About the Whole Blood Cell Binding Assay

Off-target binding of a therapeutic molecule to cellular components of whole blood can be a safety concern in the clinic. For example, drug interactions with platelets can cause platelet activation and destruction, thereby increasing the risk for thrombocytopenia, a low platelet count. Off-target binding of a therapeutic to cellular components in the blood may also affect biodistribution and bioavailability of that therapeutic, ultimately impacting its pharmacokinetic properties. The whole blood cell binding assay provides an in vitro screen to determine the binding potential of a therapeutic to cell types of interest (off-target or on-target) using flow cytometric analysis.

At iQ Biosciences, we have experience performing cell binding assays with all cellular components of whole blood. In this assay, fresh whole blood is obtained from healthy donors and processed into multiple components: red blood cells (RBCs), platelet rich plasma (PRP), and/or peripheral blood mononuclear cells (PBMCs; T cells, B cells, monocytes, and natural killer cells). Cells are incubated with the therapeutic candidate, followed by and appropriate fluorescently-labeled secondary antibody, if applicable, in order to detect test article binding to each target cell type. Cells are co-stained with appropriate lineage markers, as applicable, to identify potential therapeutic binding to cell subsets of interest within PBMCs. This assay is typically performed with a range of therapeutic concentrations and with more than one healthy donor to elucidate any dose-responsive or donor-dependent effects.