The five main types of antibodies in the body are IgA, IgD, IgG, IgE, and IgM. They are also known as immunoglobulins. IgG makes up for approximately 70-75% of the antibodies in the human body. Immunoglobulin G can either tag a harmful substance for proteins to identify it, or it may initiate the release of toxins to kill the microorganism. IgM accounts for 10% of human immunoglobulins and are the first antibodies  produced upon an antigen entering the bloodstream. IgA is abundant in serum, nasal mucus, saliva and breast milk, and accounts for 10-15% of immunoglobulins. IgE accounts for 0.001% of human immunoglobulins and its function is to protect against parasites or allergies. IgD accounts for less than 1% of immunoglobulins and its function is to signal the B cells to be activated.