1.1.2　The Complement System

The complement provides innate immunity.It is comprised of a collection of proteins that“recognise” corresponding proteins on the cell walls of invading microbes.When such invading microbes have been recognised, the following actions are taken.

· The “alarm” is sounded.Chemicals, known as chemotaxins, that attract phagocytes are emitted.This process is known as chemotaxis.The phagocytes follow the trail of chemotaxins to arrive at the site of invasion.(https://www.daowen.com)

· The invading bacteria are “marked” with chemicals that make them stand out.These chemicals are known as opsonins, from the Latin word opsonium, meaning “sauce”.This “marking” greatly increases the chances of the invading bacteria being phagocytosed.

· Chemicals are released which promote the inflammatory r esponse.More on the inflammatory response later.