Variable capacity of L3T4+ T cells to cause lethal graft-versus-host disease across minor histocompatibility barriers in mice

A case of chronic GVHD following bone marrow transplantation from a phenotypically HLA-matched unrelated donor

A 45-year-old male with chronic myelocytic leukemia who received a bone marrow transplantation from a phenotypically HLA-matched unrelated donor developed chronic GVHD on day 100 post transplantation. He developed a slight fever, malaise, hepatic dysfunction and extensive itchy erythema with scaling over his entire body. The inflammatory skin lesion developed into erythroderma in about two weeks. H&E staining of a skin biopsy revealed eosinophilic bodies and a lymphocytic infiltration in the dermis and epidermis, which were compatible with the early phases of chronic GVHD. Immunohistochemistry revealed that keratinocytes expressed dense HLA-DR and ICAM-1 epitopes. Langerhans cells (CD1a+ cells) had disappeared from the epidermis. Many T cells (CD3+ cells) had migrated into the epidermis as well as into the reticular dermis. The majority of the T cells in the epidermis were CD8+ cells, while almost all the T cells in the dermis were CD4+ cells. These immunohistochemical features were similar to those previously reported for acute cutaneous GVHD. Despite the corticosteroid therapy, the eruptions did not disappear. The patient was then treated with whole body bath-methoxsalen (Oxsoralen) plus ultraviolet A (UVA). The bath-psoralen plus UVA therapy was effective in this patient.

Role of mast cells in early epithelial target cell injury in experimental acute graft-versus-host disease

The skin is a major target organ for graft-versus-host disease (GVHD), the principal complication of allogeneic bone marrow transplantation. The purpose of the present study was to test whether mast cell degranulation might be related to early target cell injury in the development of acute GVHD. We employed two irradiated murine strain combinations, one in which disease was mediated by CD4+ effector T cells (B10.D2-->DBA/2), and the other by CD8+ effector T cells (B10.BR-->CBA). As compared to controls, both models exhibited mast cell degranulation of differing extents and patterns, as well as dyskeratosis in the epidermis before the influx of effector lymphocytes. These results suggested that factors produced and released by degranulated dermal mast cells might contribute to early target cell injury. Accordingly, the possible role of tumor necrosis factor (TNF)-alpha, a cytokine recently discovered in mast cell granules, was investigated by the injection of anti-TNF-alpha antibody during the course of disease mediated by either CD4+ or CD8+ T cells. Although overall survival of recipients undergoing CD4+ T-cell-mediated GVHD was only slightly improved and the extent of mast cell degranulation was not affected by anti-TNF-alpha antibody treatment, the skin exhibited a significant diminution in the number of dyskeratotic cells/linear mm at 3-4 weeks post-transplantation. In contrast, anti-TNF-alpha antibody failed to enhance survival or reduce the number of dyskeratotic cells in the skin during CD8+ T-cell-mediated disease. Finally, to determine whether CD8+ T-cell-mediated GVHD was at all dependent upon mast cell involvement, the C3H.SW-->B6WWv strain combination was utilized, in which recipients were genetically deficient in mast cells. Onset of GVHD was significantly delayed in B6WWv mice and was clearly correlated to the appearance and increase of de novo mast cells at later time points.

Tissue distribution and polymorphism of minor histocompatibility antigens involved in GVHR

A graft-vs-host reaction (GVHR) develops after major histocompatibility complex (MHC)-compatible bone marrow-transplantation. In the genetic combination studied, B10.D2 donor cells differed from those of (DBA/2 x B10.D2)F1 mice for multiple DBA/2 minor histocompatibility antigens (mHAg) and minor lymphocyte stimulating (Mls) antigens. We investigated the distribution and the cell type expression of mHAg in tissues that were potential GVHR targets, by means of specific T-cell clones derived from mice undergoing reaction. The T-cell clones studied had a CD4+ phenotype and recognized 12 distinct mHAg that were not be product of the Mls-1a gene and that were presented predominantly in association with MHC class II A molecules. Our results indicate that DBA/2 alleles coding for mHAg are frequent in both laboratory and geographically unrelated wild mice. Each mHAg displays an individual pattern of expression on cells present in thymus, skin, gut, and liver. In addition, chimeric mice and established cell lines allowed the identification of cell types expressing mHAg. We found that most mHAg are present on lymphoid and monocyte-macrophage cells, whereas one, distinguished by its absence from lymphoid cells and damaged tissues, is expressed by monocyte-macrophage cells.

Novel approaches to the control of graft versus host disease

Graft versus host disease (GVHD) remains the major obstacle to the application of bone marrow transplantation across HLA barriers. Recent advances in our understanding of GVHD pathophysiology have resulted in the evaluation in animal models and in clinical trials of some novel approaches to avoiding and treating GVHD. Continued advances in our knowledge are likely to result in the clinical application of biological therapies to maximize graft versus leukemia effects and alloengraftment, while avoiding GVHD.

[Immunologic aspects of bone marrow transplantation]

Allogeneic bone marrow transplantation is concerned by immunology by at least two aspects: the first one is the acceptance of the graft by the host and reciprocally and the second one is that it constitutes an unique human model of immune reconstitution. In this review of the immunological aspects, we deal with the selection of the bone marrow donor (related or not) especially on the base of HLA compatibility and the graft-versus-host disease (GVH) with the clinical manifestations, the usual treatments, the supposed cellular mechanisms and the risk factors of developing such complications. The graft versus leukemia effect (GVL) which may be linked to the GVH disease and the mechanisms of rejection and take of the graft are also reviewed as well as the immune reconstitution following the immune deficiency due to the conditioning treatment and the occurrence of a GVH disease.

Roles of CD8+ and CD4+ cells on lethal graft-versus-host disease in nude mice

Roles of CD8+ and CD4+ cells on lethal graft-versus-host disease (GVHD) were investigated. Injection of spleen cells from C57BL/6 (B6) female mice into (BALB/c x B6)F1 nu/nu female mice caused subacute lethal GVHD (survival: 10-50 days). Injection of anti-Lyt-2.2 (CD8) monoclonal antibody (mAb) on days zero, four and 14 into recipient mice prolonged their survival for at least the 200-day observation period. Injection of anti-L3T4 (CD4) mAb also prolonged survival of the mice for more than 70 days, but they eventually died by 150 days. Pretreatment of the donor B6 spleen cells with anti-Lyt-2.2 (CD8) mAb and complement (C) prevented the development of GVHD, and their pretreatment with anti-L3T4 (CD4) mAb and C markedly prolonged the survival of recipient mice. Injection of a mixture of donor spleen cells pretreated with anti-Lyt-2.2 (CD8) mAb and C and those pretreated with anti-L3T4 (CD4) mAb and C induced subacute lethal GVHD. Injection of anti-L3T4 (CD4) mAb, but not anti-Lyt-2.2 (CD8) mAb on days five, nine and 14 prolonged survival of the recipient mice. These results indicated that the collaboration of CD8+ cells and CD4+ cells was necessary for induction of subacute lethal GVHD. CD4+ cells but not CD8+ cells were involved in mediating subacute GVHD from the onset of the disease. CD8+ cells were, however, capable of inducing late-onset lethal GVHD. Direct phenotyping of T cells in the recipient mice revealed that the CD4+ cells were incapable of repopulating without CD8+ cells, but that CD8+ cells were capable of repopulating without CD4+ cells.

Analyses of acute graft-versus-host-like reaction in [MRL/lpr----MRL/+] chimeric mice using MRL/lpr-Thy-1. 1 congenic mice

When MRL/Mp(-)+/+(MRL/+) mice are lethally irradiated and then reconstituted with MRL/Mp-lpr/lpr (MRL/lpr) bone marrow and/or spleen cells, these MRL/+ mice develop "lpr-GVHD" which is similar to acute graft-versus-host disease (GVHD). Using a Thy-1 congenic strain of MRL/lpr mice (MRL/lpr-Thy-1.1), we analyzed T cell subpopulations in the thymus and spleen of MRL/+ mice suffering from lpr-GVHD. lpr-GVHD was induced in MRL/+ mice by transplantation of bone marrow cells (BMC) from MRL/lpr-Thy-1.1 mice; severe lymphocyte depletion associated with fibrosis was observed in the spleens after 7 weeks of bone marrow transplantation (BMT). Thymocytes of the host MRL/+ thymus were replaced with donor-derived cells from the early stage of lpr-GVHD, whereas in the spleen, a small number of host T cells (Thy-1.2+) (4-5%) were retained until the late stage of lpr-GVHD. Donor-type (Thy-1.1+) T cell subsets were not different from those of nontreated MRL/+ mice in the thymus, whereas in the spleen. CD8+ T cells (Thy-1.1+) reached a peak at 5 weeks after BMT, and CD4+ T cells (Thy-1.1+), a peak at 6 weeks. The elimination of T cells from MRL/lpr BMC had no evident effect on the prevention of lpr-GVHD. T cell subpopulations showed a similar pattern to GVHD elicited by MHC differences. Analyses of autoreactive T cells expressing V beta 5 or V beta 11 revealed that autoreactive T cells were deleted from the peripheral lymph nodes. Interestingly, the levels of IgG anti-ssDNA antibodies markedly increased, and both IgM and IgG rheumatoid factors slightly increased 5 to 7 weeks after BMT. These findings are discussed in relation to not only GVHD elicited by MHC differences but also autoimmune diseases.

Cytotoxic folliculitis in GvHD. Evidence of follicular stem cell injury and recovery

Recent observations indicate that stem cells of the murine hair follicle exist exclusively as a subpopulation of relatively undifferentiated outer root sheath cells located in the bulge region at the mid-portion of the follicle. Because it has been hypothesized that stem cells of interfollicular epidermis may represent targets of cytotoxic responses in acute graft-versus-host disease (AGVHD), we studied murine AGVHD and observed sequential skin biopsies for the presence and evolutionary pattern of follicular injury. Highly purified subsets of donor T cells were used to produce AGVHD to multiple minor histocompatibility (H) antigens in two strain combinations of mice matched for the major histocompatibility complex (MHC). In the C3H.SW- greater than B6 strain combination, only CD8+ effector cells produced histologic evidence in skin of AGVHD, which peaked three weeks post-transplant. In the B10.D2- greater than DBA/2 strain combination, CD4+ effector cells, and to a lesser extent, CD8+ cells, mediated disease, which peaked during the fourth week post-transplant. Analysis of skin from both strain/effector cell combinations revealed follicular infiltrates preferentially involving follicular stem cell (FSC) regions (bulge) of anagen follicles between the second and third weeks post-transplant. These infiltrates often preceded infiltration of adjacent interfollicular epidermis and were associated with follicular involution to telogen (resting) phase. By the fourth week post-transplant, greater than 50% of follicles were in telogen phase and residual inflammation was minimal. This provided a unique opportunity to observe follicular recovery from telogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of target injury of murine acute graft-versus-host disease directed to multiple minor histocompatibility antigens elicited by either CD4+ or CD8+ effector cells

The precise identity of effector mononuclear cells capable of eliciting acute graft-versus-host disease (AGVHD) is controversial. In this study, highly purified subsets of donor T cells were used to produce AGVHD to multiple minor histocompatibility (H) antigens in two strain combinations of mice matched for the major histocompatibility complex (MHC). In the C3H.SW- greater than B6 strain combination, only CD8+ effector cells produced histologic evidence of AGVHD in skin and liver, which peaked 3 weeks after transplant. In the B10.D2- greater than DBA/2 strain combination, CD4+ effector cells, and to a lesser extent, CD8+ cells, mediated disease in skin, liver, and intestine, which peaked during the fourth week after transplant. Analysis of skin and liver from both combinations showed target cell injury that was phenotypically similar and resembled that previously described in human disease in other studies. In addition, prominent epithelial injury also was detected in oropharyngeal mucosa, esophagus, hepatobiliary ducts, and seminal vesicle in both transplant settings. These findings indicate that functionally different subsets of donor T cells may be capable of initiating common pathways of cellular injury in selected target sites in AGVHD, and have potential implications for strategies that seek to ablate disease development by manipulation of donor marrow before transplantation.

Prevention of lethal graft-vs.-host disease by a single low dose injection of anti-T cell monoclonal antibody to the allograft recipients

We investigated the capacity of monoclonal antibody (mAb) treatment to prevent graft-vs.-host disease (GVHD) in lethally irradiated, allogeneically reconstituted mice, employing anti-T cell (subset) mAb and a fully allogeneic strain combination. In this strain combination, purified CD4+ cells were able to induce a lethal GVH reaction, whereas purified CD8+ cells were not. In the same strain combination, a single intraperitoneal injection of IgG2b anti-Thy-1 mAb, one day after reconstitution, caused a dose-dependent improvement of the survival. A single injection of a dose as low as 12.5 micrograms per mouse was already effective. Intravenous and intraperitoneal administration of the mAb appeared equally effective. For effective prevention of GVHD the treatment could be postponed until the 4th day after transplantation, but treatment delayed until day 6 was no longer effective. Treatment with IgG2b mAb specific for either helper or cytotoxic T cells also led to improvement of GVHD and survival, but was less effective than treatment with anti-Thy-1 mAb. Clinically, there was a difference in the effectiveness of anti-CD4 and anti-CD8 treatment, since symptoms of GVHD started earlier in the anti-CD8 treated group and the survival was better in the anti-CD4 treated group. These results press for prospective clinical studies employing anti-T cell mAb treatment early after allogeneic bone marrow transplantation, especially in HLA mismatched cases.

Distinct fates of self-specific T cells developing in irradiation bone marrow chimeras: clonal deletion, clonal anergy, or in vitro responsiveness to self-Mls-1a controlled by hemopoietic cells in the thymus

Elimination of potentially self-reactive T lymphocytes during their maturation in the thymus has been shown to be a major mechanism in accomplishing self-tolerance. Previous reports demonstrated that clonal deletion of self-Mls-1a-specific V beta 6+ T lymphocyte is controlled by a radiosensitive I-E+ thymic component. Irradiation chimeras reconstituted with I-E- bone marrow showed substantial numbers of mature V beta 6+ T cells despite host Mls-1a expression. Analysis of the functional properties of such chimeric T cells revealed a surprising variability in their in vitro reactivity to host Mls-1a, depending on the H-2 haplotype of stem cells used for reconstitution. In chimeras reconstituted with B10.S (H-2s) stem cells, mature V beta 6+ lymphocytes were present but functionally anergic to host-type Mls-1a in vitro. In contrast, in chimeras reconstituted with B10.G (H-2q) bone marrow, nondeleted V beta 6+ cells were highly responsive to Mls-1a in vitro. These findings suggest that clonal anergy of V beta 6+ cells to self-Mls-1a may be controlled by the affinity/avidity of T cell receptor interactions with bone marrow-derived cells in the thymus depending on the major histocompatibility complex class II molecules involved. Furthermore, chimeras bearing host (Mls-1a)-reactive V beta 6+ cells did not differ clinically from those with anergic or deleted V beta 6+ cells and survived more than one year without signs of autoimmune disease. Interestingly, their spleen cells had no Mls-1a stimulatory capacity in vitro. Therefore, regulation at the level of antigen presentation may be an alternative mechanism for maintenance of tolerance to certain self-antigens such as Mls-1a.

Dendritic cells stimulate primary human cytolytic lymphocyte responses in the absence of CD4+ helper T cells

Cytotoxic lymphocytes are typically generated from unfractionated suspensions of human lymphocytes by stimulating with heterogeneous APCs and exogeneous growth factors. We have found that human blood dendritic cells can directly stimulate allogeneic human CD8+ T cells to proliferate and express antigen-specific cytotoxic activity. These primary responses, which are accompanied by the release of T cell growth factor(s), are induced in the absence of CD4+ helper T cells and are not inhibited by anti-CD4 mAb. Both antigen-specific CTL as well as nonspecific NK cells can be elicited by dendritic cells. The NK cell response can be depleted at the precursor level by panning with an anti-CD11b mAb, which removes a CD11b+/CD28-, CD16+ subset from the starting CD4- responders. Allogeneic blood monocytes are neither stimulatory nor inhibitory of these primary CD4- MLRs, even though monocytes present alloantigen in such a way as to be recognized as specific targets for CTL that have been sensitized by dendritic cells. The number of CD8+ cells that are blast transformed and express an activated phenotype (i.e., HLA DR/DQ+, CD25/IL-2R+, CD45R-) reaches 30-40% of the culture at day 4-5, the peak of the helper-independent response. We conclude that antigen-presentation by dendritic cells is sufficient in itself to prime cytolytic precursors. We speculate that using dendritic cell stimulators and CD4- responders in MLRs may be more efficient than standard tissue typing approaches for the detection of subtle, but important class I MHC-restricted histoincompatibilities in human transplantation.

Treatment of donor cells with L-leucyl-L-leucine methyl ester prevents induction of graft-vs-host-like reaction in [lpr/lpr----+/+] chimera

Irradiated C57BL/6 (B6) mice which had received spleen cells from autoimmune-prone C57BL/6J-lpr/lpr (B6-lpr) mice underwent a graft-versus-host (GvH)-like reaction early after the spleen cell transfer, although both strains have the same background genes, including MHC and Mls gene, but differ only in a lpr gene. We analyzed the changes in this GvH-like reaction when the donor spleen cells had been treated with L-leucyl-L-leucine methyl ester, which has been reported to have an inhibitory effect on the early GvH reaction in allogeneic or semiallogeneic chimeras. The treatment of donor spleen cells completely abrogated the induction of the early phase of the GvH-like reaction in [B6-lpr----B6] chimeras. The results suggest that the GvH-like reaction in these chimeras is caused by a mechanism(s) similar to that operating in allogeneic or semiallogeneic chimeras.

The effect of T cell depletion from spleen cell allografts on graft-versus-host disease and long-term immune reconstitution in H-2 haplotype-identical murine combinations

Graft-versus-host disease (GVHD) and states of immune reconstitution in allogeneic chimera mice across minor histocompatibility antigens were analyzed in excess of 9 months after injecting AKR/JSea (AKR) spleen cells into irradiated C3H/HeSlc (C3H) mice. When T cell-depleted AKR spleen cells were used as inoculum cells, neither graft failure nor GVHD was seen for 9 months postgrafting in the C3H mice irradiated with 660 rad or more. In an AKR - C3H (850 rad) model, Thy1.1+ or L3T4+ T cell depletion from donor AKR spleen cells abolished both acute and chronic GVHD in lethally irradiated C3H mice. Lyt2+ T cell depletion, however, resulted in acute and chronic GVHD in more than half of the recipient C3H mice. Moreover, actual existence of donor (AKR)-type T cells with L3T4 phenotype, but not Lyt2 phenotype, was always observed in the spleen of the C3H mice suffering from acute GVHD. In addition, the C3H mice that were irradiated with 850 rad, grafted with AKR spleen cells depleted of Lyt2.1+ T cells, escaped from acute GVHD and survived for more than 10 mo postgrafting, showed impaired activities of immune responses such as delayed footpad reaction to sheep red blood cells, antibody production tested by IgM plaque forming cells and reactivity to an intracellular bacterium. Listeria monocytogenes as compared with the C3H mice reconstituted with syngeneic C3H spleen cells or Thy1.1+ or L3T4+ T cell-depleted AKR spleen cells. These results suggest that L3T4+ T cells, rather than Lyt2+ T cells, contained in the grafted cells not only cause acute GVHD but also a long-term immunodeficient state (chronic GVHD) in recipient mice in the H-2-identical murine combinations examined here.

A study on graft-versus-host reaction (GVHR) by Simonsen's splenomegaly assay. Cells and antigen systems involved in induction of GVHR

Cells and histocompatibility antigen systems involved in graft-versus-host reactions (GVHR) were analyzed using Simonsen's splenomegaly assay employing various combinations of donor and F1 hybrid recipients mice. Most of the cells proliferating in spleens of mice undergoing GVHR were J11d+, and had histological features of cells of the hematopoietic lineage. The proportions of CD3+ T cells were decreased in the spleens. Disparity at minor histocompatibility determinants of AKR, I-E and H-2D regions between B10.A(4R) donors and (4R X AKR) F1 recipients evoked only negligible GVHR. On the contrary, disparity at H-2K and/or I-A regions appeared to be sufficient to permit induction of full GVHR. When surface markers of donor spleen cells were analyzed, it was shown that Thy-1+ and/or MEL-14+ cells caused a strong effect on GVHR. Further, either CD4+ or CD8+ T cell subset could induce significant GVHR. However, synergistic influences of these two T cell subsets on one another in GVHR were observed. The present results raise the possibility of using Simonsen's assay along with a number of reagents to identify the contribution of subsets of T lymphocytes and in analyzing precise contributions of cellular components from both donor and recipient, and also of the target antigen systems of the recipient that contribute to early events involved in GVHR.

Long-lasting skin allograft tolerance in adult mice induced across fully allogeneic (multimajor H-2 plus multiminor histocompatibility) antigen barriers by a tolerance-inducing method using cyclophosphamide

A new method of cyclophosphamide (CP)-induced skin allograft tolerance in mice that can regularly overcome fully allogeneic (major H-2 plus non-H-2) antigen barriers in mice has been established. The components of the method are intravenous or intraperitoneal administration of 50-100 micrograms of anti-Thy-1.2 mAb on day -1, intravenous injection of 90 x 10(6) allogeneic spleen cells mixed with 30 x 10(6) allogeneic bone marrow cells from the same donor on day 0, and intraperitoneal injection of 200 mg/kg CP on day 2. In each of four fully allogeneic donor----recipient combinations, including C3H/HeJ (C3H; H-2k)----C57BL/6J(B6; H-2b), B6----C3H, BALB/cByJ (BALB; H-2d)----B6, and BALB----C3H, long-lasting survival of skin allografts was induced in most of the recipient mice. The specific tolerant state induced was dependent on the doses of the antibody and bone marrow cells used. The optimal timing of CP treatment to induce tolerance was found to be 1-3 d after the stimulating cell injection. Treatment with the anti-Thy-1.2 antibody together with CP on day 2 after the cell injection on day 0 also induced profound tolerance. In the B6 mice made tolerant of C3H with antibody, C3H spleen cells plus C3H bone marrow cells, and then CP, a minimal degree of stable mixed chimerism was established and the antitolerogen (C3H) immune responses examined here, including delayed footpad reaction (DFR), CTL activity, and capacity for antibody production against donor-strain antigens were abrogated in a tolerogen-specific manner. From cell transfer experiments, the mechanism of tolerance could be largely attributed to reduction of effector T cells reactive against the tolerogen, and strong suppressive influences that might prolong skin allograft survival directly were not detected in the tolerant mice. Moreover, pretreatment with anti-Thy-1.2 antibody or anti-L3T4 (CD4) antibody was more effective than pretreatment with anti-Lyt-1 (CD5) antibody or anti-Lyt-2 (CD8) antibody as an initial step in tolerance induction. These results suggest that permanent tolerance to fully allogeneic skin grafts may be induced because antibody given before the stimulating cell injection reduces the number of reactive T cells in the recipient mice. This antibody treatment may facilitate an antigen-stimulated destruction of responding and thus proliferating cells with CP by preventing a possibly less proliferative, more rapid maturation of reactive T cells or by destroying residual effector T cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Selective depletion of marrow-T cytotoxic lymphocytes (CD8) in the prevention of graft-versus-host disease after allogeneic bone-marrow transplantation

In vitro depletion of mature pan-T lymphocytes has been widely and successfully used to prevent acute graft-versus-host disease (GVHD) after allogeneic bone-marrow transplantation (BMT). However, this procedure has been associated with a high incidence of graft failure and leukemic relapse. In this pilot study, we evaluated the efficiency of a selective depletion of human marrow T cytotoxic lymphocytes (CD8), a subset essential to induce GVHD in mice. Eleven patients with hematologic malignancies were included (7 HLA-matched BMT, 4 HLA-mismatched BMT). Marrow treatment with 7 anti-CD8 mAbs and rabbit complement resulted in a marked reduction of CD8+ lymphocytes from 15% (median value; range 7%-31%) to 1% (median value; range less than 1%-11%). Acute GVHD was not abolished by this procedure despite postgraft immunosuppression. One patient (HLA-mismatched BMT) rejected his graft and had a full autologous recovery. In conclusion, when compared to the data in the literature, CD8 depletion was shown to be less efficient than pan-T-cell depletion in the prevention of GVHD after allogeneic BMT and was still associated with a major complication associated with this procedure, i.e., graft failure.