title: Evidence for Induced Expression of HLA Class II on Human Islets: Possible Mechanism for HLA Sensitization in Transplant Recipients.
abstract: Recent reports have shown that islet transplant recipients develop antibodies against donor human leukocyte antigen (HLA) class I and II. Because human islets do not express HLA class II under normal conditions, mechanisms underlying induction of the anti-class II response are unclear. We hypothesized that under inflammatory conditions, islets will have induced expression of HLA class II leading to sensitization. Isolated human islets were divided into two groups. Group 1 was cultured at 37 degrees C as control; group 2 was cultured similarly in presence of tumor necrosis factor alpha and interferon gamma. After treatment, islets were analyzed for expression of HLA class II using real-time polymerase chain reaction, immunofluorescence and flow cytometry. Furthermore, serum from an islet transplant recipient who developed anti-class II antibody was tested by flow cytometry for immunoglobulin (Ig) binding to cytokine-stimulated islets. Real-time polymerase chain reaction analysis for gene transcripts of class II transactivator, HLA-DRagr;, and HLA-DRbeta1 showed maximum 9.38-, 18.95-, and 46.5-fold increase, respectively in group 2 when compared with control at 24 hr. Cytokine treatment increased HLA class II expression markedly on both alpha and beta cells in islets as evidenced by fluorescent imaging and flow cytometric analysis. When patient serum was analyzed by flow cytometry, both IgM and IgG binding was observed in cytokine-treated, HLA class II matched islet cells alone. We conclude that inflammation leads to induced expression of HLA class II on transplanted islet cells potentially causing antidonor sensitization and adversely impacting islet transplant outcomes.
authors.affiliation: Baylor Regional Transplant Institute, Baylor University Medical Center, Dallas, TX, USA.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Jackson
authors.forename: John E
authors.initials: JE
authors.lastname: Connolly
authors.forename: Shinichi
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Noguchi
authors.forename: Nicholas
authors.initials: N
authors.lastname: Onaca
authors.forename: Marlon F
authors.initials: MF
authors.lastname: Levy
authors.forename: Bashoo
authors.initials: B
authors.lastname: Naziruddin
mesh_terms: D002478:Cells, Cultured; D003470:Culture Media; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology; D050416:Glucagon-Secreting Cells / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology*; D006684:HLA-DR Antigens / Q000235:genetics; D015809:HLA-DR7 Antigen / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D006801:Humans; D007114:Immunization; D050417:Insulin-Secreting Cells / Q000276:immunology; D007371:Interferon-gamma / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology / Q000276:immunology*; D016381:Islets of Langerhans Transplantation / Q000276:immunology*; D007519:Isoantigens / Q000097:blood; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D003470:Culture Media; D006680:HLA Antigens; D006684:HLA-DR Antigens; D015809:HLA-DR7 Antigen; D000949:Histocompatibility Antigens Class II; D007519:Isoantigens; D014409:Tumor Necrosis Factor-alpha; D012313:RNA; D007371:Interferon-gamma