Identification of Novel MHC Class II-Restricted Male-Specific mHAg Encoded bySMCY (JARID1D)

• Published in: Blood 2009-11, Vol.114 (22), p.1344-1344
• Main Authors: Fujii, Nobuharu, Rosinski, Kellie V, Campregher, Paulo V, Warren, Edus H
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V114.22.1344.1344

Abstract 1344 Poster Board I-366 Male recipients of female hematopoietic cell grafts, when compared with all other donor/recipient gender combinations, have an increased risk for both acute and chronic GVHD, but also have a significantly decreased risk of posttransplant relapse. F→M HCT is also characterized at the cellular level by donor (female) T cell responses against male-specific minor histocompatibility (H-Y) antigens, which can contribute to both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) activity. SMCY is a Y-chromosome gene that has previously been shown to encode at least two distinct MHC class I-restricted H-Y antigens presented by HLA-A*0201 and HLA-B*0702, respectively. Also, association between CD8+ T cell responses specific for the SMCY311-319 FIDSYICQV epitope and GVHD or GVL has been reported. A CD8+ FIDSYICQV-specific T cell clone was also reported to induce histological signs of GVHD reaction in an in vitro skin-explant assay. To date, however, only two MHC class I-restricted, and no MHC class II-restricted, H-Y antigens encoded by SMCY have been characterized. Given the large size of the SMCY and the homologous SMCX proteins and the fact that they are only 85% identical at the amino acid sequence level, we hypothesized that SMCY encodes other MHC class I- and class II-restricted H-Y antigens, and that T cell responses against these epitopes may likewise contribute to GVHD and GVL activity after F→M HCT. Arrays of pentadecapeptides with eleven-residue overlap were designed to tile regions of the SMCY protein that are non-identical to the corresponding regions of its X chromosome-encoded homologue SMCX, and then used to generate SMCY-specific T cell lines recognizing novel SMCY-encoded MHC class I- and class II-restricted H-Y antigens. Peripheral blood mononuclear cells (PBMC) were obtained on posttransplant day +126 from a 46 year-old male patient with monosomy 7 AML who had received a hematopoietic cell graft from his MHC-identical sister, and were stimulated in vitro with dendritic cells derived from his pretransplant PBMC that had been pulsed with the SMCY pentadecapeptides. After three stimulations, a SMCY peptide-specific CD4+ T cell line as well as a SMCY311-319 (FIDSYICQV)-specific CD8+ T cell line were obtained. After cloning by limiting dilution, we further characterized the SMCY-specific CD4+ T cell clone, 13H3. The 13H3 T cell clone recognizes the SMCY232-246 15-mer peptide, ELKKLQIYGPGPKMM, presented by