Immunity may be passive or active. During passive immunity, antibodies made in another person or animal enter the body and the immunity is short-lived and Active Immunity: In the case of active immunity, antigens enter the body and the body responds by making its own antibodies and B-memory cells. In this case, immunity is longer lived although duration depends on the persistence of the antigen and the memory cells in the body. Both passive and active immunity can be either naturally or artificially acquired.
- 13.3A: Naturally Acquired Immunity
- Active naturally acquired immunity refers to the natural exposure to an infectious agent or other antigen by the body. The body responds by making its own antibodies. There are two examples of passive naturally acquired immunity: The placental transfer of IgG from mother to fetus during pregnancy that generally lasts 4 to 6 months after birth; and The IgA and IgG found in human colostrum and milk of babies who are nursed.
- 13.3B: Artificially Acquired Immunity
- Active artificially acquired immunity refers to any immunization with an antigen. During artificially acquired active immunity, one is immunized with one or more of the following: attenuated microbes, killed organisms, fragmented microorganisms, or antigens produced by recombinant DNA technology, or toxoids. Passive artificially acquired immunity refers to the injection of antibody-containing serum, or immune globulin (IG), from another person or animal.