Zurr

Thanks for the answer. From what I've read, would it be correct to assume that, generally, if there is an organism that does not know what a human is, it would not have evolved any specific mechanism for escaping phagocytosis? If that is the case, then the human immune system is able to identify 'intruders' in general, and destroy them if they don't have a way to avoid phagocytes. Which would mean that the vast majority of disease due to cellular infection occurs because the disease-causing cells have specifically evolved a way to cause that disease. Is that right?

Okay, to be honest here, the title doesn't really do the actual question justice. For that, I need to add some backstory. I am not very good with studying in the traditional sense(never picked it up and I suffered for it) so the way I would learn things is to put them in a context interesting ienough for them to be retained. As such, I learn most things by imagining what would happen in custom-built scenarios. In this particular case, I was trying to figure out how humans would react to life on another planet. More specifically, what would happen if the native life on the planet had (for whatever reason) originated in a way that caused it to be built of protiens, but otherwise completely alien. Taking it step by step, the first thing (throwing how the life originated out the window) was how unucellular organism that behave much like earth microbes (i.e protien digesting bacteria) would interact with humans. From my understanding, the reason external and internal microbes don't cause us to decompose is because our immune system stops them from doing so. However, there are microbes which our immune system cannot handle whice give us diseases. What I want to ask first, is: is it necessary for our immune system to prepare a specific antibody for every kind of intruder? Are there general purpose antibodies that destroy a wide range of different disease vectors? I realise the question may be vague, and perhaps not even useful. It could be that the type of microbe that exists in the alien life form being affected/not affected by our immune system is totally arbitrary and dependent on how similar or different the alien is from standard earth life. Still, any answer could serve to at least give me a little idea on what kinds of questions I should ask instead.