Decentralised CD38 activation monitoring: aspects of practical implementation and standardisation

In light of the HIV pandemic, significant strides have been made in improving treatment options for patients. Technologies to monitor the progress of a patient on such treatment have therefore also been scaled up. Immune activation as measured by CD38 mean fluorescence intensity (MFI) on CD8 T cells has been successfully shown in a clinical trial to predict response to antiretroviral therapy (ART) and reported as a cost effective real time test to supplement more costly VL testing. In this study we report transfer of this technology from the research into the routine environment.

This study was conducted in 2 parts: Firstly, fresh random samples (n=75) were tested at four time intervals (0, 24, 36 and 48 h) post-venesection to review reproducibility of CD38 MFI expression. Secondly, the CD38 MFI assay was introduced into a pilot regional testing facility and random samples (n=40) were validated against values obtained on matched samples tested at the reference laboratory.

The CD38 assay showed acceptable accuracy and reproducibility up to 36 h (98% similarity) after venesection with some reduction in CD38 MFI to 94% at 48 h (bias<0.2MFI, %CV<5). Implementation at the secondary testing site was successful with 98% similarity (% SIM CV<5%) compared to the reference laboratory.

The assay proved stable over time and could be tested until 48 h after venesection with no loss of CD38 MFI. Off-site implementation also proved successful, as such, the CD38 assay offers a reliable real time supplementary test to long-term VL monitoring of HIV infected patients on the national ART programme.