I am allergic to dust, due to the particles being so fine.
Same here, I hate having allergies!
Are your alergiesd caused by hypersensitivity of the immune system also?
I think it is a combination of both, but I am not positive.  I do get sick a lot.  
The immune system is a host defense system, that protects use against disease.
Is there anything I can do to boost my immune system?
I am not sure but for an immune system to function properly it must detect a wide variety of pathogens.
I have taken a lot of antibiotics, so that may have messed my immune system up.
Hopefully the antibiotics kill the growth of bacteria like they are intended to.
I have heard they can mess up the good bacteria as well.  Does vitamin c help?