Interpretation of low reactivity in the Abbott Architect rHTLV I/II assay

摘要

SUMMARY Objective The objective of this study is to reduce donor tissue wastage. Aim The aim of this study is to determine, in the case of the Abbott Architect rHTLV I/II assay, whether a signal/cut‐off (S/CO) ratio higher than the manufacturer's recommendation of 1·0 could be applied to diagnose significant HTLV‐1 seroreactivity. Background The detection of human T cell leukaemia virus type 1 (HTLV‐1) infection is primarily based on serology often utilising random access platforms. Although current assays have high sensitivity and specificity, in low‐prevalence regions, significant numbers of false‐positive reactions occur. A comprehensive follow‐up is difficult within the time frame of organ donation. This can lead to donor tissue wastage. Methods A retrospective analysis of 12 250 samples previously tested on the Abbott Architect rHTLV I/II platform and further tested by confirmatory serology/molecular detection to determine the sensitivity and positive predictive value in the S/CO ratio range was conducted. Results Where the sample S/CO ratio was 20 (n = 498), HTLV infection was confirmed in all but eight subjects. All of these eight had indeterminate confirmatory results, and none were found to be uninfected. Conversely, in the samples within the S/CO ratio range 1–4 (n = 271), no subject was subsequently found to be HTLV‐infected although HTLV infection could not be excluded in all cases, primarily due to lack of follow‐up samples (n = 60/271). Conclusions Samples with an S/CO ratio of 4·0 on the Abbott Architect rHTLV I/II platform represent a low risk of HTLV infection in the UK, and organs from such donors might reasonably be considered for transplantation, within the context of appropriate risk–benefit assessment.