Opsonise

Part of speech: verb

Definitions

1. To coat a microbe or other particle with antibodies or complement proteins so that immune cells can more readily engulf it
2. Making a bacterium or foreign cell more easily consumed by white blood cells through binding it with special proteins
3. Preparing an invading organism for destruction by marking its surface with molecules that attract scavenging immune cells

Etymology: "Opsonise" is a 20th-century scientific coinage, not an ancient word. It is built from "opson," a term taken from ancient Greek, where "opsōnion" (or "opson") meant food eaten with bread, such as fish, relish or delicacies. That sense of savoury extras accompanying a staple is the root of the modern meaning. The suffix "-ise" (also spelled "-ize") turns the noun into a verb meaning to act upon something in a particular way. The scientific use arose because immunologists needed a name for a substance in blood serum that prepares invading microbes for ingestion by white blood cells. The image is of a seasoning that makes something palatable: the serum coats bacteria so that phagocytes, the cells that engulf them, can take them in more readily. Calling this process "opsonising" captured that preparing-for-a-meal function, which the Greek root had already suggested.