Immunity It can be defined as the resistance to disease, specifically to infectious disease or pathogens. The term “immune” is derived from the Latin word “immunis” that is exempt from charges. In medical term, it refers to the being protected from infectious pathogens. Immune system It is adaptive defense system which is able to generate a variety of cell and molecules capable of specifically recognizing and eliminating a variety of limitless foreign invaders into the system. In 1975 Georges Kohler and Milstein succeeded in making fusions of myeloma cell lines with B cells to create hybridomas that could produce antibodies. antibody Also known as immunoglobulin is a large, Y shaped glycoprotein produced mainly by plasma cells that is used by the immune system to neutralize pathogens. monoclonal antibodies Antibodies that are made by identical immune cells that are clones of a unique parent cell. polyclonal antibodies A polyclonal antibodies represents a collection of antibodies from different B cells that recognize multiple epitopes on the same antigen.