Monitoring Immune Function by the Cylex Immuknow Assay in Pediatric HSCT Patients.

A observational analysis of immune function in six pediatric HSCT patients (3 allogeneic/3 autologous) ranging in age from 3 to 16 years (median = 8.6) was conducted at Children’s Hospital; Louisiana State University Health Sciences Center using ImmuKnow®, an FDA cleared assay for assessing T cell activation. This whole blood assay measures the immune function of CD4+ T-helper cells by stimulating cells with phytohemagglutinin (PHA), selecting CD4+ cells with antibody coated magnetic particles and detecting ATP by bioluminescence, an indicator of activation. The immunknow assay was obtained weekly post-HSCT. On average, the ImmuKnow value for the allogeneic patients was 109 ng/mL ATP with a median value of 63 ng/mL ATP. In two of the three allopatients, a rapid and significant rise in immuknow levels correlated with clinical complications. One ALL patient, given an allogeneic PBSCT from a HLA-ID sibling, developed Veno-occlusive disease (VOD) of the liver, 18 days post BMT with a corresponding spike in the ImmuKnow level to 500 ng/mL ATP. Following treatment with defibrotide, the VOD resolved and ImmuKnow ATP levels decreased, stabilizing between 100–150 ng/mL ATP. A second allopatient showed dramatic rise in immuknow level at day 18 post transplant to 480ng/mL ATP that corresponded with gross hematuria secondary to urethritis. In autologous BMT patients, the average ImmuKnow value was 133 ng/mL ATP with a median value of 70 ng/mL ATP. Clinical correlations were less clear in this small sample of patients with fewer test values. ImmuKnow has previously been demonstrated to have clinical utility for managing immunosuppressive therapies in solid-organ transplantation (SOT)¹ The range of immune function values in pediatric patients has previously been shown to be significantly lower than adult ranges.² Our data suggest that this assay may also be useful as a marker for the development of complications post-HSCT. Additional studies are in progress to confirm these early findings that suggest that routine immune function monitoring is of clinical value in the allogeneic HSCT recipients.