Forssman antigen-An antigen is a substance that is capable of inducing an immune response to it. For example, when we have any type of immunisation (eg., flu vaccine, MMR, etc.), we are having antigens injected into our body, so that the immune system can process this vaccine and prepare itself for the genuine disease, if we are unlucky enough to be exposed to it at a later date. The vaccine contains "weakened" microbes, or their parts so that they are not virulent (strong) enough to harm us, yet effective enough to cause the immune system to recognise them as foreign. The immune system responds to the introduction of a vaccine by produces antibodies. Antibodies are proteins capable of binding and neutralising suspected threats introduced into the body. Therefore, anything that causes the immune system to manufacture antibodies can be called an "antigen". Theoretically, there is virtually an unlimited number of antigens, considering the amount of chemicals that can be synthesized. Additionally, things are not normally antigenic can be made antigenic under certain conditions (eg., inducing substances)

The Forssman antigen is an antigen as well, discovered by the physician Werner Forssman. We introduce the Forssman antigen here, because it is an example of a ceramide. Inerestingly, this ceramide happens to act as as antigen, stimulating an immune response into the animal of choice that it was injected into. The Forssman antigen (maybe we should call it the Forssman ceramide) is an antigen taken from several unrelated animal serums, but can include sheep, guinea pigs, etc. The Forssman antigen is something of an academic interest of past science and thus, we've included it for you, to show you the applicability of lipids and their varied importance.