How are exotoxins produced and how can they be transported round the body?
Exotoxins are usually secreted by bacteria and act at a site removed from bacterial growth. However, in some cases, exotoxins are only released by lysis of the bacterial cell. Exotoxins are usually proteins, minimally polypeptides, that act enzymatically or through direct action with host cells and stimulate a variety of host responses. Most exotoxins act at tissue sites remote from the original point of bacterial invasion or growth. However, some bacterial exotoxins act at the site of pathogen colonization and may play a role in invasion. b) They may be transported both by blood and lymph, Because some exotoxins are so small only polypeptides with a mw about 60 000 daltons they can easily pass through cell walls and so be transported by cells in blood and lymph, sometimes by the agents that are fighting the infection.
