Abstract 7631: Protein Plus BCT: A novel blood collection tube for stabilizing plasma proteins of interest in ambient whole blood storage

Abstract

Abstract Introduction: Many of the soluble plasma proteins (e.g., cytokines) that are crucial for cancer diagnosis, prognosis, and prediction of cancer immunotherapy outcomes are found in blood cells such as platelets and leukocytes. During blood collection and sample storage, ex vivo platelet activation, hemolysis, and blood cell degradation can occur, which causes the release of blood cell-secreted proteins into the plasma. The contamination of these proteins may confound true in vivo levels of plasma proteins of interest, resulting in inaccurate or inconsistent assay results. Protein Plus BCT is a new blood collection tube that maintains accurate plasma protein levels during ambient whole blood storage. Methods: Blood samples from self-proclaimed healthy donors were drawn into Protein Plus BCT, EDTA, and ACD-A tubes. All the samples were stored at ambient temperature for up to 5 days. Plasma was isolated using a general double-spin protocol and frozen at -80 °C until use. Plasma levels of protein biomarkers were measured by Ella Simple Plex Assays (Bio-Techne) and Luminex xMAP® Technology Assays (Bio-Techne, samples tested by LuminexPLORE Lab) following manufacturers’ dilution and processing recommendations. Results: Over 50 key plasma proteins like cytokines, cancer, and immuno-oncology checkpoint markers in samples collected into Protein Plus BCT were analyzed by immunoassays and compared side-by-side to those collected in EDTA and ACD-A tubes. EDTA and ACD-A samples exhibited a substantial elevation in the plasma concentration of many, such as IL-8, IL-1β, HGF, VEGF, MMP-9, CCL5/RANTES and TGF-β1 post draw, indicating platelet activation and blood cell degradation during ambient temperature storage. Samples collected into Protein Plus BCT displayed limited ex vivo platelet activation and minimal contamination by blood cell-secreted proteins, maintaining the draw-time plasma levels of proteins of interest for up to 5 days in whole blood at ambient temperature. Conclusions: The novel Protein Plus BCT maintains draw-time plasma protein levels during extended whole blood storage at room temperature by limiting ex vivo platelet activation, hemolysis, and blood cell degradation. Protein Plus BCT ensures sample integrity and minimizes preanalytical variables, providing cancer researchers and clinical assay developers greater flexibility in sample handling and improved confidence in downstream plasma protein analysis. Protein Plus BCT is for Research Use Only. Not for use in diagnostic procedures. Citation Format: Jing Li, Nicholas M. George, Sama Mehta, Jordan LaRue, Eunju Seong, Nursen Binbuga, Rachel Miller, Karl Bisselou. Protein Plus BCT: A novel blood collection tube for stabilizing plasma proteins of interest in ambient whole blood storage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7631.