natural immunity n immunity that is possessed by a group (as a race, strain, or species) and occurs in an individual as part of its natural biologic makeup and that is sometimes considered to include that acquired passively in utero or from mother's milk or actively by exposure to infection compare ACQUIRED IMMUNITY, ACTIVE IMMUNITY, PASSIVE IMMUNITY
* * *
immunity mediated by cells capable of immune activity without being stimulated by immunization and without antigen specificity, e.g., the activity of NK cells against virus infection and tumor cells.Medical dictionary. 2011.