These investigations focus on the genetic and biochemical characterization of class I heavy chain specific metalloproteinases (Zn-containing enzymes) and their role in the indirect pathway of allorecognition. Soluble MHC class I antigens are involved in priming CD4+ T cells through the indirect pathway, resulting in rejection of MHC class I disparate grafts. The investigators describe a novel mechanism of generation of soluble MHC class I which operates in activated cells in vitro and in vivo. Free heavy chains originated by disassociation of MHC class I complexes on the cell surface are proteolytically cleaved and released to soluble molecules containing intact extracellular domains and capable of reassociating with beta2 microglobulin in solution, a release mediated by Zn2+ dependent membrane bound metalloproteinase. Much soluble HLA released from the allograft in vivo is dependent upon activity of this enzyme. Three strategies will be used to isolate the appropriate gene. The enzyme substrate relationship between the product of the isolated metalloproteinase gene and free heavy chains will be established, and the role of the metalloproteinase in the indirect pathway of allograft rejection will be tested in mouse skin and rat cardiac allograft models. Animals will be treated with the metalloproteinase inhibitor BB-94 and immune activity assessed.
| Haynes, Lynn D; Waldman, W James; Bushkin, Yuri et al. (2005) CMV-infected allogeneic endothelial cells initiate responder and bystander donor HLA class I release via the metalloproteinase cleavage pathway. Hum Immunol 66:211-21 |
| Dong, Yuzhi; Lieskovska, Jaroslava; Kedrin, Dmitriy et al. (2003) Soluble nonclassical HLA generated by the metalloproteinase pathway. Hum Immunol 64:802-10 |
| Haynes, Lynn D; Bushkin, Yuri; Love, Robert B et al. (2002) Interferon-gamma drives the metalloproteinase-dependent cleavage of HLA class I soluble forms from primary human bronchial epithelial cells. Hum Immunol 63:893-901 |
| Demaria, S; Bushkin, Y (2000) Soluble HLA proteins with bound peptides are released from the cell surface by the membrane metalloproteinase. Hum Immunol 61:1332-8 |
