Antibodies are the proteins (glycoproteins) called immunoglobulins. These are produced by the Jymphocytes in response to entry of a foreign substance or antigen into the body. Lipoproteins are the micellar complex of protein and lipids. Steroids are a group of lipids derived from a saturated compound cyclopentano perhydrophenanthrene, which has a nucleus of four rings. Prostaglandin is a group of organic compounds derived from essential fatty acids and causing a range of physiological effects in animals.