免疫学是研究当外部事物（例如，病毒，细菌或寄生虫）进入脊椎动物有机体时的生理反应。当代免疫学的范围包含了自我和非自我认同现象的所有方面，包括感染性疾病，器官移植，肿瘤免疫学和自身免疫疾病。
Immunology is the study of the physiological responses which result when foreign materials (e.g. viruses, bacteria or parasites) are introduced into a vertebrate organism such as humans. The scope of modern immunology encompasses all aspects of self vs. non-self recognition phenomena including infectious diseases, organ transplantation, tumour immunology and autoimmune diseases.