Exosomes are tiny, spherical packages of information that cells exchange with each other to communicate. Tiny, but not small. Information inside of cells is stored using protein chains. If an individual protein is one sentence, an exosome is like an entire book. Scientists used to think that these books were just garbage cans were all the unused proteins were collected and shipped out. But after more careful examination, researchers at the West Virginia University School of Medicine found there's more to these cans than meets the eye.
Exosomes were believed to provide a snapshot of everything there was in the cell. But when researchers examined exosomes shipped out by melanoma cancer cells, they discovered that not all information was shipped out. These cells selected which proteins to include in the package.
Our bodies are filled with a type of immune cells called T cells. Each T cell recognizes a specific pattern. If a T cell identifies a pattern that should not be in the body, it quickly multiplies. The generated army then swarms the envading cell and destroys it. That is how the flu viruses get destroyed. Under healthy conditions, even melanoma cells would be identified and destroyed. But in sick people, melanoma cells withhold specific patterns of information from the exosome been shipped out, so that T cells would not recognize them as an envader.
Researchers hope this discovery will help create drugs that will help the immune system fight cancer cells. The really important take away from this though is that our immune system is able to fight even cancer cells, when it's healthy. So keeping your immune system healthy is a much better bet than hoping some replicated functionality of the immune system stored in a drug will help you once something goes wrong.