CD8+ cytotoxic T lymphocytes isolated from allogeneic healthy donors recognize HLA class Ia/Ib-associated renal carcinoma antigens with ubiquitous or restricted tissue expression

Allogeneic hematopoietic stem cell transplantation can induce considerable tumor remissions in metastatic renal-cell carcinoma (RCC) patients. The precise effector mechanisms mediating these graft-versus-tumor reactions are unknown. We studied RCC-directed CD8(+) T-cell responses in blood lymphocytes of healthy individuals matched with established RCC cell lines for HLA-class I. In 21 of 22 allogeneic mixed lymphocyte/tumor-cell cultures (MLTCs), RCC-reactive cytotoxic T-lymphocytes (CTLs) were readily obtained. From MLTCs, 121 CD8(+) CTL clones with memory phenotype were isolated. Their anti-RCC reactivity was restricted by multiple classical HLA-la molecules, in particular by HLA-A2, -A3, -B7, -B44, -Cw7, and by a nonclassical HLA-Ib determinant. Extensive cross-reactivity analyses on a broad target panel identified CTLs that recognize antigens with expression restricted to renal tissue or to renal and colon tumors. Other CTLs were directed against antigens with broader tissue distribution being expressed in various epithelial and nonepithelial tumors or, additionally, in hematopoietic cells. With microcapillary liquid chromatography and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF)/TOF mass spectrometry, we identified the HLAA*0301-associated nonpolymorphic peptide KLPNSVLGR encoded by the ubiquitously expressed Eps15 homology domain-containing 2 gene as a CTL target. Defining human IRCC antigens recognized by alloreactive CTLs may allow to improve the specificity and efficiency of allogeneic cell therapy (eg, specific donor-lymphocyte infusions or vaccination) in metastatic RCC patients

Aberrant expression of the hematopoietic-restricted minor histocompatibility antigen LRH-1 on solid tumors results in efficient cytotoxic T cell-mediated lysis.

Contains fulltext : 79614.pdf (publisher's version ) (Closed access)CD8(+) T cells recognizing minor histocompatibility antigens (MiHA) on solid tumor cells may mediate effective graft-versus-tumor (GVT) reactivity after allogeneic stem cell transplantation (SCT). Previously, we identified LRH-1 as a hematopoietic-restricted MiHA encoded by the P2X5 gene. Here, we report that LRH-1 is aberrantly expressed on solid tumor cells. P2X5 mRNA expression is demonstrated in a significant portion of solid tumor cell lines, including renal cell carcinoma (RCC), melanoma, colorectal carcinoma, brain cancer and breast cancer. Importantly, P2X5 gene expression was also detected in a subset of primary solid tumor specimens derived from RCC, brain cancer and breast cancer patients. Furthermore, P2X5 expressing solid tumor cells can be effectively targeted by LRH-1-specific cytotoxic T lymphocytes under inflammatory conditions. The expression of HLA-B7 and CD54 on tumor cells increases upon cytokine stimulation resulting in improved T cell activation as observed by higher levels of degranulation and enhanced tumor cell lysis. Overall, hematopoietic-restricted MiHA LRH-1 is aberrantly expressed on solid tumor cells and may be used as target in GVT-specific immunotherapy after SCT

Restriction of Porcine Endogenous Retrovirus by Porcine APOBEC3 Cytidine Deaminases ▿

Xenotransplantation of porcine cells, tissues, and organs shows promise to surmount the shortage of human donor materials. Among the barriers to pig-to-human xenotransplantation are porcine endogenous retroviruses (PERV) since functional representatives of the two polytropic classes, PERV-A and PERV-B, are able to infect human embryonic kidney cells in vitro, suggesting that a xenozoonosis in vivo could occur. To assess the capacity of human and porcine cells to counteract PERV infections, we analyzed human and porcine APOBEC3 (A3) proteins. This multigene family of cytidine deaminases contributes to the cellular intrinsic immunity and act as potent inhibitors of retroviruses and retrotransposons. Our data show that the porcine A3 gene locus on chromosome 5 consists of the two single-domain genes A3Z2 and A3Z3. The evolutionary relationships of the A3Z3 genes reflect the evolutionary history of mammals. The two A3 genes encode at least four different mRNAs: A3Z2, A3Z3, A3Z2-Z3, and A3Z2-Z3 splice variant A (SVA). Porcine and human A3s have been tested toward their antiretroviral activity against PERV and murine leukemia virus (MuLV) using novel single-round reporter viruses. The porcine A3Z2, A3Z3 and A3Z2-Z3 were packaged into PERV particles and inhibited PERV replication in a dose-dependent manner. The antiretroviral effect correlated with editing by the porcine A3s with a trinucleotide preference for 5′ TGC for A3Z2 and A3Z2-Z3 and 5′ CAC for A3Z3. These results strongly imply that human and porcine A3s could inhibit PERV replication in vivo, thereby reducing the risk of infection of human cells by PERV in the context of pig-to-human xenotransplantation