In April 2002, the FDA approved the Cylex Immune Cell Function Assay (Cylex Inc., Columbia, MD) for the detection of cell mediated immune response in populations undergoing immunosuppressive therapy for organ transplant. The test measures ATP concentrations and purports to be able to predict how well a transplant would “take”. A variety of studies since 2009 have reached conflicting and contradictory conclusions regarding the utility of this test in liver, heart and kidney transplantation. Some showed no efficacy and others had promising but inconclusive results and recommend farther study. The American Society of Transplantation (AST) does not currently mention the use of the Cylex Immune Cell Function assay in its recommendations for the screening, monitoring and reporting of infections complications in the evaluation of recipients of organ transplantation (AST, 2006). Chon and Brennan (2009) commented that there is no consensus on the utility of the Immuknow assay in renal transplant rejection other than in the research setting. Martinu et al (2009) commented that “the data in lung transplantation are scarce and not very promising to date”, and that “the ImmuKnow assay does not seem to have the potential to differentiate between infection and rejection in lung transplant recipients and, until more data becomes available, should not be used clinically in this patient population.”
More recent studies continue to exhibit the same pattern. Torio et al (2011) stated that the Cylex ImmuKnow assay provides a rapid assessment of global immune function in immunocompromised patients by measuring the global immune responses of CD4 T cells from a whole-blood sample. The authors concluded that these findings confirmed that the ImmuKnow assay identified transplant patients at risk for infection. It may provide information to guide immunosuppressive therapy, but the assay did not seem to have the potential to differentiate subjects experiencing rejection.
De Paolis et al (2011) concluded that this preliminary analysis showed a beneficial capacity of this assay to represent the global depression of the immune system.
Huskey et al (2011) concluded that studies 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. A number of other studies reached similar conclusions.
This test is not currently recommended by any guidelines and should be considered investigational at this time.
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