The immune system is a system of many biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.o function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.
The cost to run for president in the general election can amount to at least $70 million USD, although the amount of money required can vary. It is possible that at some point in the future, all presidential candidates will run without taking any federal contributions.
Despite such concerns, campaign costs are unlikely to fall. A super-PAC supporting the as-yet-unannounced candidacy of Hillary Clinton in a presidential election still more than two years off has already raised more than $4m.