A new study published in the Journal of Nature Communications, has revealed how exactly our immune system works. Researchers have said that our immune system relies on nanomachines that can open deadly holes in their targets, to kill bacteria in the blood. During this process, a key bottleneck helps to protect our own cells. Our immune system is a complex network of cells, tissues, and organs that work together to defend against germs. It helps your body to recognize these foreign invaders and destroy them. In case your defense system is weak or too active and cannot do its job properly, your body will become vulnerable to various diseases and conditions like allergy, asthma, autoimmune diseases like rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis etc. There are some common symptoms that you experience when your immune system is not working the way it should be. Read on to know about those signs.