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Research in transplant medicine provides new insights
(Science Letter Via Thomson Dialog NewsEdge)
Reports from the People's Republic of China, United States and Netherlands highlight recent research on transplant medicine.
Study 1: Acute rejection may occur during bacterial pneumonia treatment after liver transplantation.
"Bacterial pneumonia in the recipients of liver transplantation (LTX) is a common postoperative complication influencing the prognosis greatly. In this article, the diagnosis and treatment of bacterial pneumonia in 33 LTX recipients are reported," researchers in People's Republic of China wrote.
"From February 1999 to January 2003, a total of 103 patients underwent allogeneic LTX at our center; afterwards, a retrospective analysis was made on their postoperative clinical manifestations, including symptoms (expectoration, panting and fever), sign (rale), results of laboratory examinations (white blood cell count and sputum culture of tracheal secretions or pleural fluid culture), and chest X-ray films."
"The following data of the pneumonia and non-pneumonia groups were collected, and the rank sum test (SPSS 11.0, Wilcoxon's method) was used to analyze the duration of postoperative respirator utilization and the volume of pleural effusion through pleurocentesis or pleural drainage," reported the investigators.
According to Y.K. Ma and colleagues at Sichuan University in Chengdu, "In the 103 patients, 33 experienced 53 episodes of bacterial pneumonia during their hospital stay after transplantation, 14 of them (42.42%) had more than three manifestations of the seven mentioned above. The pathogens causing bacterial pneumonia included Pseudomonas aeruginosa (17.48%), Klebsiella pneumoniae (15.53%), Acinetobacter baumannii (10.68%), and Staphylococcus aureus (7.77%). Amilkacin, tienam, ciprofloxacin, vancomycin, etc. were the antibiotics of choice against those bacteria."
"Acute rejection occurred during the treatment of bacterial pneumonia in 16 patients, and 5 of them died. Wilcoxon's rank sum test of the data indicated that the pneumonia group had longer duration of postoperative ventilator treatment and larger volume of pleural effusion than the non-pneumonia group (p<0.05)," reported the authors.
They concluded, "The clinical manifestations of pneumonia after LTX might be atypical, and special attention should be paid to the respiratory symptoms and signs within 2 months after LTX. Whenever the diagnosis of bacterial pneumonia is confirmed, consideration should be given to reasonable use of antibiotics and regulation of immunity in addition to other routine therapies."
Ma and colleagues published their study in Chinese Medical Journal (Diagnosis and treatment of bacterial pneumonia in liver transplantation recipients: report of 33 cases. Chin Med J (Engl), 2005;118(22):1879-1885).
For additional information, contact Y.K. Ma, Sichuan University, W. China Hospital, Dept. General Surgery, Liver Transplantation Center, Chengdu 610041, People's Republic of China.
Study 2: According to recently published research from the United States, ribavirin concentrations do not predict hepatitis C virus (HCV) RNA clearance or the need for erythropoitin factor.
"HCV infection is the most common indication for liver transplantation (LTx) in the United States. Ribavirin with pegylated interferon is the only treatment option for HCV recurrence in post-LTx patients," wrote A. Jain and colleagues, University of Rochester.
"In clinical practice, for more than 50% of patients, ribavirin dose needs to be modified. The aim of this study was to examine the role of ribavirin level and its relevance in the management of post-LTx patients in terms of renal dysfunction, efficacy, toxicity, and potential drug interactions."
The investigators explained, "Thirty-four blood samples were available from 22 post-LTx patients. Ribavirin concentrations in plasma (all samples) and whole blood concentrations (16 samples) were examined. The dose of ribavirin ranged from 400 mg/d to 1000 mg/d, but concentrations were normalized to 800 mg/d."
"There was a wide variation in plasma concentration of ribavirin, ranging from 1.8 to 122.1 mg/mL. The concentrations were similar in whole blood and plasma. Dose-normalized concentration with creatinine clearance below 70 mL/min were significantly higher when compared with creatinine clearance above 70 mL/min (p=.015)."
"Eleven patients required erythropoietin; their mean ribavirin dosage was higher but mean ribavirin concentration was lower compared to the 11 patients who did not require erythropoietin factor. There was no difference in mean ribavirin concentration in patients who cleared the virus (n=7) compared and who did not clear the virus (n=9)," reported the authors.
"Three patients were on nucleoside reverse transcriptase inhibitors (NRTI) had significantly higher concentration (mean 87.1 mcg/mL) compared to those who did not receive NRTI (mean 34.4 mcg/mL, p=.00)."
Jain and coinvestigators wrote, "Ribavirin concentration in plasma and whole blood were similar, with a wide variation. Patients with impaired renal function and those who were on NRTI had significantly higher concentrations of ribavirin."
"The ribavirin concentrations did not predict either the clearance of HCV RNA or the need for erythropoitin factor," concluded the researchers.
Jain and colleagues published their study in Transplantation Proceedings (Ribavirin levels in post liver transplant patients treated for recurrent hepatitis C viral infection. Transplant Proc, 2005;37(7):3190-3196).
For more information, contact A. Jain, Strong Memorial Hospital, Department of Surgery, Transplant Division, University of Rochester, Rochester, NY 14642, USA.
Study 3: Hepatitis B immunoglobulins avert acute rejection after liver transplantation.
"The efficacy of antiviral intravenous immunogobulins (anti-HBs Ig and anti-CMV Ig) in preventing acute rejection after liver transplantation was assessed in a retrospective analysis, and correlated to their effects on immune cells in vitro," scientists in the Netherlands report.
"HBs Ag-positive liver graft recipients (n=40) treated prophylactically with anti-HBs Ig had a significantly lower incidence of acute rejection compared with recipients without viral hepatitis (n=147) (12% vs. 34%; p=.012), while the incidence of rejection in HCV-positive recipients (n=29) was similar to that in the control group," J. Kwekkeboom and colleagues, Erasmus MC wrote.
They continued, "Treatment with anti-CMV Ig (n=18) did not protect against rejection. In vitro, anti-HBs Ig suppressed functional maturation of and cytokine production by human blood-derived dendritic cells (DC) at concentrations similar to the serum concentrations reached during anti-HBs Ig treatment of liver graft recipients."
"In addition, anti-HBs Ig inhibited allo-antigen- and lectin-stimulated proliferation of peripheral T cells. Anti-CMV Ig suppressed functional DC-maturation and alloantigen-stimulated T-cell proliferation, but not lectin-driven T-cell proliferation."
"Anti-HBs Ig protects against acute rejection after liver transplantation, probably by functional inhibition of the two principal immune cells involved in allograft rejection, DC and T cells," researchers concluded.
Kwekkeboom and colleagues published their study in American Journal of Transplantation (Hepatitis B immunoglobulins inhibit dendritic cells and T cells and protect against acute rejection after liver transplantation. Am J Transplant, 2005;5(10):2393-2402).
For additional information, contact J. Kwekkeboom, Erasmus MC, University of Medical Center, Dept. Gastroenterology & Hepatology, Rotterdam, Netherlands.
Keywords: Rotterdam, Netherlands, Allograft Rejection, Hepatitis B Virus, Hepatology, Liver Failure, Immunoglobulins, Immunology, Liver Transplantation, Transplant Medicine, Antiviral Therapy, Liver Allograft, Virology.
This article was prepared by Science Letter editors from staff and other reports. Copyright 2006, Science Letter via NewsRx.com.
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