Immunol Lett. 2012 Feb 29;142(1-2):75-7. doi: 10.1016/j.imlet.2011.10.013. Epub 2011 Nov 26.
During antibody synthesis, immunoglobulin light chains are produced in excess of heavy chains and, as a consequence, can be secreted by plasma cells as free light chains (FLC). Thus, FLC were considered to be a by-product of immunoglobulin synthesis, lacking any biological function or relevance. However, mounting evidence suggests that FLC are bioactive molecules. For example, FLC can induce antigen specific type I hypersensitivity and inhibit viral replication in encephalomyocarditis infected mice. We have recently shown that FLC can associate with the outer membrane of certain plasma cells via interaction with saturated phosphocholine lipids such as sphingomyelin. As these lipids are highly abundant in mammalian cell membranes, we set out to determine whether FLCs can bind to membranes from a variety of cell types. We found that FLCs bind to the plasma membrane of cells from a wide range of lineages. Interestingly, the highest level of binding was to monocytes. As these cells are professional antigen presenting cells, we postulate that membrane-associated FLCs may provide a novel mechanism of antigen uptake by these cells.
在抗体合成过程中，免疫球蛋白轻链的产量超过重链，因此可以由浆细胞作为游离轻链 (FLC) 分泌。因此，FLC 被认为是免疫球蛋白合成的副产物，缺乏任何生物学功能或相关性。然而，越来越多的证据表明 FLC 是具有生物活性的分子。例如，FLC 可以诱导抗原特异性 I 型超敏反应，并抑制脑炎心肌炎感染小鼠中的病毒复制。我们最近表明，FLC 可以通过与鞘磷脂等饱和磷酰胆碱脂质相互作用与某些浆细胞的外膜结合。由于这些脂质在哺乳动物细胞膜中含量非常丰富，我们着手确定 FLC 是否可以与来自多种细胞类型的膜结合。我们发现 FLC 与来自广泛谱系的细胞的质膜结合。有趣的是，结合程度最高的是单核细胞。由于这些细胞是专业的抗原呈递细胞，我们推测膜结合的 FLC 可能为这些细胞提供了一种新的抗原摄取机制。
