Sonnenfeld G
Department of General Surgery Research, Carolinas Medical Center, Charlotte, NC, USA.
Int J Sports Med. 1998 Jul;19 Suppl 3:S195-202; discussion S202-4. doi: 10.1055/s-2007-971992.
Space flight has been shown to have profound effects on immunological parameters of humans, monkeys and rodents. These studies have been carried out by a number of different laboratories. Among the parameters affected are leukocyte blastogenesis, natural killer cell activity, leukocyte subset distribution, cytokine production - including interferons and interleukins, and macrophage maturation and activity. These changes start to occur only after a few days space flight, and some changes continue throughout long-term space flight. Antibody responses have received only very limited study, and total antibody levels have been shown to be increased after long-term space flight. Several factors could be involved in inducing these changes. These factors could include microgravity, lack of load-bearing, stress, acceleration forces, and radiation. The mechanism(s) for space flight-induced changes in immune responses remain(s) to be established. Certainly, there can be direct effects of microgravity, or other factors, on cells that play a fundamental role in immune responses. However, it is now clear that there are interactions between the immune system and other physiological systems that could play a major role. For example, changes occurring in calcium use in the musculoskeletal system induced by microgravity or lack of use could have great impact on the immune system. Most of the changes in immune responses have been observed using samples taken immediately after return from space flight. However, there have been two recent studies that have used in-flight testing. Delayed-type hypersensitivity responses to common recall antigens of astronauts and cosmonauts have been shown to be decreased when tested during space flights. Additionally, natural killer cell and blastogenic activities are inhibited in samples taken from rats during space flight. Therefore, it is now clear that events occurring during space flight itself can affect immune responses. The biological significance of space flight-induced changes in immune parameters remains to be established; however, as duration of flights increases, the potential for difficulties due to impaired immune responses also increases.
太空飞行已被证明会对人类、猴子和啮齿动物的免疫参数产生深远影响。这些研究由多个不同实验室进行。受影响的参数包括白细胞增殖、自然杀伤细胞活性、白细胞亚群分布、细胞因子产生（包括干扰素和白细胞介素）以及巨噬细胞成熟和活性。这些变化仅在太空飞行几天后开始出现，并且一些变化在长期太空飞行过程中持续存在。抗体反应仅得到了非常有限的研究，并且已表明长期太空飞行后总抗体水平会升高。诱导这些变化可能涉及几个因素。这些因素可能包括微重力、缺乏负重、压力、加速力和辐射。太空飞行诱导免疫反应变化的机制仍有待确定。当然，微重力或其他因素可能对在免疫反应中起基本作用的细胞有直接影响。然而，现在很清楚的是，免疫系统与其他生理系统之间的相互作用可能起主要作用。例如，微重力或缺乏使用导致的肌肉骨骼系统钙利用变化可能对免疫系统有很大影响。免疫反应的大多数变化是在太空飞行返回后立即采集的样本中观察到的。然而，最近有两项研究使用了飞行中测试。已表明宇航员和航天员在太空飞行期间接受测试时，对常见回忆抗原的迟发型超敏反应会降低。此外，在太空飞行期间从大鼠采集的样本中，自然杀伤细胞和增殖活性受到抑制。因此，现在很清楚，太空飞行本身发生的事件会影响免疫反应。太空飞行诱导的免疫参数变化的生物学意义仍有待确定；然而，随着飞行时间的增加，免疫反应受损导致困难的可能性也会增加。
