The Phagocytic process can be divided up into a number of clearly defined stages broadly defined as attachment or particle binding, ingestion and destruction. Unless phagocytes are able to bind to the microbe, phagocytosis will not take place. By utilizing both opsonized and non-opsonized organisms, both opsonic capacity and phagocytosis can be measured at the same time. Thus it is important to determine whether abnormal phagocytosis is due to a failure in the opsonization process or a defect in the ingestion capability of the phagocyte. Since the main cell receptors for phagocytosis are C3b (CR1) and FcR (Fc portion of IgG) it is also possible to evaluate these functional receptors as discussed earlier.
Phagocytosis of bacteria has been extensively developed for flow cytometry primarily by Bassoe et al. Immune complexes can also be measured in methods similar to those for bacteria. Flow cytometry may have an advantage over other methods because of the relatively small number of cells required and less preparative procedures for isolating leukocytes.
