Hubbard W J, Hess A D, Hsia S, Amos D B
J Immunol. 1981 Jan;126(1):292-9.
It has been determined that alpha-2 macroglobulin (alpha 2M) is more suppressive of a mixed lymphocyte response (MLR) when complexed with proteinase than in its "native" state. Other alpha 2M preparations showed a moderate level of MLR suppression, but it is unlikely that this is a result of interaction with cellular proteinases. A panel of other proteinase inhibitors (alpha 1 PI, SBTI, BPTI, TLCK) did not suppress the MLR to the same extent as alpha 2M either when bound with or free from trypsin. A dose-responsive pattern of MLR suppression similar to that observed with purified proteinase-complexed alpha 2M was seen with serum containing proteinase-complexed alpha 2M. The population of cells that apparently conveys the suppressive property is the adherent cells (putative monocytes), which can reduce the MLR almost as well as unfractionated cells when exposed to alpha 2M. Most of these properties of alpha 2M were demonstrable in "serumless" medium with qualitative similarity to the MLR obtained in cultures performed with conventional serum supplemented medium. It was found that alpha 2M-trypsin complexes must be presented at or near culture initiation and remain in contact with the cells for a minimum of approximately 4 hr to have its optimum effect.
已经确定，α-2巨球蛋白（α2M）与蛋白酶结合时比处于“天然”状态时对混合淋巴细胞反应（MLR）的抑制作用更强。其他α2M制剂表现出中等程度的MLR抑制，但这不太可能是与细胞蛋白酶相互作用的结果。一组其他蛋白酶抑制剂（α1PI、SBTI、BPTI、TLCK）与胰蛋白酶结合或游离时，对MLR的抑制程度均不如α2M。含有与蛋白酶结合的α2M的血清呈现出与纯化的与蛋白酶结合的α2M相似的剂量反应性MLR抑制模式。明显具有抑制特性的细胞群体是贴壁细胞（假定的单核细胞），当暴露于α2M时，其对MLR的降低作用几乎与未分离的细胞相同。α2M的这些特性大多在“无血清”培养基中得到证实，与在添加常规血清的培养基中进行的培养所获得的MLR在性质上相似。研究发现，α2M-胰蛋白酶复合物必须在培养开始时或接近培养开始时存在，并与细胞接触至少约4小时才能发挥其最佳效果。
