THP-1-CD16A macrophages with phagocytosed IgG-opsonized human platelets.

Three different images are shown of IgG-opsonized platelets incubated with THP-1-CD16A macrophages. Platelets were labelled with 5- chloromethylfluorescein diacetate (CMFDA) (green) before phagocytosis. Non-phagocytosed platelets were differentiated after phagocytosis using an AF647-conjugated anti-human CD42a antibody (red). Platelets were additionally defined by size (roughly 1.5 to 3.5 μm) to distinguish them from internalized microparticles or platelet aggregates. THP-1-CD16A macrophages were observed by spinning-disc confocal microscopy under 63x objective oil immersion with differential interference contrast and DAPI stain on a Quorum multi-modal imaging system (Quorum Technologies, Ontario, Canada). Four images were taken at the center of each well with Z-stacking. Phagocytosis was quantified using Imaris v9.6.0. Scale bar = 3 μm. White arrows indicate examples of phagocytosed platelets.