What are antibodies and how do they help?

Bind to site(s). Antibodies (abs) are molecules made to bind to sites on infected cells, bacteria, viral particles, etc. To help the immune system fight disease. For example, monoclonal antibodies bind to the same epitope/site, while polyclonal abs bind to many sites. These can be used in treating cancer and hdnb, autoimmune diseases, like rheumatoid arthritis, and in diagnostic tests, like western blot.