Quote Originally Posted by Gilrandir View Post
Immune system is a misname. The notion of system presupposes elements and relations between them. Unlike digestive system or blood circulatory system or musculoskeletal system the "immune system" doesn't have organs connected with each other to perform the protecting function. It is rather lymphatic system plus a bunch of miscellaneous organs of other systems (including the skin) that address the task of protecting the body against infections. In no way do they form a system.
There is a system and also coordination going on in the immune system. If not so much between organs, there is certainly coordination between cells: http://kidshealth.org/en/parents/immune.html

Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it without help. That's the job of the T cells, which are part of the system that destroys antigens that have been tagged by antibodies or cells that have been infected or somehow changed. (Some T cells are actually called "killer cells.") T cells also are involved in helping signal other cells (like phagocytes) to do their jobs.
IIRC the problem with AIDS is that it attacks the type of cell that would alert others to destroy the invading AIDS, thus blunting the reaction of the immune system and making the body more susceptible to other attacks as well since AIDS has knocked out an important part of the defense system. This wouldn't be as problematic if the rest of the system worked without getting triggered by the cells that AIDS knocks out.
Then again my biology class on this stuff was >10 years in the past...