest X-Rays

Since the emergence of COVID-19, deep learning models have been developed to identify COVID-19 from chest X-rays. With little to no direct access to hospital data, the AI community relies heavily on public data comprising numerous data sources. Model performance results have been exceptional when training and testing on open-source data, surpassing the reported capabilities of AI in pneumonia-detection prior to the COVID-19 outbreak. In this study impactful models are trained on a widely used open-source data and tested on an external test set and a hospital dataset, for the task of classifying chest X-rays into one of three classes: COVID-19, non-COVID pneumonia and no-pneumonia. Classification performance of the models investigated is evaluated through ROC curves, confusion matrices and standard classification metrics. Explainability modules are implemented to explore the image features most important to classification. Data analysis and model evalutions show that the popular open-source dataset COVIDx is not representative of the real clinical problem and that results from testing on this are inflated. Dependence on open-source data can leave models vulnerable to bias and confounding variables, requiring careful analysis to develop clinically useful/viable AI tools for COVID-19 detection in chest X-rays.

Collection of cancer Patient Reported Outcome Measures (PROMS) to link with primary and secondary electronic care records to understand and improve long term cancer outcomes: A protocol paper

Introduction

More people are living with and beyond a cancer diagnosis. There is limited understanding of the long-term effects of cancer and cancer treatment on quality of life and personal and household finances when compared to people without cancer. In a separate protocol we have proposed to link de-identified data from electronic primary care and hospital records for a large population of cancer survivors and matched controls. In this current protocol, we propose the linkage of Patient Reported Outcomes Measures data to the above data for a subset of this population. The aim of this study is to investigate the full impact of living with and beyond a cancer diagnosis compared to age and gender matched controls. A secondary aim is to test the feasibility of the collection of Patient Reported Outcomes Measures (PROMS) data and the linkage procedures of the PROMs data to electronic health records data.

Materials and methods

This is a cross-sectional study, aiming to recruit participants treated at the Leeds Teaching Hospitals National Health Service Trust. Eligible patients will be cancer survivors at around 5 years post-diagnosis (breast, colorectal and ovarian cancer) and non-cancer patient matched controls attending dermatology out-patient clinics. They will be identified by running a query on the Leeds Teaching Hospitals Trust patient records system. Approximately 6000 patients (2000 cases and 4000 controls) will be invited to participate via post. Participants will be invited to complete PROMs assessing factors such as quality of life and finances, which can be completed on paper or online (surveys includes established instruments, and bespoke instruments (demographics, financial costs). This PROMs data will then be linked to routinely collected de-identified data from patient’s electronic primary care and hospital records.

Discussion

This innovative work aims to create a truly ‘comprehensive patient record’ to provide a broad picture of what happens to cancer patients across their cancer pathway, and the long-term impact of cancer treatment. Comparisons can be made between the cases and controls, to identify the aspects of life that has had the greatest impact following a cancer diagnosis. The feasibility of linking PROMs data to electronic health records can also be assessed. This work can inform future support offered to people living with and beyond a cancer diagnosis, clinical practice, and future research methodologies.

A data flow process for confidential data and its application in a health research project

BACKGROUND

The use of linked healthcare data in research has the potential to make major contributions to knowledge generation and service improvement. However, using healthcare data for secondary purposes raises legal and ethical concerns relating to confidentiality, privacy and data protection rights. Using a linkage and anonymisation approach that processes data lawfully and in line with ethical best practice to create an anonymous (non-personal) dataset can address these concerns, yet there is no set approach for defining all of the steps involved in such data flow end-to-end. We aimed to define such an approach with clear steps for dataset creation, and to describe its utilisation in a case study linking healthcare data.

METHODS

We developed a data flow protocol that generates pseudonymous datasets that can be reversibly linked, or irreversibly linked to form an anonymous research dataset. It was designed and implemented by the Comprehensive Patient Records (CPR) study in Leeds, UK.

RESULTS

We defined a clear approach that received ethico-legal approval for use in creating an anonymous research dataset. Our approach used individual-level linkage through a mechanism that is not computer-intensive and was rendered irreversible to both data providers and processors. We successfully applied it in the CPR study to hospital and general practice and community electronic health record data from two providers, along with patient reported outcomes, for 365,193 patients. The resultant anonymous research dataset is available via DATA-CAN, the Health Data Research Hub for Cancer in the UK.

CONCLUSIONS

Through ethical, legal and academic review, we believe that we contribute a defined approach that represents a framework that exceeds current minimum standards for effective pseudonymisation and anonymisation. This paper describes our methods and provides supporting information to facilitate the use of this approach in research.

Observational study investigating Tolerance Of Anticancer Systemic Therapy In the Elderly (TOASTIE): a protocol

INTRODUCTION

The number of older adults diagnosed with cancer is increasing. Older adults are more likely to have pre-existing frailty, which is associated with greater chemotherapy-related toxicity. Early identification of those at risk of toxicity is important to reduce patient morbidity and mortality. Current chemotherapy toxicity prediction tools including the Cancer and Ageing Research Group (CARG) tool exist but are not in routine clinical use and have not been prospectively validated in a UK population. This study is the first prospective study to investigate the CARG tool in a UK population with cancer.

METHODS AND ANALYSIS

Tolerance Of Anticancer Systemic Therapy In the Elderly is a prospective observational study of patients, aged ≥65 years, commencing first-line (any indication) chemotherapy for a solid-organ malignancy. Patients receiving other systemic anticancer agents or radiotherapy will be excluded. The primary objective will be to validate the ability of the CARG score to predict grade 3+ toxicity in this population. Secondary objectives include describing the feasibility of screening for frailty, as well as the prevalance of frailty in this population and assessing patient and clinician perception of chemotherapy toxicity risk. 500 patients will be recruited over a two year period. Baseline assessments will be recorded. At the end of the 6-month follow-up period, toxicity data will be retrospectively collected. A descriptive analysis of the recruited population will be performed. The validity of the CARG model will be analysed using receiver-operating characteristic curves and calculation of the area under the curve (c-statistic).

ETHICS AND DISSEMINATION

The study has received ethical approval from the East of Scotland Research Ethics Service 20/ES/0114. Results will be reported in peer-reviewed scientific journals and disseminated to patient organisations and media.

P14.70 BMScope: A systematic mapping review of brain/leptomeningeal metastasis clinical studies from 2010 to 2020

BACKGROUND

Brain metastasis (BM) and leptomeningeal disease (LMD) are typified by a poor prognosis and are an area of unmet clinical need. Historically, patients with central nervous system (CNS) disease have been excluded from systemic therapy clinical trials, particularly with active/leptomeningeal disease. However, increasing prevalence of CNS metastasis is leading to greater interest in BM/LMD. We performed a descriptive analysis of clinical studies investigating BM/LMD management, published between Jan 2010 to Mar 2020.

METHODS

A comprehensive, customised search strategy was devised for 12 online bibliographic databases, using the following concepts: “clinical study”, “brain metastasis”, “leptomeningeal disease”, “intervention”, “patient-related outcome”. Double screening for inclusion/exclusion was performed on the Rayyan QCRI web application. Published abstracts were also screened for inclusion from ASCO, ESMO, SNO and EANO between 2015–2020. Following full text screening, conflicts were resolved by consensus and data were extracted using an online standardised tool. Data analysis and data visualisation were performed on the R statistical package.

RESULTS

Overall, 33118 published studies were double screened; 2632 full publications and 628 abstracts were included. Of these, 14.7% reported on unique interventional clinical trials (phase 2 = 267; phase 3 = 80). More than three times the number of clinical trials investigating systemic agents as the sole therapy for BM/LMD were published in Q1 2020 compared to the whole of 2010 (16 vs 5). 42.5% of clinical trials employed a form of local therapy (brain targeted radiotherapy or neurosurgery). Studies reported on patients with BM (n = 2738), LMD (n = 110) or both (n = 119). The majority of studies were performed in North America, Europe or East Asia (88.5% vs 11.5% rest of the world). The top 3 nations involved in published studies were the USA (n = 1155), China (n = 351) and Germany (n = 334). Network analysis demonstrated increasing links between countries. In line with expected BM prevalence, the main tumour sites studied were lung (23.4%), gastrointestinal (17.5%), breast (15%) and melanoma (12.5%). A rising trend of published BM/LMD studies over time was noted, with 83 observational studies/10 clinical trials in 2010 vs. 454 observational studies/80 clinical trials in 2019.

CONCLUSION

These findings demonstrate that over the last decade there has been a growth in BM/LMD research; likely reflecting an increasing disease prevalence, availability of novel and potentially CNS active agents, as well as more advanced local therapy modalities. BM/LMD clinical research is dominated by a few geographical regions and nations; however, there is an apparent shift to more international collaboration. This comprehensive mapping exercise will enable targeted systematic reviews of the existing evidence base on BM/LMD management.

Current Treatment and Outcomes Benchmark for Locally Advanced or Metastatic Urothelial Cancer From a Large UK-Based Single Centre

Objectives: To characterize treatment patterns and survival outcomes for patients with locally advanced or metastatic malignancy of the urothelial tract during a period immediately preceding the widespread use of immune checkpoint inhibitors in the UK.

Patients and Methods: We retrospectively examined the electronic case notes of patients attending the Leeds Cancer Center, UK with locally advanced or metastatic urothelial carcinoma, receiving chemotherapy between January 2003 and March 2017. Patient characteristics, treatment patterns, and outcomes were collected. Summary and descriptive statistics were calculated for categorical and continuous variables as appropriate. The Kaplan–Meier method was used to estimate median survival and Cox regression proportional hazards model was used to explore relationships between clinical variables and outcome.

Results: Two hundred and sixteen patients made up the study cohort, with a median age of 66 years (range: 35–83) and 72.7% being male. First-line treatment consisted of either a cisplatin- (44%) or carboplatin-based regimen (48%) in the majority of patients. Twenty seven percent of patients received a second-line of treatment (most commonly single-agent paclitaxel) following a first-line platinum containing regimen. Grade 4 neutropenia was observed in 19 and 27% of those treated with a first-line cisplatin- and carboplatin-based regimen, respectively. The median overall survival (mOS) of the study cohort was estimated to be 16.2 months (IQR: 10.6–28.3 months). Receipt by patients of cisplatin-based chemotherapy was associated with a longer mOS and this association persisted when survival analysis was adjusted for age, sex, performance status and presence of distant metastases.

Conclusions: This study provides a useful benchmark for outcomes achieved in a real-world setting for patients with locally advanced or metastatic UC treated with chemotherapy in the immediate pre-immunotherapy era.

Hepatitis C in liver transplantation: preliminary study of prognostic factors

At the University of Miami liver transplantation for chronic liver disease in HCV-positive patients has shown good results, with a 92% patients survival rate (follow up 8 to 57 months, median 21). None the less, we found that a large number of patients are expected to develop serious histological graft damage and may need retransplantation, which may place a further strain on the already scarce donor resources. We have conducted a preliminary investigation on the importance of parameters which may correlate with the prognosis of HCV grafts. We found no impact of HLA match or typing. An interesting hypothesis, which deserves further investigation, is that some HCV strains could be more virulent than others and play a role as an independent risk factor. We have identified six strains among our patients and the BK serotype shows a trend to be associated with a worse outcome. We have found that patients developing and maintaining higher liver enzyme levels (ALT and GGT) after transplant and those with higher levels of viremia may be at risk to develop serious damage to their grafts.

Levels of mycophenolic acid and its glucuronide derivative in the plasma of liver, small bowel and kidney transplant patients receiving tacrolimus and cellcept combination therapy

In order to help assess the usefulness of mycophenolate mofetil (MMF) as an immunosuppressive agent in recipients of organs other than kidneys, we measured the trough levels of the active metabolite of MMF, mycophenolic acid (MPA), and its inactive glucuronide derivative (MPAG), in the plasma of liver (n = 83) and small bowel transplant patients (n = 15) receiving MMF in combination with tacrolimus. These levels were compared with a group of renal transplant patients (n = 25) receiving the same drug regimen. All patient groups were otherwise comparable except the small bowel patient group which contained more pediatric patients (average age 18.7 +/- 3.9 years), and, therefore, received a higher average drug dose (in mg/kg). Despite this, these patients displayed the lowest levels of MPA of any group (0.39 +/- 0.08 microg/ml, P < 0.001 vs. 1.10 +/- 0.17 microg/ml for liver transplant patients, P < 0.001 or 2.46 +/- 0.37 microg/ml for renal transplant patients, P < 0.001). There were no statistically significant differences in MPAG levels between any of the groups. Although preliminary, these data demonstrate significant transplanted organ-specific differences in MMF pharmacology and/or bioavailability, and suggest the need for separate evaluation of MMF dosing for each transplant type.

Evidence that tacrolimus augments the bioavailability of mycophenolate mofetil through the inhibition of mycophenolic acid glucuronidation

We previously reported an unexpected augmentation of mycophenolic acid (MPA) levels (trough and AUC0-12) in patients receiving mycophenolate mofetil (MMF) in combination with tacrolimus versus patients receiving the same dose of MMF in combination with cyclosporin A (CsA). This finding was accompanied by a corresponding reduction of the inactive glucuronide metabolite of MPA (MPAG) in patients, suggesting that tacrolimus may effect the conversion of MPA to MPAG by the enzyme UDP-glucuronosyltransferase (UDPGT). To investigate this possibility directly, UDPGT was extracted from human liver and kidney tissue and its activity was characterized using MPA as a substrate in vitro, assessing the conversion of MPA to MPAG using analysis by high-performance liquid chromatography. With crude microsomal preparations, amounts of UDPGT at least 100 times higher in specific activity (i.e., units to milligrams of protein) could be extracted per gram of tissue from kidney as opposed to liver. This result did not appear to be related to the coextraction of a liver-specific UDPGT inhibitor because initial enzyme kinetic values (Vmax and km) were identical for kidney and liver extracts, and further purification of the liver enzyme did not enhance activity (as is seen when inhibitors are removed during purification). With further UDPGT purification (approximately 200-fold) from kidney extracts using a combination of ammonium sulfate precipitation, followed by anion exchange, hydroxyapatite, and size exclusion chromatography, the enzyme was more than 80% pure when assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Initial enzyme kinetic analysis of this purified product showed a km value for MPA of 35.4+/-5.7 microg/mL and a Vmax of 2.87+/-0.31 MPAG produced per hour (n = 7). The addition of clinically relevant concentrations of CsA (200-1,000 ng/mL) or tacrolimus (10-25 ng/mL) resulted in a dose-dependent inhibition of the UDPGT enzyme by both agents with tacrolimus, which was approximately 60-fold more efficient as an inhibitor. The calculated inhibition constants (KI) of tacrolimus and CsA for the purified UDPGT were 27.3+/-5.6 ng/ml and 2,518+/-1473 ng/ml. respectively. Both agents displayed an inhibition profile characteristic of a competitive inhibitor (substrate) that could be demonstrated in a reciprocal experiment with CsA as a substrate, but not with tacrolimus. This finding suggested that the significantly more efficient inhibition of UDPGT by tacrolimus may occur by a more complicated mechanism that is yet to be determined.

Continuing observations on the regulatory effects of donor-specific bone marrow cell infusions and chimerism in kidney transplant recipients

BACKGROUND

Continued follow-up of a series of donor bone marrow cell (DBMC)-infused first cadaver renal transplant recipients is described (n=58), now at a 36-month actuarial time point postoperatively. Serial polymerase chain reaction-flow cytometry (PCR-Flow) and cellular immune assays of iliac crest bone marrow aspirates and peripheral blood have begun to be compared with concomitantly transplanted recipients of living-related donor (LRD) kidneys and donor marrow infusions given the same immunosuppressive regimen (n=16). There have also been comparisons (36 months) with 188 controls transplanted concomitantly, i.e., recipients of first cadaver kidney transplants, who did not receive bone marrow.

METHODS

Each group was given equivalent immunosuppressive regimens of OKT3 anti-T cell induction and maintenance tacrolimus, mycophenolate mofetil, and methylprednisolone. Actuarial patient and graft survival have been 96% and 93%, respectively, in the controls and 91% and 91%, respectively, in the DBMC-infused recipients. Trough levels of tacrolimus were significantly lower in the DBMC-infused group.

RESULTS

In PCR-Flow measurements, in peripheral blood up to 6 months postoperatively, there were higher levels of chimerism, i.e., in the total number of donor cells, as well as the donor CD3+ and CD34+ subsets in the LRD recipients administered DBMC infusions, compared with cadaver DBMC recipients, supporting the notion of a positive effect of histocompatibility on chimerism levels. In PCR-Flow measurements of recipient iliac crest bone marrow aspirates as in previous studies on peripheral blood, early acute rejection episodes (<1 month) were found to be associated with a later (6-14 months) decrease in donor cell lineage chimerism. However, a trend toward recovery of chimeric levels occurred by 21-28 months in a second iliac crest marrow aspirate 1 year after the first aspirate in the DBMC-infused recipients who experienced such early rejection episodes. This was in contrast to the controls in whom there were sustained low levels of iliac crest bone marrow chimerism at both the earlier and later intervals (i.e., no chimeric recovery), with 17/183 surviving controls progressing into chronic rejection. This has not yet been seen in the DBMC-infused group (0/54). In in vitro observations on cellular immune reactivity at 1 year postoperatively, decreased peripheral blood lymphocyte proliferative reactions were seen in response to phytohemagglutinin and Staph-A mitogens, as well as to cytomegalovirus and Epstein-Barr viral protein antigens in the DBMC-infused group versus the controls. Chronic immunosuppression did not seem to effect a vigorous in vitro inhibitory (regulatory) activity of bone marrow taken from these transplant recipients 2 years postoperatively in mixed lymphocyte culture and cell-mediated lympholysis reactions, using allogeneic responding cells from "normal" laboratory volunteers. Autologous peripheral blood lymphoproliferative responses to phytohemagglutinin and Staph-A mitogens, as well as to cytomegalovirus and Epstein-Barr virus protein antigens, were also regulated by either organ donor (non-immunosuppressed) bone marrow cells or by transplant recipient (immunosuppressed) bone marrow cells. What appeared to be disparate between the DBMC-infused and control groups (both immunosuppressed) was the trend for the (autologous) bone marrow suppressive effect on antiviral lymphoproliferative responses, to be stronger in the DBMC-infused group, who also had significantly (>one order of magnitude) higher levels of chimerism (P=0.01).

CONCLUSIONS

It is concluded that the establishment of a chimeric state in DBMC-infused recipients, albeit of relatively low magnitude (approximately 1% at 2 years in recipient iliac crest bone marrow), has had a definite regulatory effect on immune responses. These results, therefore, add weight to the "causal" horn of the dilemma as to whether donor cell chimerism is a cause or an effect of

Cellular immune responses of human cadaver donor bone marrow cells and their susceptibility to commonly used immunosuppressive drugs in transplantation

BACKGROUND

The cascade of immunological effects brought about by donor bone marrow cell (DBMC) infusions in human organ transplantation, especially in the context of continuous pharmacologic immunosuppression, is not fully understood. Yet, in inbred rodents and even primates, administration of specific bone marrow cells has caused a state of acquired immunologic tolerance.

METHODS

In vitro mixed lymphocyte culture (MLC) and cell-mediated lympholysis (CML) culture systems were used to compare the responding and regulatory properties of DBMC and individual bone marrow cell subsets versus spleen cells in the presence or absence of pharmacologic immunosuppression.

RESULTS

In the absence of immunosuppressive drugs, the DBMC proliferated in MLC and in response to phytohemagglutinin, but to a lower magnitude than donor spleen cells. In CML assays, DBMC failed to function as cytotoxic cells. Removal of both CD3+ and CD34+ cells together (not just singly) had to occur for complete abrogation of the proliferative response of DBMC evoked in the presence of allogeneic stimulating cells. Testing several experimental variables using flow cytometric analysis led to the conclusion that when purified DBMC CD34+ cells were placed in coculture with irradiated allogeneic peripheral blood mononuclear cells, such CD34+ cells give rise both to CD3- TCRalphabeta+ as well as to dimly staining CD3+ TCRalphabeta+ cells. Low pharmacologic concentrations of tacrolimus/cyclosporine (CsA) and mycophenolic acid (MPA) singly or in combination had no effect on the spontaneous proliferation of DBMC and had significantly less inhibitory activity on MLC responses of DBMC and its purified CD3+ or CD34+ subpopulations, compared with the responses of spleen cells. Moreover, the previously described regulatory effects of DBMC on the MLC responses of peripheral blood or splenic responding cells were not inhibited by these immunosuppressive drugs.

CONCLUSIONS

Taken together, these results support the notion that in vitro DBMC subpopulations, which proliferate as responding cells in co-culture with x-irradiated allogeneic cells and which cause regulatory effects when added as a third component to MLC reactions, seem to be culture-generated lymphoid cell lineage(s) progeny of CD34+ cells. This possibly includes unique CD3+ "primitive" (dimly staining) T cells, which are not as inhibited in their function by tacrolimus/CsA and MPA, as are postthymic (splenic) T cells.

Successful treatment of esophageal achalasia with laparoscopic Heller myotomy and Toupet fundoplication

BACKGROUND

Recently, investigators have reported the use of endoscopic myotomy in the treatment of esophageal achalasia. As with the open operation, considerable disagreement exists regarding the appropriate length of the myotomy and the need for a concomitant antireflux procedure.

METHODS

Patients presenting with symptomatic achalasia between 1993 and 1997 were included in this prospective study. Preoperative studies included barium upper gastrointestinal study, endoscopy, and esophageal manometry. Laparoscopic myotomy was completed in all 20 patients; 18 had concomitant Toupet fundoplication.

RESULTS

Operative times ranged from 95 to 345 minutes (mean 216). Blood loss ranged from 50 to 300 cc (mean 100 cc). There were 7 minor complications (5 mucosal injuries repaired laparoscopically, 1 bile leak and 1 splenic capsular tear). Nine patients began a liquid diet on the first day postoperatively; 19 were tolerating liquids by postoperative day 3. Hospital stay ranged from 2 to 20 days (mean 5). Eighteen patients had complete relief of dysphagia, with less than one reflux episode per month. One individual continues to have mild persistent solid food dysphagia. Another patient initially did well but subsequently developed mild recurrent dysphagia and reflux. One patient required laparoscopic take-down of the wrap because of recurrent dysphagia and now has no problems swallowing, but does complain of mild reflux. Two other patients also have mild reflux, 1 of whom did not undergo fundoplication.

CONCLUSIONS

Laparoscopic Heller myotomy can be performed safely with excellent results in patients with achalasia. Adding a partial fundoplication appears to help control postoperative symptoms of reflux. This procedure should be considered the procedure of choice in patients with symptomatic esophageal achalasia.

Unexpected augmentation of mycophenolic acid pharmacokinetics in renal transplant patients receiving tacrolimus and mycophenolate mofetil in combination therapy, and analogous in vitro findings

Mycophenolate mofetil (MMF) a potent immunosuppressive agent, has recently been approved for clinical use (CellCept) in renal transplant patients in combination with cyclosporine (CsA). With the expanded use of tacrolimus (Prograf) as well in renal transplant patients, there is a lack of pharmacokinetic studies clarifying drug interactions between the three agents. A pharmacokinetic study was performed on 18 stable renal transplant patients receiving MMF and tacrolimus together, and four control groups, one receiving tacrolimus alone, two receiving CsA, in combination with MMF (1.0 or 1.5 g bid), and one receiving CsA microemulsion (Neoral). Area-under-the-curve values were calculated for each drug to assess if there was a reciprocal effect on the respective bioavailability of each. In vitro, the immunosuppressive effect of trough level plasma from each patient group was studied using mixed lymphocyte culture (MLC), as well as MLC reactions spiked with various combinations of each drug. There was a minimal effect of MMF on tacrolimus pharmacokinetics. However, patients receiving tacrolimus and MMF displayed significantly higher levels (Cmin and area under the curve) of mycophenolic acid (MPA) than those receiving CsA (Sandimmune or Neoral) and the same dose of MMF (50.2 +/- 16.5 vs 32.1 +/- 16.7 micrograms h/ml AUC, p < 0.02). Equivalent MPA levels could be attained in patients receiving CsA if the MMF dose was increased by 50% (1.5 g bid). There were also significantly lower levels of the glucuronide metabolite of MPA (MPAG) (755 +/- 280 vs 1230 +/- 250 micrograms h/ml AUC, p = 0.02), suggesting a specific inhibition (either direct or indirect) of the conversion of MPA to MPAG in tacrolimus patients, as opposed to those receiving CsA. For each drug combination, there was a positive correlation between the plasma immunosuppressive effect seen in MLC assays and the MMF dose. In addition, trough plasma from patients receiving tacrolimus and MMF was significantly more MLC inhibitory than from those receiving CsA or CsA microemulsion and equivalent-dose MMF. Culture media containing MPA and tacrolimus equal to clinical therapeutic trough concentrations (10 ng/ml) were significantly more MLC inhibitory than CsA at equivalent clinical therapeutic trough concentrations (200 ng/ml) with equivalent MPA levels. These studies in renal transplant patients suggest that tacrolimus in combination with MMF may result in a greater degree of immunosuppression than may be anticipated.

Dipeptidyl peptidase IV (CD26) activity in human alloreactive T cell subsets varies with the stage of differentiation and activation status

Dipeptidyl peptidase IV (DPP IV), also known as CD26, is a transmembrane serine aminopeptidase which has an ontogenically related expression on T cells and participates on several immunological functions. CD26 appears to play an important role in alloimmunity during host T cell activation subsequent to alloantigen encounter and is a way by which effector T cells traverse graft endothelial barriers. In order to help to elucidate the role of the CD26 molecule in alloimmune responses, DPP IV activity and CD26 antigenic expression were assessed during the initial phases of completely MHC-disparate human mixed lymphocyte reactions (MLRs) and in several long-term alloreactive T cell clones. Our methods involved the use of a rhodamine-110-conjugated dipeptide substrate specific for DPP IV in two-colour cytofluorographic analysis that allowed stimultaneous lineage marker evaluation. Polyclonal populations of alloreactive CD4 and CD8 T cells contained DPP IV activity at 1 and 10 min of incubation that was variably elevated from resting T cells with the enzyme activity confined to CD26+ cells. T cell clones derived from MLRs were established with IL-2 supplementation and alloantigen restimulation and had reduced CD62L expression with functional specificity to the stimulating MHC. While CD26 expression remained stable, DPP IV activity was variable in the alloreactive T cell clones, with enzyme function in the latter appearing to coincide with the timing of alloantigen restimulation. These studies demonstrate that DPP IV activity varies among phenotypically distinct alloreactive T cell subsets and appears to be altered with the activation status of the effector cells. These findings raise the potential of a role for CD26/DPP IV in the generation of specific alloimmunity. With this methodology, it may be possible to reveal whether specific alterations in the activity of this molecule in T cell populations promote graft acceptance and to determine the molecular requirements for these changes.

The immune reactivity role of HCV-induced liver infiltrating lymphocytes in hepatocellular damage

Liver infiltrating lymphocytes (LIL) were isolated from HCV-positive (+) and HCV-negative (-) end-stage livers. Phenotypic analysis and functional studies using proliferative and lymphocytotoxic assays were performed with the isolated LIL. Two CD3+ lymphocyte populations were found in LIL using FITC anti-CD3 monoclonal antibodies (mAb). One was a bright fluorescence intensity population (as in PBL), and the other dim. We calculated the number of FITC-anti-CD3 mAbs bound per lymphocyte on PBL and LIL and found 80,040 +/- 4628 and 39,615 +/- 3932, respectively. Therefore, HCV+ and HCV- patient PBL contained approximately twice the number of CD3 molecules per cell than patient CD3+ LIL. LIL also contained approximately a threefold higher concentration of TCR alpha beta +, CD4-CD8-, and CD56,16 (NK) cells than the patient PBL. Thus, a major subset of LIL is phenotypically similar to mouse NK1.1+ "intermediate" T cells. LIL freshly isolated from HCV+ livers exhibited weak CTL activity against EBV- or Con A-transformed lymphoblast targets infected with vaccinia-HCV recombinant virus (rHCV) or primary hepatocyte cultured cells. However, after in vitro coculture of LIL with rHCV, these cells developed a strong cytotoxicity for the above targets. In contrast, LIL from HCV- livers were not cytotoxic against the same targets. Histochemical studies (in situ) demonstrated that these hepatocytes express CD95, and stains demonstrated apoptosis. The HCV+ hepatocytes also express class I MHC molecules and ICAM-1. The addition of mAb specific for these adhesion molecules inhibited CML activity. Short-term cultured hepatocytes (targets) from HCV+ and HCV- patients produced low levels of cytokines IL-1 beta, IL-2, IL-6, TNF alpha, and IFN-gamma but a high level of IL-8. It is speculated that LIL expressing reduced numbers of CD3 molecules may even function as immune regulators as proposed for intermediate T cells in mice.

The effects of chimeric cells following donor bone marrow infusions as detected by PCR-flow assays in kidney transplant recipients

40 recipients of first cadaver kidney transplants were given perioperative donor vertebral bone marrow infusions (DBMC), compared with 100 controls who did not receive donor bone marrow. The immunosuppressive regimen included OKT3, Tacrolimus, and steroid maintenance therapy, and, in some patients, newly introduced mycophenolate mofetil. This report describes the 24-mo actuarial follow-up and several immunological monitoring studies including sequential measurements of donor bone marrow lineage subset chimerism by the recently reported PCR-flow assay. This is a sensitive in situ PCR detection system for donor versus recipient histocompatibility genes as well as cell surface CD epitope markers using flow cytometry. The results indicate (a) the stabilization of the donor CD3+ and CD34+ cells in recipient peripheral blood at levels below 1% between 6 mo and 1 yr postoperatively, with a 10-fold higher level of donor cell chimerism of these lineages in recipient iliac crest marrow; (b) significantly lower levels of chimerism in peripheral blood up to 6 mo postoperatively in patients who had early acute (reversible) rejection episodes compared with those who did not; (c) a higher degree of chimerism seen in patients who were class II MHC HLA DR identical with their donors; (d) the identification of a high proportion of the donor bone marrow derived CD3 dimly staining subset of T cells (to which regulatory functions have been ascribed) in recipient peripheral blood and especially in recipient bone marrow; and (e) an unexpectedly increased susceptibility to clinically significant infections (primarily viral), and even death in the DBMC-infused group, compared with controls, but no graft losses because of rejection in the DBMC-infused group. Mixed lymphocyte culture assays showed a trend toward a greater number of nonspecifically low reactors in the DBMC group, as well as a greater number of nonspecifically high reactors in the controls (P = 0.058). The autologous mixed lymphocyte reaction also indicated a trend towards nonspecific immune activation in the DBMC group. Finally, anti-cytomegaloviral IgG antibody reactivity was significantly inhibited in the DBMC group 4-6 mo postoperatively (P = < 0.05). In the controls, there were no donor cell lineages detected by PCR-flow in the peripheral blood. These rather unexpected findings, indicating a more depressed cellular and humoral immune capacity in the DBMC cadaver kidney transplant recipients in this relatively early follow-up period, are discussed relevant to chimerism, MHC restriction, and suppressor activity brought about by specialized DBMC subsets, which still need to be defined.

An assessment of the effects of cadaver donor bone marrow on kidney allograft recipient blood cell chimerism by a novel technique combining PCR and flow cytometry

A new technique, the PCR-flow assay is described that has allowed for the serial identification and quantitation of discrete mononuclear cell subsets of donor (or recipient) bone marrow derived cells in cadaver kidney transplant recipients infused postoperatively with donor vertebral body bone marrow cells. With fixed permeabilized cells in flow cytometry the amplification power of the polymerase chain reaction (PCR), using fluorescent-labeled primers to identify single copy HLA class II DRbeta1 genes of either donor or recipient origin, is combined with multi-color fluorochrome-labeled CD epitope-specific monoclonal antibodies. The details of the methodology are described; these support the utility of the assay. Initial observations were made on the chimeric makeup of the peripheral blood as well as iliac crest bone marrow between six months and one year posttransplantation in recipients serially followed weekly and then monthly, concomitantly compared with a control group of stable kidney transplant recipients using similar therapeutic protocols, who did not receive cadaver bone marrow. Several findings are of note. In 14 recipients of two bone marrow infusions totalling a mean of 6.29+/-2.18x10(10) cells, donor CD34 positive (+) (immature) cells were fourteen times as numerous in peripheral blood six months postoperatively as in six recipients given half as many bone marrow cells in one infusion (averaging 3.02+/-0.5x10(10)). These donor CD34+ cells unexpectedly averaged 36+/-7% of the total (donor plus recipient) CD34+ subset counted. Moreover, iliac crest bone marrow aspirates contained an average of thirteen times this number of CD34+ cells than in the peripheral blood, supporting the notion of engraftment. Of additional interest, between six months and one year posttransplant although no donor cells could be detected in peripheral blood of the controls there was an identifiable presence of donor CD34+ cells in their iliac crest bone marrow, albeit 10-fold less than the marrow-infused patients. In the clinical follow-up, although there were three unrelated mortalities, there were no additional kidney losses with current serum creatinine concentrations averaging 1.3+/-0.06 mg/dl. In conclusion, the PCR-flow assay presents the possibility of identifying discrete subsets of donor or recipient cells that may have an immunoregulatory function.

A prospective study of hepatitis C virus infection in renal allograft recipients

Hepatitis C virus (HCV) is the predominant cause of posttransplant non-A, non-B hepatitis among renal allograft recipients. Prior studies evaluating the impact of HCV in kidney transplantation have been retrospective in design and based largely on changes in serum transaminases. We studied a group of HCV-infected end-stage renal disease patients prospectively with pretransplant liver biopsies and close virologic and biochemical follow-up posttransplant. Fourteen patients have been followed a mean of 11.6 +/- 5.6 months posttransplant (range, 5-21 months). Six had changes of chronic hepatitis on pretransplant liver biopsy while 8 showed only mild histologic abnormalities. Circulating viral titers increased several-fold over baseline levels during posttransplant follow-up. Viral replication was particularly enhanced immediately following a course of antilymphocyte therapy. Although all patients showed a 2-3 fold increase in alanine aminotransferase (ALT) following transplantation, there were no association noted between pretransplant liver histology, the use of FK506 and/or cyclosporine-based immunosuppression, and the magnitude of ALT change posttransplant. The only clinical outcome found to differ significantly was a higher incidence of cytomegalovirus infection among patients with chronic hepatitis. All patients are alive with functioning grafts. There have been no episodes of fulmiinant or subfulminant liver failure. We conclude that HCV-infected patients can be safely transplanted with excellent short-term follow-up. Continued monitoring with sequential liver biopsies will be needed to define the long-term course of HCV infection in an immuno-suppressed population.

Longitudinal induced IL-2 mRNA monitoring in renal transplant patients immunosuppressed with cyclosporine and in unmodified canine renal transplant rejection

Immune monitoring of transplant patients to define optimal immunosuppression continues to be important, as rejection occurs despite adjustment of dosaging of CsA or even FK506 to achieve "therapeutic-range" blood levels. Because CsA is known to inhibit upregulation of IL-2 mRNA transcription, we prospectively sequentially measured (induced) IL-2 mRNA in PHA-stimulated PBMC cultures from transplant recipients of kidneys from living-related donors (n = 15) using a quantitative PCR assay, with a potential 24-hour turnaround time, to define immunologic events in real time. Reproducible individual patient sensitivity or refractoriness to CsA was determined pretransplant, by adding a range of CsA concentrations to the PBMC cultures and constructing induced IL-2 mRNA regression inhibition curves. However, this was not predictive of rejection episodes, but did correlate well with individual differences in IL-2 mRNA levels posttransplant, despite similar maintenance trough blood concentrations of CsA between patients. In this prospective study, seven patients experienced rejection episodes despite therapeutic CsA trough levels. Three of these, plus one not receiving CsA therapy, who happened to be prospectively tested at the time that rejection was clinically diagnosed, had a decrease in induced IL-2 mRNA before treatment was instituted. As a correlation to this observation in patients, induced IL-2 mRNA levels in unmodified rejection were sequentially measured in PBMC cultures in autologous vs allogeneic canine renal transplants and IL-2, IL-10, TNF-alpha, and IFN-gamma mRNA were also measured in kidney biopsies. Sequential PHA lymphoproliferation assays of [3H] thymidine incorporation on patient and dog PBMC cultures were also performed. Similar to the observations in patients, unmodified rejection in the canine renal allograft model also was accompanied by a decline of PHA-induced IL-2 mRNA in PBMCs as the serum creatinine concentrations became elevated. In the dog kidney biopsies at later phases of rejection, IL-10 mRNA levels were also significantly elevated (p = 0.032).

Transplant-associated autoimmune mechanisms in human hepatitis C virus infection

In order to define factors which are important for the development of hepatitis C virus (HCV) infection and disease in transplant patients, we examined the role of class II MHC antigen restriction in viral antigen presentation to support a hypothesis of the association of this disease with an autoimmune pathogenesis. A greater degree of histocompatibility match between these donors and their HCV-negative recipients was associated with a greater predisposition to recipient HCV liver disease (ALT elevation) posttransplant. The HCV carrier state could be identified with significant amplification of autologous mixed lymphocyte reactivity (AMLR) in both long-term hemodialysis and long-term renal transplant patients, but the AMLR was absent in end-stage liver disease patients with HCV-associated cirrhosis and was insignificantly elevated in these patients with persistent infection in the first 2 years after a new liver was transplanted. There was also a moderate reduction in autologous reactivity as well as serum HCV titers among renal transplant patients who displayed biochemical evidence of chronic liver disease as opposed to those who did not. This appeared later in the course of the disease. HCV RNA could be detected in peripheral blood mononuclear cells (PBMC) of only a portion of HCV-infected renal transplant patients and these showed significantly higher autologous reactivity. In contrast, despite the fact that observations were earlier after de novo liver transplantation, HCV RNA (i.e., earlier in the course of a new or recurrent disease process) was found in PBMC of all liver transplant recipients tested. The AMLR of noninfected laboratory volunteers could be amplified by preincubating their stimulating cells (APCs) with enriched HCV possibly in immune complex (pHCV-IC). This amplification appeared only with specific combinations of HCV strains with HLA DR serotypes. In addition, HCV-primed T cells could be generated to the virus which displayed accelerated activation kinetics. Liver infiltrating lymphocytes extracted from HCV-positive end-stage diseased livers had significantly higher proliferative and cytotoxic reactivity to autologous (HCV-infected) hepatocytes than the extracted lymphocytes responding to autologous hepatocytes from HCV-negative livers. These findings offer evidence of dynamic autoimmune mechanisms in the spectrum of progression of HCV disease and may help to predict the effect of intervention at various intervals in this progression in organ transplant recipients.

Cloning and expression of canine interleukin-10

We describe here the cloning of canine IL-10 cDNA (GenBank accession No. U33843) and the expression of recombinant IL-10 in a dog kidney cell line (DK6247) and Chinese hamster ovary cells (CHO). Canine IL-10 exhibits strong sequence homology to the known sequences of human, mouse, rat, and bovine genes at nucleotide and amino acid levels. The IL-10 gene, when introduced into DK and CHO cell lines, produces recombinant IL-10 that causes an inhibitory effect on allogeneic MHC-driven lymphoproliferative responses.

De novo membranoproliferative glomerulonephritis in hepatitis C virus-infected renal allograft recipients

Hepatitis C virus (HCV) is the leading cause of non-A, non-B hepatitis among renal allograft recipients. We sought to identify and describe a proteinuric renal disease occurring in our HCV-infected renal transplant patients. Patients with proteinuria exceeding 1 g/day were identified from a cohort of 98 HCV-infected kidney recipients. Qualitative and quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and restriction fragment-length polymorphism of the amplified RT-PCR product was performed to detect circulating HCV RNA, viral titer, and strain type, respectively. An immune complex nephritis (ICN) of the membranoproliferative pattern (MPGN) was found on five of eight biopsies. Two patients infected with the Hutch strain-type developed nephrotic-range proteinuria within three months posttransplant while the remaining three MPGN patients had been transplanted greater than 5 years prior to the onset of proteinuria. Testing for rheumatoid factors, cryoglobulins, hypocomplementemia, and circulating immune complexes failed to show a consistent pattern. Sucrose density gradient (SDG) equilibrium centrifugation was used to determine the buoyant-density of HCV virions from control (HCV-infected nonproteinuric recipients; n = 5) and nephrotic patients (n = 5). Whereas HCV virions from the control patients had a low buoyant density on sucrose gradients, a substantial percentage of the circulating HCV RNA from the MPGN patients was present in the high-density fractions in association with IgM and IgG. Treatment of the pooled high-density layers with NP40 followed by recentrifugation resulted in a shift of the HCV RNA to the medium-density layers. In conclusion, MPGN developed in five HCV-infected kidney recipients despite pharmacologic immunosuppression. Both the physicochemical properties of the HCV virions on SDG and their association with IgG and IgM in the high-density layers provide indirect evidence for the presence of circulating complexes of anti-HCV antibody and HCV antigen(s).

Transmission of hepatitis C virus by kidney transplantation: impact of perfusion techniques and course of viremia post transplant

Hepatitis C virus (HCV) infection is the leading cause of post-transplant non-A, non-B hepatitis. Although many end-stage renal disease patients present for transplantation already infected with HCV, some recipients acquire the infection by transmission from the donor organ. We have detected serological evidence for HCV infection in 6.8% of our organ donors using second-generation anti-HCV assays. Approximately one-third of the patients who received an organ from a HCV carrier donor developed chronic transaminasemia and 8 of 14 (56%) patients converted from HCV RNA negative to positive in the posttransplant period. Demonstration of the course of viremia and transaminasemia is presented for 2 patients in whom transmission of HCV occurred. Using pulsatile machine perfusion, we were able to demonstrate that a standard perfusion of 20 h reduced the viral load in the kidney by 75%, additional flushes and a subsequent perfusion reduced the total viral titer by more than 99%. Thus, although transmission of HCV does occur with solid-organ transplantation, differences in the incidence of transmission between centers may be related to techniques of organ preservation.

Cloning and expression of the cDNA for canine tumor necrosis factor-alpha in E. coli

We have utilized the reverse transcription polymerase chain reaction (RT-PCR) to clone the protein coding region of canine tumor necrosis factor (TNF-alpha) cDNA. The gene displays 90% sequence homology to the corresponding human TNF-alpha cDNA. The predicted initial translation product is 233 amino acids and shows 88% homology to the human counterpart, and 92% homology with the human putative mature TNF-alpha protein. The canine TNF-alpha clone was used to engineer bacteria to express large amounts of the mature form of recombinant protein. A monoclonal antibody against human TNF-alpha cross-reacted with canine rTNF-alpha using Western blot and ELISA analysis. The purified canine rTNF-alpha had a cytotoxic effect on WEHI 164 clone 13 cells as well as increasing the cell surface expression of major histocompatibility class II antigens on canine kidney cortical cell line (MDCK) in vitro. The availability of canine rTNF-alpha will allow further studies on its role in immunoregulatory mechanisms in the canine transplantation model, both by itself and in conjunction with the already available canine specific recombinant interferon-gamma.

Depletion of hepatitis C virus from procured kidneys using pulsatile perfusion preservation

The safety of the use of kidneys procured from a hepatitis C virus (HCV)-positive cadaver donors in transplantation has recently been the subject of controversy. One factor that is important in determining the transmission of the virus and/or viral liver disease is the total viral inoculum to which the renal allograft recipient is exposed as a result of the transplant. We have studied the effect of a standard pulsatile renal preservation procedure and variations of it on the number of viral copies in organs from HCV-positive donors. An HCV-RNA quantitative reverse transcription-polymerase chain reaction (RT-PCR) method was utilized with a recombinant competitive inhibitor substrate added after cDNA synthesis with the PCR primers within the relatively non-polymorphic 5' untranslated region of the HCV genome. Additionally, strain specificity was found to be detectable using a modification of the technique of restriction fragment-length polymorphism (RFLP-PCR), so that virus from the organ donor could be specifically identified and quantified in the recipient. It was observed that standard preservation procedures using pulsatile perfusion were able to eliminate 75% of the virus from the organ in 20 hr. By modifying this procedure to include additional wash steps and a second pulsatile perfusion, greater than 99% of the virus could be eliminated from the kidney. In a related study, we used quantitative PCR to study requirements for filtration of the virus using HCV-positive serum. It was found that a high-flow-rate ultrafilter with a molecular weight cut-off (MWCO) of 300,000 daltons placed in series to the preservation apparatus was very efficient in eliminating the virus from perfusion solution in less than 2 hr. It can therefore be proposed that with the use of these molecular techniques, pulsatile perfusion coupled with additional viral depletion steps (dilution, and/or filtration) may allow the practical reduction of HCV transmission risk in recipient follow-up studies. The means are thereby presented for similar manipulation of other known or, as yet, unknown transmissible agents.

Characterization of anti-canine cytokine monoclonal antibodies specific for IFN-gamma: effect of anti-IFN-gamma on renal transplant rejection

Two murine monoclonal antibodies specific for IFN-gamma, ADI-1, and ADI-23 (both IgG1 kappa), were generated in BALB/c mice. The ADI-1 exhibited a higher avidity for canine rIFN-gamma than for nIFN-gamma and human rIFN-gamma. In contrast, the ADI-23 showed equal avidity for the three IFN-gamma preparations. The anti-canine IFN-gamma mAb did not bind to mouse and rat rIFN-gamma. The ADI-1, and ADI-23 mAb were also tested for binding to human rTFN-alpha and, contrary to our expectations, it was found that ADI-23 showed significant binding to human rTFN-alpha and rIFN-gamma, in contrast to ADI-1. Both anti-canine IFN-gamma mAb stained 48-h PHA-induced dog lymphoblasts. A two-site mAb ELISA was developed, which was linear in the range of 7-500 ng of canine rIFN-gamma, which indicated that the two mAb detected non-overlapping epitopes on the canine rIFN-gamma molecule. We studied the effect of ADI-1 on the prolongation of canine renal allografts. Recipients of kidney allografts, that were treated with ADI-1 by continuous arterial infusion, were prolonged to 22 and 25 days, compared to 9 and 13 days for animals given the IgG1 isotype control.

The impact of hepatitis C virus infection on renal allograft recipients

A second generation hepatitis C virus recombinant immunoblot assay (RIBA) was used to screen stored perioperative serum from 641 renal allograft recipients. One hundred and nine (17%) were anti-HCV positive at the time of transplant. RIBA positivity was found to be an independent predictor of post-transplant liver disease in a logistic regression model (P < 0.05). Moreover, RIBA positive patients were at greater risk for infectious events (P = 0.03) and rejection episodes (P = 0.002). The cumulative dose of antilymphoblast globulin administered as induction therapy was an independent predictor of post-transplant liver disease in a dose response relationship. Qualitative PCR showed that 74% of the perioperative RIBA positive patients had detectable HCV RNA in a current serum sample. Further, quantitative HCV RNA analysis with a competitive template PCR and HCV strain identification by restriction fragment length polymorphism demonstrated a large range of HCV RNA copies/ml of serum and three different HCV strains (BK, Hutch and HCV-1). Neither quantity of HCV RNA nor strain type correlated with abnormal transaminases post-transplant. As yet, there has not been an effect of anti-HCV status on actuarial patient and graft survival. This study suggests that anti-HCV is not a contraindication to renal transplantation; however, we would recommend that the pre-transplant evaluation of the anti-HCV positive patient include a liver biopsy to properly stage the disease. Close post-transplant follow-up is required in view of the increased risk for infection and rejection.

Differential effects of IFN-gamma on kidney cell expression of MHC class II molecules, kidney cell associated molecules and their stimulatory capacity in mixed lymphocyte kidney cell culture

Mixed cell co-cultures of lymphocytes responding to kidney cells (MLKC), islets of Langerhans (MLIC) and mixed lymphocyte culture (MLC), were used to clarify mechanisms in allogeneic and autoimmune (tissue-associated) antigen presentation. Fresh kidney cortical tubular cells (KC), Madin-Darby canine kidney (MDCK), and dog kidney (6247) (DK) cell lines were used in MLKC reactions, and islets of Langerhans were used in the MLIC as putative antigen presenting cells (APC). The stimulating cells were treated with purified or recombinant dog interferon-gamma (IFN-gamma), and the detection of class II MHC molecule expression was assessed by a moneclonal antibody (mAb) (B1F6). Transcription of MHC class II mRNA and IFN-gamma mRNA was measured by semiquantitative polymerase chain reaction, and detection of a kidney cell (tissue-associated) antigen molecule was assessed by the mAb I1F6 that recognizes 72 and 150 kDa tubular cell protein(s) (KT1). The MDCK cell line constitutively expressed low levels of MHC class II molecules and KT1. The steady-state level of the MHC class II mRNA transcription was virtually unaltered by treatment with IFN-gamma (400 units) for 48 hours; however, the MHC cell surface protein expression was enhanced. The KC and DK cell lines constitutively expressed KT1, but not MHC class II molecules; these cells required a minimum of 4000 units, and a 62-hour incubation with IFN-gamma was needed to upregulate both surface MHC class II molecules and the transcription of corresponding specific mRNA. In the MLKC reaction both the MDCK and DK cell lines, as well as fresh KC cells, could serve as lymphocyte activators. This could be amplified by exogenous IFN-gamma. The removal of APC from the responding T cell population did not reduce the IFN-gamma effect. This indicates that IFN-gamma treatment allows for the expression of all of the co-stimulating factors and/or adhesion molecules necessary for these cells to serve as (surrogate) APC (direct as opposed to indirect antigen presentation). The requirements for purified IFN-gamma to increase this amplification was greater in the MLKC reactions with kidney cells than in the MLC reactions. The mAbs anti-IFN-gamma and I1F6 differed in their ability to inhibit lymphocyte proliferation depending on the different cell types involved. The I1F6 inhibited the MDCK and DK cell-driven MLKC (in the absence of exogenous IFN-gamma).(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular monitoring of the immunosuppressive effects of cyclosporine in renal transplant patients by using a quantitative polymerase chain reaction

We have developed a rapid (24 hours) quantitative PCR assay to measure the direct effect of cyclosporine on IL-2 mRNA production by activated PBMC cultures from renal transplant patients. The PBMCs were purified from normal laboratory volunteers (group A, n = 26), CsA-treated renal transplant patients with good renal function, tested between 3 and 8 weeks (group B, n = 14) or between 2 and 8 years (group C, n = 15) after surgery, and stimulated with PHA in media supplemented with either patient serum or pooled commercially obtained AB serum. The mRNA was then isolated and, using semiquantitative PCR or quantitative PCR with a competitive inhibitor, the relative levels or exact levels of IL-2 mRNA (in attomoles) could be measured. A 3-day confirmatory lymphoproliferation assay of [3H]thymidine incorporation was also performed on the samples. Kinetic analysis of the data from group A showed that the peak level of IL-2 transcription into mRNA occurred at 6 hours after mitogen stimulation. Increasing in vitro concentrations of CsA in this group resulted in lower IL-2 mRNA levels and a shift in the peak time to 12-24 hours. In the transplant recipients, there was no correlation between individual CsA blood levels and proliferation responses. However, some correlation was found between CsA blood levels and IL-2 mRNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Production and characterization of recombinant canine interferon-gamma from Escherichia coli

We have used the recently cloned cDNA for canine interferon-gamma (IFN-gamma) to engineer bacteria to produce large amounts of the recombinant cytokine. The resulting protein can be recognized by monoclonal and polyclonal antibodies largely species specific for canine IFN-gamma. The purified recombinant IFN-gamma (rIFN-gamma) also had biological activity in vitro in three assay systems: (i) vesicular stomatitis virus plaque inhibition, (ii) class II major histocompatibility complex antigen upregulation on canine kidney parenchymal cells, and (iii) amplification of in vitro tissue-associated lymphoproliferation, all known to be effected by native IFN-gamma (nIFN-gamma). The availability of large amounts of active canine rIFN-gamma will be an important tool in studies of the role of this cytokine in the widely used experimental canine organ transplant model and also will be of diagnostic and therapeutic veterinary interest.

Cloning of the cDNA for canine interferon-gamma

We have taken advantage of conserved regions of cDNA sequences for interferon-gamma (IFN-gamma) from other species to design polymerase chain reaction (PCR) primers capable of amplifying the protein-coding region of the canine mRNA. We report here the cDNA cloning of this region from dog lymphocytes and the cDNA sequence. The predicted amino acid sequence is also reported and compared to the known sequences of these other species. The molecular clone for the canine IFN-gamma will allow direct study of this important cytokine's role in graft rejection in the widely used experimental canine transplant model.