Sipione Simonetta, Simmen Katia C, Lord Sarah J, Motyka Bruce, Ewen Catherine, Shostak Irene, Rayat Gina R, Dufour Jannette M, Korbutt Greg S, Rajotte Ray V, Bleackley R Chris
Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
J Immunol. 2006 Oct 15;177(8):5051-8. doi: 10.4049/jimmunol.177.8.5051.
Sertoli cells have long since been recognized for their ability to suppress the immune system and protect themselves as well as other cell types from harmful immune reaction. However, the exact mechanism or product produced by Sertoli cells that affords this immunoprotection has never been fully elucidated. We examined the effect of mouse Sertoli cell-conditioned medium on human granzyme B-mediated killing and found that there was an inhibitory effect. We subsequently found that a factor secreted by Sertoli cells inhibited killing through the inhibition of granzyme B enzymatic activity. SDS-PAGE analysis revealed that this factor formed an SDS-insoluble complex with granzyme B. Immunoprecipitation and mass spectroscopic analysis of the complex identified a proteinase inhibitor, serpina3n, as a novel inhibitor of human granzyme B. We cloned serpina3n cDNA, expressed it in Jurkat cells, and confirmed its inhibitory action on granzyme B activity. Our studies have led to the discovery of a new inhibitor of granzyme B and have uncovered a new mechanism used by Sertoli cells for immunoprotection.
支持细胞长期以来因其抑制免疫系统以及保护自身和其他细胞类型免受有害免疫反应影响的能力而被人们所认识。然而，支持细胞产生这种免疫保护的确切机制或产物从未得到充分阐明。我们研究了小鼠支持细胞条件培养基对人颗粒酶B介导的杀伤作用的影响，发现存在抑制作用。随后我们发现，支持细胞分泌的一种因子通过抑制颗粒酶B的酶活性来抑制杀伤作用。SDS-PAGE分析表明，该因子与颗粒酶B形成了一种SDS不溶性复合物。对该复合物进行免疫沉淀和质谱分析，确定了一种蛋白酶抑制剂丝氨酸蛋白酶抑制剂3N（serpina3n）是一种新型的人颗粒酶B抑制剂。我们克隆了serpina3n cDNA，在Jurkat细胞中表达，并证实了其对颗粒酶B活性的抑制作用。我们的研究发现了一种新的颗粒酶B抑制剂，并揭示了支持细胞用于免疫保护的一种新机制。
