A phagocytosis assay is a laboratory test designed to assess the function of specialized immune cells known as macrophages. There are a number of types of phagocytosis assay used in the lab, including both commercially available tests and tests custom developed for specific labs or experiments. In this test, a collection of macrophages is made and cultured before being exposed to particulate material to see how many cells engulf particles and how quickly they operate. This test has a number of applications.
Macrophages are an important part of the immune system. They work by engulfing particles of material encountered in the body, acting like a cleaning service to clear out infectious agents, the remainders of infections, and any foreign materials. In a person with a strong immune system, these cells will be highly active. In a weakened immune system, there are fewer macrophages and they are less functional. The phagocytosis assay provides information about how active the cells are in the body.
The cells are introduced to a culture with a foreign material inoculated with something that can be used as a tracer. Commonly, fluorescent tags are attached to the material, allowing people to observe macrophage activity under a microscope in specialized lighting. When phagocytic activity is high and the cells work quickly to engulf material, it is indicative of a strong and aggressive immune system. People can also examine how the cells respond to particular types of materials, as for example when testing the efficacy of vaccines.
A number of things can impact macrophage activity and alter the results of a phagocytosis assay. Medications can boost or undermine immune function, and people also respond to environmental factors like exposure to disease and allergens. Vaccinations can teach the immune system to recognize specific antigens, and in a phagocytosis array, the level of macrophage response can be quantified to study a vaccine. If a vaccine works poorly, the cells will not be very active, indicating that the inoculated patient is not safe from disease.
As with other lab tests, the system used for performing a phagocytosis array is standardized and people are expected to follow a lab manual or the directions on a particular test product. This is intended to make test results repeatable while also carefully controlling quality. Samples have to be handled with care to avoid contamination and all observations made during the phagocytosis assay are noted, as they may provide important information usable in repeats of the test or future studies.