Multiplexed micronutrient, inflammation, and malarial antigenemia assessment using a plasma fractionation device

Collecting, processing, and storing blood samples for future analysis of biomarkers can be challenging when performed in resource limited environments. The preparation of dried blood spots (DBS) from heel or finger stick collection of whole blood is a widely used and established method. DBS pose less risk of infection from blood borne pathogens, do not require immediate specimen processing and tolerate a wider range of storage temperatures, and are easier to ship. As such, DBS are commonly used in large-scale surveys to assess infectious disease status and/or micronutrient status in vulnerable populations. Recently, we reported that DBS can be used with a multiplexed immunoassay, the Q-plex™ Human Micronutrient 7-plex Array (MN 7-plex). This tool can simultaneously quantify seven protein biomarkers related to micronutrient deficiencies (iodine, iron and vitamin A), inflammation and malarial antigenemia using plasma or serum. Serum ferritin, a key iron biomarker, cannot be measured from DBS due to red blood cell (RBC) ferritin confounding the results. In this study, we demonstrate the performance of a simple and rapid blood fractionation tool that passively separates serum from cellular components via diffusion through a membrane into a plasma collection disc (PCD) to produce plasma spots. We evaluated the concordance of MN 7-plex analyte concentrations from matched panels of eighty-eight samples of PCD, DBS, and wet plasma prepared from anticoagulated venous whole blood. The results show high correlation between eluates from PCD and DBS and wet plasma for each analyte. Serum ferritin measures from the PCD eluates were highly correlated to wet plasma samples. This suggests that surveillance for iron deficiency may be improved over the current methods restricted to only measuring sTfR in DBS as when used in combination with the MN 7-plex, all seven biomarkers can be simultaneously measured using PCDs.