Assessment of the Cylex ImmuKnow Cell Function Assay in Pediatric Heart Transplant Patients

Background The Cylex ImmuKnow (Cylex, Columbia, MD) cell function assay (CICFA) is a commercially available test of immune response that purportedly identifies solid organ transplant patients at risk for either acute rejection (AR) or infection. Data on the utility of this test in pediatric heart transplant patients are very limited. This study tested the hypothesis that CICFA is a clinically useful test in this transplant population. Methods All children undergoing heart transplantation at the study center (1989–2006) for whom CICFA levels were obtained were reviewed. The association of CICFA levels with episodes of AR and significant infections was determined. Results Among 83 patients (34 girls, 41%), 367 CICFA levels were obtained (median, 4.0; interquartile range [IQR], 2.0–6.0 per patient). There were 26 episodes of AR in 17 patients (20%) and 38 infections in 34 patients (41%). CICFA levels were similar among patients with AR at the time of the CICFA measurement (median, 325 [IQR, 163–480] adenosine triphosphate [ATP] ng/ml) vs patients without AR (median, 330 [IQR, 227–441] ATP ng/ml; p = 0.36). CICFA levels were similar among patients with infections within 1 month of CICFA measurement (median, 295 [IQR, 216–366] ATP ng/ml) and those without infections (median, 330 [IQR, 226–453] ATP ng/ml; p = 0.24). Conclusions The CICFA is not predictive of AR or significant infections in pediatric heart transplant patients. On the basis of the available evidence, this assay cannot be recommended as part of the routine management of pediatric heart transplant patients.