由于疾病和外因引起的免疫系统受损,免疫功能减退,或出现免疫抑制状态,使细胞免疫、体液免疫、吞噬系统和/或补体系统之任何一项受到影响,导致对感染的易感性增加,称为继发性免疫缺陷病(Secondary immunodeficiency,SID)。SID比原发性免疫缺陷病(Premary immunodificiency,PID)更为常见。由于上述后天因素造成的免疫系统损伤可以是暂时性的,也可以是持久性的。其临床表现酷似PID。因为SID常发生在原发病的发生、发展和治疗过程中,因而易被忽略,但因为它能影响原发病的病理过程和预后,所以应引起我们足够的重视。 Impairment of the immune system, immunodeficiency, or immunosuppressive status due to disease and exogenous factors, affecting any of the cellular immunity, humoral immunity, phagocytosis system and / or complement system leads to increased susceptibility to infection, Known as secondary immunodeficiency (Secondary immunodeficiency, SID). SID is more common than primary immunodeficiency (PID). Immune system damage due to these acquired factors can be temporary or permanent. Its clinical manifestations resemble PID. Because SID often occurs in the occurrence, development and treatment of the primary disease, it is easy to be neglected. However, it should be given enough attention because it can affect the pathological process and prognosis of the primary disease.