University of Miami Team Confirms Value of Monitoring Cell-Mediated Immunity Pre- and Post-Transplant in Management of Kidney Transplant Recipients
MIAMI, June 02, 2008 /PRNewswire/ -- Manuel R. Carreno, MD, and colleagues in the Departments of Surgery and Pathology at the - Lawrence Miller School of Medicine have corroborated the value of monitoring cell- mediated immunity (CMI) post transplant in recipients of kidney transplants using a regular laboratory assay of cell function (ImmuKnow(R)/Cylex). Their paper, entitled "Immune monitoring with Cylex ImmuKnow(R) in the management of post kidney transplant recipients," will be presented on June 2 at the annual meeting of the American Transplant Congress in Toronto, Canada.
"The production of cyclic adenosine monophosphate (cAMP) by mitogen-stimulated peripheral CD4+ T-cells using the ImmuKnow assay has previously be shown to have utility in the management of several forms of organ transplantation," stated Dr. Carreno, "In this study, we wanted to learn whether the ImmuKnow test data correlated with data from other tests and clinical findings in patients undergoing kidney transplantation." Dr Carreno is the Assistant Director of Flow Cytometry and Cell Analysis in the Transplant Laboratories.
Patients undergoing kidney transplantation were immunosuppressed post-transplant and their immunosuppressed state was maintained with a combination of tacrolimus (Prograf(R)) and low-dose steroids. A total of 2,096 specimens were drawn from 339 transplant patients, and additional samples were provided by normal controls. Levels of CMI, as measured in terms of levels of ATP, were measured using the ImmuKnow assay and categorized according to the tests labeling: "low" (<225 ng ATP/mL), "moderate" (225-525 ng ATP /mL) and "strong" (>525 ng ATP /mL).
Several patterns of ATP level over time were noted in the patients and in the normal controls, as follows:
-- The mean level of CMI for blood samples from normal controls (n = 20) was 432 +/- 150 ng ATP/mL (generally well within the "moderate" range). -- Blood samples from patients prior to kidney transplant (n = 91) had a mean CMI level of 342.1 +/- 155 ng ATP/mL, which was lower than that of the normal controls but significantly higher (p < 0.005) than the levels post transplant (see below). -- Blood samples taken from patients within four time periods post transplant had the following mean CMI levels -- 1 to 30 days (Month 1): mean CMI = 203.7 +/- 171 ng ATP/mL -- 31 to 365 days (Months 2 to 12) mean CMI = 249.1 +/- 162 ng ATP/mL -- 366 to 730 days (Year 2) mean CMI = 278.3 +/- 147 ng ATP/mL -- 731 to 1,090 days (Year 3) mean CMI = 263.5 +/- 136 ng ATP/mL
Patients whose pre-transplant CMI level tested in the "strong" ImmuKnow range (n = 10), and whose CMI level remained in the "strong" range post-transplant, showed no evidence of organ rejection. Several patients showed evidence of cellular (n = 8) or humoral (n = 2) rejection while under monitoring. The patients demonstrating cellular rejection all had increases in CMI > 200 ng ATP/mL, with rapid returns toward the mean post-transplant CMI level after good immune function was restored. The two patients demonstrating humoral rejections showed no changes in CMI. Finally, of the 23 patients who contracted infections, 21 (91 percent) demonstrated a drop in CMI level of > 150 ng ATP/mL.
"We believe that serial monitoring of blood samples from kidney transplant patients pre- and post-transplant is now an important aid in the clinical management of these patients," said Phillip Ruiz. MD, PhD, professor of surgery and pathology and head of the Division of Immunopathology. "CMI levels vary significantly, even among stable transplant patients. However, by establishing pre-surgical and post-surgical baseline levels, and monitoring the patients on a regular basis over time, we are able to watch for sudden, significant changes in the patients' CMI levels, which are predictive of either infection or onset of cellular transplant rejection."
The clinical research team further noted that among 29 patients with persistently low CMI levels (< 100 ng ATP/mL) they observed none of the major consequences reported by other investigators and that low absolute CD4+ T-cell levels did not impede the potential for "strong" ImmuKnow response levels.
ImmuKnow is an immune cell function assay that can detect cell-mediated immunity (CMI) in adult patient populations undergoing immunosuppressive therapy for organ transplantation by measuring the concentration of adenosine triphosphate (ATP) released from CD4 cells following cell stimulation.
The ImmuKnow test is a qualitative assay and does not directly quantify the level of immunosuppression. Results of ImmuKnow assays should be used in conjunction with clinical presentation, medical history, and other clinical indicators when assessing the immune status of any individual patient. The use of the ImmuKnow assay as described in this study has not been approved or cleared by the FDA. The company may use data from this or similar studies to support a future FDA marketing application for a similar indication.
About Cylex, Incorporated
Cylex(TM) is a privately held global life sciences company and a leader in the development and manufacture of research and in vitro diagnostic products intended to assist in the assessment of immune function. Cylex is the first and only company to offer a patent-protected in vitro diagnostic assay (ImmuKnow) used in the detection of cell-mediated immune function in immune-suppressed organ transplant patient populations. The ImmuKnow assay is increasingly being adopted for use by organ transplant centers throughout the USA and in other countries around the world. The Company's patented technology provides an innovative platform allowing clinical researchers to simply and reproducibly measure immune cell function for the development of new diagnostics, biomarkers, and companion assays. The company is based in Columbia, MD.
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Posted: June 2008