T-cell allorecognition of donor glutathione S-transferase T1 in plasma cell-rich rejection

Abstract

AIMTo investigate the role of glutathione S-transferase T1 donor-specific T lymphocytes in plasma cell-rich rejection of liver allografts.METHODSThe study group included 22 liver transplant patients. Among them, 18 patients were mismatched for the glutathione S-transferase T1 (GSTT1) alleles (don+/rec-), and 4 were matched (don+/rec+). Seven of the mismatched patients produced anti-GSTT1 antibodies and developed plasma cell-rich rejection (former de novo immune hepatitis). For the detection of specific T lymphocytes, peripheral blood mononuclear cells were collected and stored in liquid nitrogen. The memory T cell response was studied by adding to the cell cultures to a mix of 39 custom-made, 15-mer overlapping peptides, which covered the entire GSTT1 amino acid sequence. The specific cellular response to peptides was analyzed by flow cytometry using the markers CD8, CD4, IL-4 and IFNγ.RESULTSActivation of CD8+ T cells with different peptides was observed exclusively in the group of patients with plasma-cell rich rejection (3 out of 7), with production of IL-4 and/or IFNγ at a rate of 1%-4.92% depending on the peptides. The CD4+ response was most common and not exclusive for patients with the disease, where 5 out of 7 showed percentages of activated cells from 1.24% to 31.34%. Additionally, two patients without the disease but with the mismatch had cells that became stimulated with some peptides (1.45%-5.18%). Highly unexpected was the finding of a double positive CD4+CD8low T cell population that showed the highest degree of activation with some of the peptides in 7 patients with the mismatch, in 4 patients with plasma cell-rich rejection and in 3 patients without the disease. Unfortunately, CD4+CD8low cells represent 1% of the total number of lymphocytes, and stimulation could not be analyzed in 9 patients due to the low number of gated cells. Cells from the 4 patients included as controls did not show activation with any of the peptides.CONCLUSIONPatients with GSTT1 mismatch can develop a specific T-cell response, but the potential role of this response in the pathogenesis of plasma cell-rich rejection is unknown.

Rethinking de novo immune hepatitis, an old concept for liver allograft rejection: Relevance of glutathione S-transferase T1 mismatch

“…If this occurs, a subset of these cells will progress to plasma cells and anti-GSTT1 antibodies of the IgG class will be detected concurrently with mature GSTT1-specific CD4 + cells. Our experimental results sustain indirect presentation of the donor GSTT1 protein by recipient APCs[ 56 ].…”

“…These results are particularly significant considering the immunosuppressed status of the patients. In silico analysis of the ability of patients’ HLA class I and class II alleles to present these peptides with optimal percentile ranks supported the experimental results[ 56 ].…”

“…The authors provided the first evidence of memory specific T cells in samples of peripheral blood mononuclear cells (PBMC) of patients after recall with the GSTT1 antigen. Activation of CD8 + and CD4 + T cells with production of IL-4 and/or IFNγ was observed[ 56 ]. Most intriguing was the finding of highly activated CD4 + cells that retained CD8 low expression with a mean value of 25% activated Th0 type cells (3.44%-78.95%).…”

Glutathione S‐Transferase T1 Mismatch Is a Risk Factor for Chronic Ductopenic Rejection of Liver Allografts

“…( 16 ) The presence of specific T cells, activated after recall with GSTT1 peptides, has also been demonstrated, although this finding needs confirmation due to the limited number of samples tested. ( 17 ) The influence of the GSTT1 mismatch in CR has never been explored, which is surprising given that the target cells affected by the immune response in CR are epithelial cells of the bile ducts or cholangiocytes, in the same way that the hepatocytes are the target cells in PC‐rich R. Both cellular types, which are crucial for liver function, express the donor‐encoded GSTT1 enzyme in abundance, ( 15 ) in support of the hypothesis of a potential specific immune response against this antigen in CR. The aim of this study was to explore the predictive value of GSTT1 mismatch in the development of CR.…”