title: Identification of a novel human granzyme B inhibitor secreted by cultured sertoli cells.
abstract: 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.
authors.affiliation: Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Sipione
authors.forename: Katia C
authors.initials: KC
authors.lastname: Simmen
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Lord
authors.forename: Bruce
authors.initials: B
authors.lastname: Motyka
authors.forename: Catherine
authors.initials: C
authors.lastname: Ewen
authors.forename: Irene
authors.initials: I
authors.lastname: Shostak
authors.forename: Gina R
authors.initials: GR
authors.lastname: Rayat
authors.forename: Jannette M
authors.initials: JM
authors.lastname: Dufour
authors.forename: Greg S
authors.initials: GS
authors.lastname: Korbutt
authors.forename: Ray V
authors.initials: RV
authors.lastname: Rajotte
authors.forename: R Chris
authors.initials: RC
authors.lastname: Bleackley
mesh_terms: D000209:Acute-Phase Proteins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D000818:Animals; D001685:Biological Factors / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D053804:Granzymes / Q000037:antagonists & inhibitors*; D006801:Humans; D007107:Immune System; D019169:Jurkat Cells; D008297:Male; D051379:Mice; D011485:Protein Binding; D015843:Serpins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
chemical_list: D000209:Acute-Phase Proteins; D001685:Biological Factors; C516624:Serpina3n protein, mouse; D015843:Serpins; D053804:Granzymes