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Updated: Jun 6, 2026
Enzyme-linked Immunospot Assay (ELISPOT): Quantification of Th-1 Cellular Immune Responses Against Microbial Antigens
Published on: November 23, 2010
Single time point immune function assay (ImmuKnow) testing does not aid in the prediction of future opportunistic
Janna Huskey1, Jane Gralla, Alexander C Wiseman
1Transplant Center, Department of Pediatrics, University of Colorado, Denver, CO, USA.
Insights
The ImmuKnow assay did not predict opportunistic infections or acute rejection in kidney transplant recipients. Further research is needed to determine the optimal use of this immunosuppression monitoring tool.
Area of Science:
- Immunology
- Transplantation Medicine
- Clinical Diagnostics
Background:
- Current methods for assessing immunosuppression in renal transplant recipients are suboptimal.
- The ImmuKnow assay measures intracellular CD4+ T cell ATP release to quantify cell-mediated immunity.
- This assay is a potential tool for identifying patients at risk of opportunistic infections (OI) or acute rejection (AR).
Purpose of the Study:
- To evaluate the predictive value of the ImmuKnow assay for subsequent opportunistic infections (OI) and acute rejection (AR) in renal transplant recipients.
- To determine if single time point ImmuKnow assay values can identify patients at risk for adverse events within 90 days post-transplantation.
Main Methods:
- Retrospective analysis of 1330 ImmuKnow assay values from 583 renal transplant recipients.
- Correlation of assay values with subsequent episodes of OI and AR within 90 days.
- Comparison of assay values with a control population matched for age, gender, and time post-transplantation.
Main Results:
- No significant differences in mean ImmuKnow assay values were found between patients who developed OI (n=94) and matched controls (386 vs. 417 ng/ml, P=0.24).
- Similarly, no differences were detected in assay values for patients who experienced AR (n=47) compared to controls (390 vs. 432 ng/ml, P=0.25).
- "Low" (≤225 ng/ml) and "strong" (≥525 ng/ml) ImmuKnow assay values lacked sensitivity and specificity in predicting subsequent OI and AR, respectively.
Conclusions:
- Single time point ImmuKnow assay values were not associated with the subsequent development of OI or AR within 90 days in renal transplant recipients.
- The findings suggest that the ImmuKnow assay, as currently utilized, may not be an effective tool for predicting adverse events in this patient population.
- The optimal application and interpretation of the ImmuKnow assay in kidney transplantation require further investigation.
Background And Objectives:
Current assays and tests that are used to determine the degree of immunosuppression in renal transplant recipients are suboptimal. The ImmuKnow assay (Cylex), a measure of intracellular CD4+ T cell ATP release proposed as a means to quantify cell-mediated immunity in transplant recipients, could be considered as a potential tool to identify patients at risk for opportunistic infections (OI) or acute rejection (AR).
Design, Setting, Participants, & Measurements:
We retrospectively analyzed 1330 ImmuKnow assay values in 583 renal transplant recipients at a single center from 2004 to 2009 and correlated these values with episodes of OI and AR in the subsequent 90 days. Assay values were compared with a control population matched for age, gender, and time post-transplantation.
Results:
In patients with OI (n=94), there were no differences in prior mean assay values compared with matched controls (386 versus 417 ng/ml, P=0.24). In 47 patients with AR, again no differences were detected in prior assay results (390 versus 432 ng/ml, P=0.25) when compared with controls. "Low" values (≤225 ng/ml) lacked sensitivity and specificity as a predictive test for subsequent OI, as did "strong" (≥525 ng/ml) values as a predictive test for subsequent AR.
Conclusions:
Our results fail to show an association between single time point ImmuKnow assay values and the subsequent development of an adverse event in the subsequent 90 days. The optimal use of the ImmuKnow assay in kidney transplantation has yet to be determined.
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