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In 1882, Élie Metchnikoff pushed a rose thorn into a starfish larva and watched cells swarm to engulf it. That observation, cells eating foreign objects, became a foundation of innate immunity and helped earn him the Nobel Prize in 1908.

For over a century, phagocytosis was textbook immunology. Important, foundational, and extensively studied. Then immuno-oncology changed the stakes. Tumor cells protect themselves by displaying "don't eat me" signals, most famously CD47. A new generation of therapeutics, including anti-CD47, anti-SIRPα, and anti-CD24 approaches, aims to block those signals and re-enable macrophages to engulf cancer cells. Suddenly, one of the oldest immune mechanisms in the book became one of the hottest readouts in drug discovery.

The assay is conceptually simple: mix phagocytes with fluorescently labeled prey, image them, and quantify the interaction. But the analysis is deceptively hard. Phagocytosis demands counting discrete objects within other objects: prey particles associated with phagocytes. A macrophage associated with eight bacteria is biologically very different from one associated with one, but a plate reader may report both as simply "positive." Bulk fluorescence collapses that distribution into a single number and hides the biology.

Cytely segments phagocytes, detects prey particles as sub-objects within each cell, and reports a prey count per phagocyte. Not a binary positive/negative readout, but the actual single-cell distribution. In assays where internalization status matters, pH-sensitive dyes such as pHrodo can also help distinguish surface-bound from truly internalized prey. The platform also computes the image multiplicity of prey, or iMOP, to normalize across wells where prey density varied.

How the assay runs

Segment phagocytes → detect prey particles → measure prey count, area, and intensity per phagocyte. Internalization can be scored using a pH-sensitive dye (e.g., pHrodo, which fluoresces only when internalized) or by estimating 3D overlap. iMOP provides a control metric for normalizing phagocytic activity against prey availability.

What you provide

  • Ch1: DAPI
  • Ch2: phagocyte marker or cell mask
  • Ch3: labeled prey (e.g., pHrodo-labeled bacteria, fluorescent beads, synaptosomes)

What you get

  • Prey count per phagocyte
  • Total prey area per cell
  • % phagocytosis-positive cells
  • Prey intensity per cell
  • Internalization scoring (surface-bound vs internalized prey via marker or 3D estimate)
  • Image multiplicity of prey (iMOP — estimated prey-to-cell ratio in the sample)

Ready to run

Macrophage, microglial, neutrophil, or monocyte/THP-1 phagocytosis. Bead-based, bacterial, synaptosome engulfment, efferocytosis (clearance of labeled apoptotic cells), antibody-dependent cellular phagocytosis (ADCP), any labeled-prey assay. Internalization scoring via pH-sensitive dyes or 3D estimation.

Inquire for support

Live-cell phagocytosis kinetics, phagosome maturation tracking.

Explore the Phagocytosis assay →