Lysozyme which is found in the lysosomes. They function at a relatively low pH and are so because if they functioned at physiological pH they would digest the cell. But in this case, they are in the lysosomes where they are safe and at a lower pH so when the vesicles open they can emit hydrogen ions and the lysozyme to digest the foreign material.
Antibodies, also called immunoglobulins, are proteins manufactured by the body that help fight against foreign substances called antigens. When an antigen enters the body, it stimulates the immune system to produce antibodies. (The immune system is the body's natural defense system.) The antibodies attach, or bind, themselves to the antigen and inactivate it.<span>
Read more: <span>http://www.scienceclarified.com/Al-As/Antibody-and-Antigen.html#ixzz4YlY105DD</span></span>
An anterior pituitary gland