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

Abstract

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.