<Tr> <Td> Cell - mediated and humoral components </Td> <Td> Cell - mediated and humoral components </Td> </Tr> <Tr> <Td> No immunological memory </Td> <Td> Exposure leads to immunological memory </Td> </Tr> <Tr> <Td> Found in nearly all forms of life </Td> <Td> Found only in jawed vertebrates </Td> </Tr> <P> Both innate and adaptive immunity depend on the ability of the immune system to distinguish between self and non-self molecules . In immunology, self molecules are those components of an organism's body that can be distinguished from foreign substances by the immune system . Conversely, non-self molecules are those recognized as foreign molecules . One class of non-self molecules are called antigens (short for antibody generators) and are defined as substances that bind to specific immune receptors and elicit an immune response . </P>

List the four major categories of non specific immunity