phagocytosis: a standalone construct

Élie Metchnikoff, who in 1882 watched motile cells surround and engulf a splinter he had pushed into transparent starfish larvae, coined the term for the process and built from it the phagocyte theory he set out in his 1892 book Leçons sur la pathologie comparée de l'inflammation, work later recognised with a share of the 1908 Nobel Prize in Physiology or Medicine. Phagocytosis is the process by which a cell engulfs a relatively large target, a microbe, a dead cell, or debris, by extending its membrane around it and enclosing it in an internal sac called a phagosome, which then fuses with digestive compartments that break the contents down. In animals it is carried out chiefly by specialised white blood cells such as macrophages and neutrophils, and it serves both as a first line of defence against infection and as the routine way of clearing dying cells and cellular waste. Modern cell biology has mapped the receptors that recognise a target, the actin-driven reshaping of the membrane that draws it in, and the stepwise maturation of the phagosome (Aderem & Underhill, 1999; Flannagan, Jaumouillé & Grinstein, 2012). What makes phagocytosis a landmark construct is its span: one mechanism links comparative zoology, innate immunity, and everyday tissue housekeeping, and it names the specific act of a cell taking in a discrete particle, distinct from the bulk uptake of fluid.[1][2][3]

Unit

A cellular process of particle uptake, one act of engulfing a discrete target into a phagosome

Recovery means

Not applicable

Measured by

Observed by microscopy of engulfed targets and quantified with uptake assays using labelled beads, particles, or microbes together with markers of phagosome maturation