Specificity of T cells invading the skin during acute graft-vs.-host disease after semiallogeneic bone marrow transplantation

GVHD Pathogenesis, Prevention and Treatment: Lessons From Humanized Mouse Transplant Models

Graft-vs-host disease (GVHD) is the most common cause of non-relapse mortality following allogeneic hematopoietic stem cell transplantation (HSCT) despite advances in conditioning regimens, HLA genotyping and immune suppression. While murine studies have yielded important insights into the cellular responses of GVHD, differences between murine and human biology has hindered the translation of novel therapies into the clinic. Recently, the field has expanded the ability to investigate primary human T cell responses through the transplantation of human T cells into immunodeficient mice. These xenogeneic HSCT models benefit from the human T cell receptors, CD4 and CD8 proteins having cross-reactivity to murine MHC in addition to several cytokines and co-stimulatory proteins. This has allowed for the direct assessment of key factors in GVHD pathogenesis to be investigated prior to entering clinical trials. In this review, we will summarize the current state of clinical GVHD research and discuss how xenogeneic HSCT models will aid in advancing the current pipeline of novel GVHD prophylaxis therapies into the clinic.

The doubling potential of T lymphocytes allows clinical-grade production of a bank of genetically modified monoclonal T-cell populations

BACKGROUND AIMS

To produce an anti-leukemic effect after hematopoietic stem cell transplantation we have long considered the theoretical possibility of using banks of HLA-DP specific T-cell clones transduced with a suicide gene. For that application as for any others, a clonal strategy is constrained by the population doubling (PD) potential of T cells, which has been rarely explored or exploited.

METHODS

We used clinical-grade conditions and two donors who were homozygous and identical for all HLA-alleles except HLA-DP. After mixed lymphocyte culture and transduction, we obtained 14 HLA-DP-specific T-cell clones transduced with the HSV-TK suicide gene. Clones were then selected on the basis of their specificity and functional characteristics and evaluated for their doubling potential.

RESULTS

After these steps of selection the clone NAT-DP4^(TK), specific for HLA-DPB1*04:01/04:02, which produced high levels of interferon-γ (IFNγ), tumor necrosis factor (TNF), interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF), was fully sequenced. It has two copies of the HSV-TK suicide transgene whose localizations were determined. Four billion NAT-DP4^(TK) cells were frozen after 50 PDs. Thawed NAT-DP4^(TK) cells retain the potential to undergo 50 additional PDs, a potential very far beyond that required to produce a biological effect. This PD potential was confirmed on 6/16 additional different T-cell clones. This type of well-defined clone can also support a second genetic modification with CAR constructs.

CONCLUSION

The possibility of choosing rare donors and exploiting the natural proliferative potential of T lymphocytes may dramatically reduce the clinical and immunologic complexity of adoptive transfer protocols that rely on the use of third-party T-cell populations.

HLA class II upregulation during viral infection leads to HLA-DP-directed graft-versus-host disease after CD4+ donor lymphocyte infusion

CD8+ T cell-depleted (TCD) donor lymphocyte infusion (DLI) after TCD allogeneic hematopoietic stem cell transplantation (alloSCT) has been associated with a reduced risk of graft-versus-host disease (GVHD) while preserving conversion to donor hematopoiesis and antitumor immunity, providing a rationale for exploring CD4+ T cell-based immunotherapy for hematologic malignancies. Here, we analyzed the clinical course and specificity of T cell immune responses in 2 patients with acute myeloid leukemia (AML) who converted to full-donor chimerism but developed severe acute GVHD after prophylactic CD4+ DLI after 10/10-HLA-matched, but HLA-DPB1-mismatched TCD-alloSCT. Clonal analysis of activated T cells isolated during GVHD demonstrated allo-reactivity exerted by CD4+ T cells directed against patient-mismatched HLA-DPB1 molecules on hematopoietic cells and skin-derived fibroblasts only when cultured under inflammatory conditions. At the time of CD4+ DLI, both patients contained residual patient-derived T cells, including cytomegalovirus (CMV)-specific T cells as a result of CMV reactivations. Once activated by CMV antigens, these CMV-specific T cells could stimulate HLA-DPB1-specific CD4+ T cells, which in turn could target nonhematopoietic tissues in GVHD. In conclusion, our data demonstrate that GVHD after HLA-DPB1-mismatched CD4+ DLI can be mediated by allo-reactive HLA-DPB1-directed CD4+ T cells and that ongoing viral infections inducing HLA class II expression on nonhematopoietic cells may increase the likelihood of GVHD development. This trial is registered at http://www.controlled-trials.com/ISRCTN51398568/LUMC as #51398568.

Lymphocytes, cytokines and adhesion molecules in chronic graft versus host disease

Aims-To determine which inflammatory and immune pathways are implicated in the development of chronic graft versus host disease (GvHD) and whether differences between these pathways are responsible for the different presentations of chronic GvHD.Methods-Biopsy specimens of diseased and normal skin were obtained from patients presenting with lichen planus-like and sclerodermatous type chronic GvHD. Expression of epidermal cytokines, adhesion molecules and lymphoid surface markers was analysed by means of immunohistochemistry. Apoptosis was detected using the in situ nick endlabelling method.Results-In both GvHD lesion types, CD8+ cells predominated in the epidermis, whereas CD4+ cells were the most prevalentin the dermis. Apoptotickeratinocytes were found in diseased skin only and Fas antibodies labelled a considerable number of keratinocytes. The epidermis in both types of lesions expressed interleukin (IL) 1alpha, tumour necrosis factor (TNF) alpha and intercellular adhesion molecule (ICAM)-1, but dermal vascular cell adhesion molecule (VCAM)-1 expression was restricted to specimens of lichen planus-like GvHD. IL1alpha and E-selectin were expressed in normal looking skin of 55% and 80%, respectively, of patients with lichen planus-like GvHD.Conclusion-The similarity between expression of epidermal cytokines and adhesion molecules (with the exception of VCAM-1) and lymphocyte phenotype in lichen planus-like and sclerodermatous GvHD strongly suggests that the latter occurs as a consequence of the healing process. VCAM-1 distinguishes between lichen planus-like and sclerodermatous lesions. IL1alpha and E-selectin are potential early markers of chronic GvHD.

Preparation of Genetically Homogeneous Antigen-Specific Thymidine Kinase Positive T-Lymphocyte Clones for the Control of Alloreactivity Post-Bone Marrow Transplantation

We have previously proposed the use of HLA-specific T-cell clones transduced with a suicide gene to produce an allogeneic effect that can be controlled after allogeneic bone marrow transplantation. Procedures described so far to obtain specific T-cells transduced with a suicide gene have led to the recovery of heterogeneous polyclonal T-cells with a limited level of purity. We have therefore developed an approach to select specific T-cell clones in which the suicide transgene is inserted at a unique site of the genome, and used it to produce CD(+)-cytotoxic HLA-DP-specific T-cell clones. Immunization was performed by a one-way mixed lymphocyte culture and responder T lymphocytes were transduced at day 16, 6 days after the second stimulation. Transductions were carried out using gibbon ape leukemia virus (GALV)-pseudotyped retroviral particles harboring a bicistronic Thy-1/TK vector produced by TEFLY GA16-pKM4 clone 34 packaging cells. Three to 5 days later, CD90 immunomagnetic selection and cloning were performed on the transduced T cells. Our results demonstrate that this procedure led to the recovery of T-cell clones, the majority of which had the expected specificity and a single site of transgene insertion. Such clonotransgenic T-cell populations represent suitable tools to drive a defined alloreaction that can be controlled after bone marrow transplantation.

Nephrotic syndrome with crescent formation and massive IgA deposition following allogeneic bone marrow transplantation for natural killer cell leukemia/lymphoma

We describe herein a case of nephrotic syndrome (NS) following allogeneic bone marrow transplantation (allo-BMT) for natural killer cell leukemia/lymphoma. Histologic studies defined the diagnosis as crescentic glomerulonephritis with massive immunoglobulin A (IgA) deposition, which has never been reported in NS cases following allo-BMT. Most of the massive infiltrated cells in the interstice were CD3(+)CD4(-)CD8(+) T cells derived from the donor. We observed mesangial deposition of Haemophilus parainfluenza outer membrane (OMHP) antigen and decreased glycosylation of the IgA1 hinge in the recipient's samples is consistent with the recently reported pathogenesis of IgA nephropathy. Further, the titer of IgA antibody against the donor serum was as high as other IgA nephropathy cases. These findings suggest that NS and crescentic glomerulonephritis in this case occurred as one of the forms of chronic graft-versus-host disease (GVHD), and that IgA deposition was associated with H parainfluenza and decreased glycosylation of the IgA1 hinge.

Chronic intestinal graft-versus-host disease: clinical, histological and immunohistochemical analysis of 17 children

Graft-versus-host disease (GVHD) can be acute or chronic. The pathogenesis of chronic GVHD is unclear. Chronic GVHD affects mainly skin, liver and digestive tract. Intestinal involvement is uncommon and histological features are poorly described. We report here the clinical, histological and immunohistochemical features of chronic GVHD with intestinal involvement. Intestinal biopsies from children with chronic GVHD (n=17) were compared to control children (n=21: 10 non-transplant cases, four non-GVHD transplant cases, seven acute GVHD). We evaluated clinical outcome, histological features and characterized immunohistochemically the immune cells involved locally. Chronic GVHD with intestinal involvement was usually multisystemic (88.2%) and preceded by acute GVHD in 88.2% of cases. The outcome was severe with complete recovery in only 58.8% of cases, and death related to chronic GVHD in 17.6% of cases. Histological features were characterized by (1) villous atrophy and (2) glandular lesions, mainly apoptotic with variable intensity and (3) lamina propria infiltrate with cytotoxic T lymphocytes (CD3+, CD8+, TiA1+, granzyme B-) which were significantly (P<0.001) increased compared to non-GVHD transplant and non-transplant controls. Therefore in chronic intestinal GVHD, the apoptotic process could be related to cytotoxic T lymphocytes.

Peripheral blood stem cell allograft rejection mediated by CD4(+) T lymphocytes recognizing a single mismatch at HLA-DP beta 1*0901

Little is known about the molecular characteristics of alloantigens recognized by alloreactive T cells mediating hematologic stem cell graft rejection. In particular, it has never been shown that such alloantigens can be encoded by HLA-DP beta alleles. Indeed, matching for HLA-DP antigens is generally not considered to be of functional importance for the outcome of allogeneic bone marrow or peripheral blood stem cell transplantation. In this study, a case of peripheral blood stem cell allograft rejection was investigated in which the patient and donor differed for a single mismatch at HLA-DP in the rejection direction. Patient-derived T lymphocytes circulating at the time of rejection showed direct ex vivo cytotoxic activity against donor-derived B-lymphoblastoid cells as well as other HLA-DP beta 1*0901--expressing targets. The presence of HLA-DP beta 1*0901--specific effectors in vivo was further confirmed by in vitro stimulation experiments. CD4(+) T-cell lines and clones with specific cytotoxic activity against HLA-DP beta 1*0901--expressing targets including donor B-lymphoblastoid cells were generated both by nonspecific and by donor-specific in vitro stimulation. Taken together, these data demonstrate that HLA-DP can be the target antigen of cytotoxic CD4(+) T lymphocytes involved in peripheral blood stem cell allograft rejection. (Blood. 2001;98:1122-1126)

HLA-DP epitope typing using monoclonal antibodies

We have made a panel of murine anti-DP monoclonal antibodies for serological typing of HLA-DP polymorphisms; they can be used in microcytotoxicity (for 7 epitopes) and binding assays (for 8 epitopes). The antibodies detect polymorphic differences in both alpha and beta chains. As immunogens we sometimes used B-lymphoblastoid lines or purified DP molecules but mostly used mouse fibroblast transfectants expressing DP molecules. The DP beta genes were made from a cloned DPB1*0201 gene by replacing its major area of polymorphism with matching stretches of DNA amplified from other alleles; cloned DPA1*01 and DPA1*02 genes were used for transfection along with the beta chain genes. The monoclonal antibodies showed reaction patterns that correlated with the presence of particular amino-acid sequence motifs; thus none of the antibodies is allele-specific. They bind instead to epitopes which are found on a number of different HLA-DP types. We have constructed frequency tables so that the epitope (motif) data can be interpreted as the most likely genotype in each case. The basic assumption to justify this work is that HLA-DP matching or mismatching will likely influence transplant outcome, particularly in bone marrow transplantation. The present challenge is to define permissive and nonpermissive combinations of HLA-DP; it may be that matching for epitopes, rather than for full alleles, will help to resolve this issue.

Alloresponses to HLA-DP detected in the primary MLR: correlation with a single amino acid difference

The one-way mixed lymphocyte reaction (MLR-1) response was measured in both directions in 50 HLA-A, B, DR and DQ identical pairs and the role of DP studied in MLR stimulation. DR, DQ and DP typing was performed at the allele level by the polymerase chain reaction-sequence specific oligotyping (PCR-SSO) technique. The group consisted of 19 potential bone marrow transplant recipients and 34 matched unrelated donors. When more than one matched donor was available for a patient, donor/donor MLR-1 was also studied. DP identity was observed in 3 out of 50 pairs (6%), however due to homozygosity no incompatibility was present in the stimulating cells in 21 out of 100 cases (21%). There was a significant difference in the range of relative responses (RR) between zero DPB1 mismatches and one (p = 0.002) and two (p = 0.02) DPB1 mismatches: 52.4% of cases in the zero DPB1 mismatch group had RR < 1.0% compared with 31.6% and 27.3% in the one and two DPB1 mismatches. Stimulation by DPB1*0201 and 0301 gave the highest RR (12.9 +/- 22.5 and 17.5 +/- 17.0, respectively) while stimulation with DPB1*0401 and 0402 resulted in low levels of T cell response (1.3 +/- 8.2 and 0.6 +/- 11.5, respectively). When the responses were restricted to DPB1*0401 homozygotes to standardise for responder type similar results were obtained (DPB1*0201 v DPB1*0402 p = 0.008). The protein products of the DPB1*0201 and 0402 alleles differ by a single amino acid at position 69 (DPB1*0402--Lysine, DPB1*0201--glutamic acid). A further analysis was performed therefore scoring responders and stimulators as glutamic acid positive (E+) or negative (E-). There was a highly significant increase in the response to E+ stimulators compared with E- stimulators (p = 0.004). There was also a significant difference in the distribution of relative responses between the E+ stimulator group and the subgroups of E- responders/E- stimulators (p = 0.012) and E+ responders/E- stimulators (p = 0.009). However the amino acid difference at position 69 does not explain all responses due to DP in the MLR-1 as evidenced by the strong responses observed in cases where DPB1*0301 (lysine pos.) was the only difference on the stimulator cells. The results indicate that not all DP incompatibilities elicit a measurable T cell MLR response, but where a response does occur residue 69 in the first domain of DP appears to be pivotal. These results may have implications with respect to GVHD in bone marrow transplantation.

HLA-DPB1 mismatch at position 69 is associated with high helper T lymphocyte precursor frequencies in unrelated bone marrow transplant pairs

HLA incompatibility between bone marrow recipient and unrelated donor pairs is often associated with severe acute graft-versus-host disease following bone marrow transplantation. Due to the extensive polymorphism of HLA genes, finding genotypically identical pairs is a difficult challenge. Therefore, it is crucial to single out the relevance of each HLA gene and, within each sequence, the polymorphic positions that induce a T-cell response. Among HLA class II genes, the relevance of HLA-DPB1 in inducing graft-versus-host disease is still controversial. In this study, we selected 37 bone marrow transplant pairs on the basis of HLA class I A and B identity as determined by isoelectric focusing and of class II identity as determined by serology and by low-resolution genomic typing. We analyzed them for the possible relationship between frequency of cytotoxic T lymphocyte and helper T lymphocyte precursors (CTLp and HTLp, respectively) and genomically determined class II mismatches. Seventeen pairs had high numbers of both CTLp and HTLp. They were not further considered because of the difficulty in determining whether the T-cell response was induced by class I or class II mismatches. Of the remaining pairs with low CTLp and high HTLp, six had disparities at HLA-DRB1 and HLA-DPB1 genes, and 14 differed only at the HLA-DPB1 locus. Among the latter pairs, we found a correlation between HLA-DPB1 mismatches and HTLp frequency, thus suggesting that disparity at this locus influences the alloreactive T-cell response. When the HTLp frequency was correlated with each single mismatch found in the 14 pairs, it appeared that the nature of the amino acid at position beta69 played a relevant role in inducing alloreactivity.

Acute graft versus host disease due to T lymphocytes recognizing a single HLA-DPB1*0501 mismatch

Analysis of a large number of unrelated bone marrow transplantations (BMT) has shown that HLA-DP incompatibility did not detectably influence the risk for acute graft-versus-host disease (aGVHD). Accordingly, it was proposed that HLA-DP determinants did not function as transplantation antigens in the same way as HLA-A, -B, or -DR. We have previously shown that HLA-DP (as well as HLA-A, -B, -DQ, or -DR)-specific T cells could be isolated from skin biopsies of patients who developed an aGVHD after semiallogeneic BMT. Nevertheless, whether a single HLA-DP mismatched allele could induce a detectable allo-specific reaction in vivo after BMT remained to be established. To directly address this issue we studied one patient who presented aGVHD after receiving purified CD34+ bone marrow (BM) cells from an unrelated donor with a single HLA-DP mismatch in the GVHD direction. To characterize the immunological events associated with GVHD, we analyzed the peripheral T cell repertoire, the T cell receptor Vbeta diversity, and the specificity of T cells invading a skin biopsy at the onset of GVHD. Our results demonstrated that a large fraction of skin-infiltrating lymphocytes, which expressed diverse T cell receptors, were reactive against this single HLA-DPB1 *0501 mismatch and consequently that a single HLA-DP mismatch between BM donor and recipient can activate a strong T cell response in vivo.