Sequential expression of adhesion and costimulatory molecules in graft-versus-host disease target organs after murine bone marrow transplantation across minor histocompatibility antigen barriers.

Graft-versus-host disease (GVHD) is a potentially fatal complication after allogeneic bone marrow transplantation. However, few data exist thus far on the molecular signals governing leukocyte trafficking during the disease. We therefore investigated the sequential pattern of distinct adhesion, costimulatory, and apoptosis-related molecules in GVHD organs (ileum, colon, skin, and liver) after transplantation across minor histocompatibility barriers (B10.D2 --> BALB/c, both H-2d). To distinguish changes induced by the conditioning regimen from effects achieved by allogeneic cell transfer, syngeneic transplant recipients (BALB/c --> BALB/c) and irradiated nontransplanted mice were added as controls. Irradiation upregulated the expression of vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-l, and B7-2 in ileum, as well as VCAM-1 and B7-2 in colon, on day 3 in all animals. Whereas in syngeneic mice these effects were reversed from day 9 on, allogeneic recipients showed further upregulation of VCAM-1, ICAM-1, B7-1, and B7-2 in these organs on day 22, when GVHD became clinically evident. Infiltration of CD4+ and CD8+ donor T cells was noted on day 9 in skin and liver and on day 22 in ileum and colon. Surprisingly, the expression of several other adhesion molecules, such as ICAM-2, platelet-endothelial cell adhesion molecule 1, E-selectin, and mucosal addressin cell adhesion molecule 1, did not change. Proapoptotic and antiapoptotic markers were balanced in GVHD organs with the exception of spleen, in which a preferential expression of the proapoptotic Bax could be noted. Our results indicate that irradiation-induced upregulation of VCAM-1, ICAM-1, and B7-2 provides early costimulatory signals to incoming donor T cells in the intestine, followed by a cascade of proinflammatory signals in other organs once the alloresponse is established.     

Histological changes of bile duct in experimental graft-versus-host disease across minor histocompatibility barriers. I. Light microscopic and immunocytochemical observations

Graft-versus-host disease (GVHD) across minor histocompatibility antigens was developed in mice and the bile duct lesions were surveyed for up to 7.5 months after spleen and bone marrow cell transplantation. Lymphoid cell infiltration was evident by day 3, reached maximum at 2 weeks, then reduced gradually and persisted during the observation period. Fibrous expansion of the portal tracts paralleled with the time after transplantation, but none of the cases progressed into liver cirrhosis. The infiltrates abutted the interlobular and septal bile ducts and distorted their appearance with a frequent infiltration of mononuclear lymphoid cells into the duct epithelial layer. The duct epithelium showed a variety of degenerative and hyperplastic changes, including nuclear enlargement with anisonucleosis, nuclear pyknosis, cytoplasmic and nuclear darkness, cytoplasmic vacuolization, focal epithelial dropout, formation of apoptotic bodies, and micropapillary infolding. Disappearance of the bile ducts and formation of granuloma around the bile ducts were not seen. Immunocytochemical study revealed the exclusive preponderance of helper/inducer T cells in the portal infiltrates and marked expression of I-A antigen on the bile duct epithelium in GVHD mice. These results suggest that immunological mechanisms by helper/inducer T cells against minor histocompatibility antigen on bile duct epithelium in association with class II molecules of MHC are important in the pathogenesis of the bile duct lesions. A putative role of such lymphocytes is discussed.     

Histological changes of bile duct in experimental graft-versus-disease across minor histocompatibility barriers. III. Immunoelectron microscopic observations

Graft-versus-host disease (GVHD) was produced by injecting lymphoid cells from B10.D2 mice into BALB/C mice. Both are H-2-identical but differ only at multiple minor H loci. The expression and localization of MHC class II antigens on the bile duct epithelium was examined using an immunoelectron microscopical method. All GVHD mice developed bile duct lesions of chronic nonsuppurative cholangitis and expressed MHC class II antigens on their bile duct epithelium, while none of the control mice, which injected with the same number of syngeneic lymphocytes, developed bile duct lesions or expressed the antigens. The antigenic expression was characteristically localized on the basolateral surface of the bile duct epithelium but not on the apical surface. Furthermore, the expression varied markedly in its intensity and distribution within the same liver and even within a single bile duct. The infiltration of Lyt-1-positive helper/inducer lymphocytes in the duct epithelial layer apparent by electron microscopy was predominant to a much degree than that of Lyt-2-positive cytotoxic/suppressor lymphocytes and non-lymphocytic cells. The immunological mechanisms involving helper/inducer T cells in association with MHC class II antigens on bile duct epithelium may be important in the induction and progression of the bile duct lesions apparent in the present GVHD model.     

Identification of a novel UTY-encoded minor histocompatibility antigen

Minor histocompatibility antigens (mHags) encoded by the Y-chromosome (H-Y-mHags) are known to play a pivotal role in allogeneic haematopoietic cell transplantation (HCT) involving female donors and male recipients. We present a new H-Y-mHag, YYNAFHWAI (UTY(139-147)), encoded by the UTY gene and presented by HLA-A*24:02. Briefly, short peptide stretches encompassing multiple putative H-Y-mHags were designed using a bioinformatics predictor of peptide-HLA binding, NetMHCpan. These peptides were used to screen for peptide-specific HLA-restricted T cell responses in peripheral blood mononuclear cells obtained post-HCT from male recipients of female donor grafts. In one of these recipients, a CD8+ T cell response was observed against a peptide stretch encoded by the UTY gene. Another bioinformatics tool, HLArestrictor, was used to identify the optimal peptide and HLA-restriction element. Using peptide/HLA tetramers, the specificity of the CD8+ T cell response was successfully validated as being HLA-A*24:02-restricted and directed against the male UTY(139-147) peptide. Functional analysis of these T cells demonstrated male UTY(139-147) peptide-specific cytokine secretion (IFNγ, TNFα and MIP-1β) and cytotoxic degranulation (CD107a). In contrast, no responses were seen when the T cells were stimulated with patient tumour cells alone. CD8+ T cells specific for this new H-Y-mHag were found in three of five HLA-A*24:02-positive male recipients of female donor HCT grafts available for this study.     

Histopathologic sequence of events in adult mice undergoing lethal graft-versus-host reaction developed across H-2 and/or non-H-2 histocompatibility barriers.

The sequence of histologic events in graft-versus-host reaction (GVHR) caused by major and/or minor histoincompatibilities was studied. It was discovered that GVHR may manifest itself in the form of two distinct multiphasic disease entities, depending on whether the donor cells are incompatible with the host for both major and minor histocompatibility antigens ("major GVHR") or for minor histocompatibility antigens alone ("minor GVHR"). The acute or major GVHR has four phases: 1) a transient phase of aplasia, 2) a repopulation phase, 3) a proliferative phase involving lymphoid, presumably immunocompetent, cells, and 4) a phase of acute organ rejection (terminal). The chronic or minor GVHR is characterized by six phases, namely: 1) a transient phase of aplasia, 2) a repopulation phase, 3) a phase of proliferation and tissue infiltration by lymphoid, presumably immunocompetent cells, 4) a phase of major immunologic injuries, 5) a phase of repair, and 6)a terminal phase with advanced sclerosis and proliferative glomerulonephritis. In acute or major GVHR the disease was manifested by the tissue reactions characteristic of acute organ rejection. Lesions were seen in the kidney, liver, bone marrow, lymph nodes, spleen, thymus, intestine, and skin. In the chronic or minor GVHR, tissue injuries were more widespread, affecting the collagen, vessel walls, adipose tissue, renal glomeruli, heart muscle, fascias of skeletal muscles, lymph nodes, spleen, thymus, bone marrow, intestine, skin, esophageal mucosa, and urinary tract. A pronounced plasma cell proliferation was a striking feature in the minor GVHR. Its evolution coincided with advanced thymic epithelial atrophy. It is suggested that the destruction of thymic epithelium resulted in depletion of suppressor T cells and, consequently, in an unopposed proliferation of plasma cells.     

Identification of mimotopes for the H4 minor histocompatibility antigen

The H4 minor histocompatibility antigen (HA) of mice includes a single immunogenic peptide presented by H-2Kb molecules that stimulates skin allograft rejection and is immunodominant in the stimulation of cytolytic T lymphocytes (CTL) specific for multiple minor HA. We have identified H4 mimotopes that are recognized by the H4-specific M9 CTL clone through the use of a random peptide library comprised of bacterial clones expressing an inducible fusion protein tailed with the octamer sequence SXIXFXXL. Eight discrete mimotopes were identified that sensitized RMA-S cells for lysis by M9 CTL down to concentrations of 10(-11) M. Comparable reactivity was observed with a short-term, H4- specific CTL line indicating that the mimotopes were not solely specific for the selecting M9 clone. All mimotopes included Gly at p2 and either Val or Ile at p4, suggesting a requirement for a hydrophobic residue with specific conformation. All mimotopes included either Arg or His at p7, implicating a requirement for a specific positively charged amino acid at that position. The sixth position was more variable with four of eight mimotopes having a Val residue with single mimotopes including alternative amino acids, the majority of which were hydrophobic. Analysis of mimotopes for hydrophobicity and charge by reverse-phase HPLC and capillary electrophoresis respectively indicated that (i) mimotopes with Val at both p4 and p6 were hydrophobically similar (but not identical) to the natural H4 peptide, and (ii) a S --> E substitution at p1 resulted in a peptide (EGIVFVRL) with charge characteristics equivalent to those of the natural H4 peptide.      

Blockade of IL-6-signaling inhibits the pathogenesis of CD4+ T cell-mediated lethal graft-versus-host reaction against minor histocompatibility antigen

Graft-versus-host reaction (GVHR) is considered as a problem in hematopoietic cell transplantation. We found that CD45RB(high) CD62L(+) na?ve CD4(+) T cells from wild-type B10D2 (H-2d MMTV6(-)) mice immediately differentiated into effector T cells producing high-levels of various cytokines after the transfer into BALB/c RAG2(-/-) (H-2d MMTV6(+)) mice. The expanded CD4(+) T cells, which have almost TCR Vβ3 chain, recognized the minor antigen of recipient mice and brought typical severe GVHR symptoms such as eyelid irritation, diarrhea, and liver failure. Eventually, all of the recipient mice transferred CD4(+) T cells was dead within 10 days. We demonstrated here that blockade of IL-6 signaling by administration of anti-IL-6 receptor (IL-6R) monoclonal antibody (mAb) remarkably inhibited the CD4(+) T cell-mediated lethal GVHR. In addition, we confirmed that the in vivo injection of anti-IL-6R mAb prevented the generation of effector CD4(+) T cells which produce the inflammatory cytokines such as IFN-γ, TNF-α, and IL-17. These findings indicated that IL-6 was a critical factor in the CD4(+) T cell-dependent acute GVHR induced by a minor-antigen, suggesting that IL-6-mediated signaling pathway would be a strong therapeutic target in T cell-mediated GVHR as well as other diseases including autoimmune and inflammation.     

Expression of human minor histocompatibility antigen on cultured kidney cells

Incompatibility of human minor histocompatibility (hmH) antigens can induce rejection of grafts in organ transplantation and graft-versus-host reactions in bone marrow transplantation. In spite of their importance in clinical transplantation, hmH antigens are not well studied. Previous studies have demonstrated the expression of hmH antigens on Tand B cells, hematopoietic progenitor cells and keratinocytes. We have for the first time demonstrated the expression of hmH antigens on cultured kidney cells using HLA-B35-restricted, hmH antigen-specific cytotoxic T lymphocyte (CTL) clones, which were previously established from a patient who rejected two kidneys from HLA-identical sisters. The CTL clones could not kill cultured kidney cells. Since cultured kidney cells expressed very low levels of HLA class I antigens it was thought that their failure to be killed by the CTL clones was due to lack of expression of HLA-B35 antigens. After induction of class I antigens on cultured kidney cells by interferon-y (IFN-γ), the IFN-γ-treated cultured kidney cells were killed by the CTL clones. Furthermore, we isolated hmH antigens as peptides from cultured kidney cells after treatment with IFN-γ. These results indicate that cultured kidney cells express hmH antigens when HLA class I antigen is induced by IFN-γ and hmH antigens on cultured kidney cells are recognized by T cells as peptides presented by HLA-B35 molecules.     

Lymphokine production by human milk lymphocytes.

To assess the functional capability of human milk lymphocytes, we studied phytohemagglutinin-induced lymphokine production by breast milk and, for comparison, peripheral blood lymphocyte cultures. Two lymphokines, lymphocyte-derived chemotactic factor (LDCF) and immune interferon, were assayed in supernatants of milk and blood lymphocyte cultures obtained from women 2 to 6 days postpartum. Eleven parallel milk and blood samples were studied for LDCF production. In nine experiments, both milk and blood lymphocytes produced LDCF. In the two other experiments, milk cells did not produce LDCF. In 10 milk cultures studied, all produced interferon activity. Acid and heat lability characteristics were typical of immune interferon. These results further characterize milk lymphocytes as immunologically competent and possibly important effector cells in neonatal immunity.     

Mechanisms involved in graft-versus-host disease induced by the disparity of minor histocompatibility M1s antigens

In this study we investigated which type of T cells: high T-cell receptor (TCRhigh, cells of thymic origin) or intermediate TCR (TCRint, cells of extrathymic origin), expanded in the liver and other organs, resulting in the induction of graft-versus-host disease (GVHD) with minor lymphocyte stimulating (M1s) disparity. When 6.5 Gy-irradiated BALB/c (H-2d M1s-1b2a) mice were injected with interleukin-2 receptor beta-chain(-) (IL-2Rbeta(-)) CD3high cells purified from the spleen of B10.D2 (H-2d M1s-1b2b) mice, IL-2Rbeta(+)CD3high cells expanded in the liver and other organs of recipient mice. The majority of these cells were found to be IL-2Ralpha(-)Mel-14(-)CD4(+)Vbeta3(+) in GVHD mice. The CDR3 region in their TCR-alphabeta (i.e. N-Dbeta-N) was polyclonal, although there were skewed usages of Vbeta3 and Jbeta2.4. The majority of cells were confirmed to be of donor origin by the individual discrimination method, namely, they originated from isolated IL-2Rbeta(-)CD3high cells. Interestingly, these T cells lacked cytotoxicity against both a natural killer (NK)-sensitive target and thymocytes with M1s disparity and nondisparity. Another important finding was that activated granulocytes expanded at generalized sites in GVHD mice. The present results raise the possibility that M1s disparity is mainly recognized by TCRhigh cells with unique properties but that direct effector cells that induce GVHD might not be such T cells but rather accompanied granulocytes.     

Detection of microchimerism by minor histocompatibility antigen HA-1 allele-specific nested polymerase chain reaction.

Minor histocompatibility antigens (mHags) can induce T-cell reactivities with important consequences for the graft-versus-leukemia effect and the development of graft-versus-host disease in HLA-matched stem cell transplantation settings. Recently, mHag-specific T cells were also demonstrated in multiparous woman and in solid organ transplant recipients. Microchimeric cells have been detected in the latter settings. To study whether microchimerism is instrumental in the induction and/or maintenance of mHag T cells, we developed an HA-1 allele-specific nested polymerase chain reaction. To optimize and validate the reliability of this method at different levels of microchimerism, serial dilutions of HA-1(H) cells titrated into HA-1(R) cells were tested. We demonstrated that the HA-1(H) allele can be reliably and consistently detected at concentrations as low as 1:10(5) without losing specificity. The developed HA-1-specific nested polymerase chain reaction is an important tool that facilitates the detection of HA-1 microchimerism in various clinical specimens and that promotes investigation of the effects of microchimerism on induction of mHag-specific T cells in the various settings of immunization.     

Isolation of human minor histocompatibility peptides.

Incompatibility of human minor histocompatibility (hmH) antigens induces rejection of grafts in organ transplantation and graft versus host disease in bone marrow transplantation if donor and recipient are matched for human leukocyte antigen (HLA) genes. These antigens are recognized only by T cells. We describe here the isolation of hmH peptides recognized by a hmH antigen specific, HLA-B35 restricted CTL clone which was derived from a patient who rejected the kidneys from two HLA-identical sisters. Naturally occurring hmH peptides were isolated from a donor derived B cell line and an HLA-B35 transfected human B cell line by acid elution. Analysis of various HLA class I transfectant cells demonstrated that MHC class I molecules themselves determine the peptides which are naturally processed and presented to T cells.     

Power of association test for detecting minor histocompatibility gene causing graft-versus-host disease following bone barrow transplantation

Incompatibility of minor histocompatibility antigen (mHa) is a major cause of acute graft-versus-host disease (GVHD) following bone marrow transplantation in human leukocyte antigen (HLA)-matched donor-recipient pairs. To avoid acute GVHD, as many mHa genes as possible need to be identified . In this study, we introduce a comparison of two proportions as an association test for detecting mHa genes in HLA-matched pairs with and without GVHD. Assuming multiple mHa loci, each with two alleles, we evaluated the effects of (1) minor allele frequency of the mHa locus of interest (denoted by p), and (2) probability of GVHD developing in a donor-recipient pair being incompatible at an mHa locus (denoted by r) on the powers of association tests for unrelated pairs and for sib pairs. Our results showed that based on a candidate gene approach, an mHa gene with high p and r values can be detected by the association test with a small sample size. Application of the present method to the Japanese population revealed that the association test for unrelated pairs is more suitable for detecting an mHa gene with a high r value than that for sib pairs. The present method will be helpful to researchers who evaluate the power of association study in advance.     

A CD8 DE loop peptide analog prevents graft-versus-host disease in a multiple minor histocompatibility antigen-mismatched bone marrow transplantation model.

Donor CD8(+) T cells can be potent mediators of graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation to either major histocompatibility complex (MHC) class I-or multiple minor histocompatibility antigen-mismatched recipients. To develop small molecular inhibitors of CD8(+) T-cell activity, theoretical structural analysis of the human CD8 alpha molecule was previously used to identify potential functional surface epitopes that interact with the MHC class I molecule. The DE loop (p71-78) was identified as such a target region, and a panel of synthetic cyclized peptide mimics of this region were tested for their inhibitory effects on cytotoxic T lymphocyte activity in human cell-mediated lympholysis assays. Peptide 1109 (CKRLGDTFVC) was most effective at inhibiting specific target cell lysis. Accordingly, studies were conducted to determine whether there was sufficient cross-species homology in the DE loop region and its nonpolymorphic interactive site on the beta(2)-microglobulin domain of the MHC class I molecule to allow similar inhibition of murine CD8(+) cytotoxic T lymphocyte activity. On the basis of strong in vitro inhibitory activity of 1109 in the murine system, the capacity of the peptide to inhibit in vivo CD8(+) T-cell effector functions in skin and hematopoietic stem cell transplantation models was examined. In the C57BL/6 anti-bm1 skin allograft rejection model, across an MHC class I barrier, a single injection of 1109 at the time of transplantation significantly prolonged graft survival. Moreover, 1109 administered at the time of transplantation in the multiple minor histocompatibility antigen-disparate B10.BR-->CBA GVHD model significantly prolonged the survival of lethally irradiated mice that underwent transplantation with donor bone marrow cells and CD8(+) T cells. Histopathologic analysis confirmed that mice treated with the synthetic peptide exhibited diminution of epithelial target cell injury. Specificity of the peptide effect was evidenced by draining lymph node cells from B10.BR mice that had been challenged with CBA lymphocytes and simultaneously treated with 1109. These cells could not generate secondary proliferative responses in vitro upon stimulation with CBA splenocytes but could respond to third-party C57BL/6 stimulation. Thus, the 1109 peptide has potential application in the prevention of CD8-mediated GVHD development.     

Genomic identification of the minor histocompatibility antigen HA-1 locus by allele-specific PCR

Abstract: Graft-versus-host disease (GvHD) can be a major complication of allogeneic bone marrow transplantation even in recipients of HLA genotype-identical transplants. Disparities in minor histocompatibility antigens (mHags) between donor and recipient are a potential risk for the development of GvHD. A mismatch for the mHag HA-1 can cause GvHD in adult recipients of allogeneic bone marrow from HLA-identical donors. The mHag HA-1, first identified by HLA -A *0201 -restricted cytotoxic T cells (CTLs), was recently chemically characterized as a nonapeptide. On the cDNA level, the HA-1 locus has two alleles, HA-1^H and HA-1^R, which differ in two nucleotides, resulting in a single amino acid substitution. Here we report on the genomic structure of the HA-1 locus. Isolation and sequencing of cosmid DNA encoding the HA-1 peptide sequence revealed that the HA-1 alleles are encoded by two exons. Two different primer sets were designed, each consisting of allele-specific primers and a common primer, and both sets containing intronic sequences. We performed genomic DNA typing of three families consisting of 24 HLA-A*0201 -positive individuals. The predicted allele-specific products correlated in all cases with the mHag classification by CTLs and by RT-PCR. We demonstrate for the first time the genomic identification of the mHag HA-1 locus. Prospective genomic typing for the HA-1 alleles will improve donor selection and identify HLA-A*0201 -positive recipients with a high risk for HA-1-induced GvHD.