Dietert Rodney R, Piepenbrink Michael S
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
Crit Rev Toxicol. 2006 Apr;36(4):359-85. doi: 10.1080/10408440500534297.
The heavy metal lead is a widely deposited environmental toxicant known to impact numerous physiological systems, including the reproductive, neurological, hepatic, renal, and immune systems. Studies illustrating the capacity of lead to impair immune function and/or host resistance to disease date back to at least the 1960s. However, it has only been in recent years that lead has been recognized among a new category of immunotoxicants-those that dramatically shift immune functional capacity while producing only modest changes to immune cell populations and lymphoid organs. These relatively noncytotoxic immunomodulating chemicals and drugs represent the immunotoxic hazards most difficult to identify and problematic for risk assessment using historic approaches. As a result, such environmental factors are also among the most likely to contribute to chronic immune-related disease at relevant exposure levels. This review considers the animal and human evidence that lead exposure can produce a stark shift in immune functional capacity with a skewing predicted to elevate the risk of atopic and certain autoimmune diseases. At the same time, host defenses against infectious agents and cancer may be reduced. Age-based exposure studies also suggest that levels of blood lead previously thought to be safe, that is, below 10 microg/dl, may be associated with later life immune alterations.
重金属铅是一种广泛沉积的环境毒物，已知会影响包括生殖、神经、肝脏、肾脏和免疫系统在内的众多生理系统。关于铅损害免疫功能和/或宿主抗病能力的研究至少可追溯到20世纪60年代。然而，直到近年来，铅才在一类新的免疫毒物中被认识到，这类毒物能显著改变免疫功能，同时对免疫细胞群体和淋巴器官仅产生适度变化。这些相对无细胞毒性的免疫调节化学物质和药物是最难识别的免疫毒性危害，也是使用传统方法进行风险评估时最成问题的。因此，在相关暴露水平下，这类环境因素也最有可能导致慢性免疫相关疾病。本综述考虑了动物和人类的证据，即铅暴露会导致免疫功能发生明显改变，这种改变预计会增加患特应性疾病和某些自身免疫性疾病的风险。同时，宿主对感染因子和癌症的防御能力可能会降低。基于年龄的暴露研究还表明，以前认为安全的血铅水平，即低于10微克/分升，可能与晚年的免疫改变有关。
