A human skin explant model for predicting graft-versus-host disease following bone marrow transplantation

Graft-versus-host disease (GVHD) is the most serious complication following bone marrow transplantation, with an incidence of 40-60%. The disease can be fatal in 50% of cases, even in patients receiving marrow from an HLA identical sibling. Several assays have been developed to try to predict the development of GVHD, including mixed lymphocyte culture reaction, cytotoxic T lymphocyte precursor, and helper T lymphocyte precursor frequency assays. This review describes an in vitro skin explant model which has been used since 1988 for both predicting acute GVHD in HLA identical sibling bone marrow transplantation and studying the pathophysiology of the disease. The model involves sensitising donor lymphocytes in vitro in a primary mixed lymphocyte reaction and then evaluating the secondary response on patient skin biopsies by grading the graft-versus-host reactivity (grades I-IV) histopathologically. From analysis of collective data the model is a clear predictor of GVHD and superior to the other assays widely used, with a correlation of 82% with clinical outcome. The skin explant model allows the investigator to study the pathogenesis of GVHD. The cytokines TNF alpha and IFN gamma are shown to be important mediators of cellular damage in graft-versus-host reactions. Recent work has also involved using the model to study the alloreactivity of cord blood. The model is currently being assessed in several bone marrow transplantation centres in Europe on different patient groups including those who receive marrow from haploidentical and matched unrelated donors.

Use of a skin explant model for predicting GVHD in HLA-matched bone marrow transplants - effect of GVHD prophylaxis

Over the last decade we have successfully evaluated the use of a human skin explant assay for predicting acute GVHD in HLA-matched sibling transplants. In the present study, we modified GVHD prophylaxis on an individual patient basis depending on the GVHD outcome predicted by the skin explant model. We have summarised our previous data describing how the skin explant assay results correctly predict GVHD occurrence and severity in 45/56 patients (80%); P< 0.0001, chi2 19.97, df = 1. In a further cohort of 19 patients, all were predicted to develop grade II or above GVHD. These patients were given increased GVHD prophylaxis with the addition of methotrexate and a significant reduction in the expected incidence of GVHD was observed (P = 0.02; chi2 7.7, df = 1; Fisher exact test P = 0.04). The results from these studies suggest that modifying GVHD prophylaxis, based on skin explant assay results, may reduce the expected incidence and severity of GVHD. We suggest that the technique might be used for selective GVHD prophylaxis in T cell non-depleted HLA matched sibling transplants.

Non-Langerhans cell histiocytosis associated with lymphocyte-predominant Hodgkin's disease

We report a 74-year-old man who presented with a rash on the trunk showing clinical and histological features of non-Langerhans cell histiocytosis. Two years after presentation he developed weight loss, lymphadenopathy and hepatosplenomegaly; a diagnosis of lymphocyte-predominant Hodgkin's disease was made on lymph node biopsy. The cutaneous signs and lymphoma responded to chemotherapy. Taken in conjunction with previously published reports of associations between cutaneous histiocytoses and haematological malignancies, we recommend close observation of patients in whom a diagnosis of non-Langerhans cell histiocytosis is made.

Predicting graft-versus-host disease in HLA-identical bone marrow transplant: a comparison of T-cell frequency analysis and a human skin explant model

BACKGROUND

Graft-versus-host disease (GVHD) occurring after HLA-identical sibling bone marrow transplantation (BMT) is considered to be mainly caused by minor histocompatibility antigen (mHag) disparities between the recipient and donor. In our laboratory, a human skin explant model has been successfully used to predict acute GVHD in HLA-identical sibling BMT. More recently, the frequency analysis of host-reactive helper and cytotoxic T lymphocyte precursors (HTLp and CTLp, respectively) has been shown to have potential application for predicting GVHD. In the present study, HTLp and CTLp frequency analysis and the skin explant model were directly compared for their ability to predict acute GVHD in HLA-identical sibling BMT.

METHODS

Host-reactive HTLp and CTLp frequencies were determined using a combined limiting dilution assay. A human skin explant model was used to detect graft-versus-host reactions in vitro. The results from the skin explant model (graft-versus-host reaction grades I-IV) and T cell frequency analysis (>/< 1:100,000) were correlated with posttransplant GVHD outcome, respectively.

RESULTS

The skin explant model correctly predicted GVHD outcome in 77% of cases (P=0.03). HTLp frequencies were very low in all patient/donor pairs tested. None of them exceeded 1:100,000, although 9/18 recipients developed GVHD (> or =clinical grade II) after transplant. In all patients tested, the relationship between either high (>1:100,000) or low (<1:100,000) CTLp frequency and occurrence of GVHD appeared to be random (P=1.0).

CONCLUSIONS

HTLp and CTLp frequency analysis did not predict the occurrence of acute GVHD after HLA-identical sibling BMT. The human skin explant model, however, remained an accurate indicator of acute GVHD and probably detects mHag disparities.

Cellular alloreactivity of human cord blood cells detected by T-cell frequency analysis and a human skin explant model

BACKGROUND

Recent clinical data have demonstrated the success of allogeneic stem cell transplantation using HLA-mismatched unrelated human umbilical cord blood (CB). The incidence and severity of acute graft-versus-host disease (GVHD) in these mainly pediatric transplants is low. The immunological mechanisms by which CB transplants may result in reduced GVHD is not completely clear. In this study, the functional cellular alloreactivity of CB cells was investigated, by measuring the frequency of alloreactive helper and cytotoxic T lymphocyte precursors (HTLp and CTLp, respectively) in CB and detecting the ability of CB cells to induce graft-versus-host (GVH) type alloreactivity in vitro.

METHODS

A human skin explant model was used to measure GVH type alloreactivity in vitro. A combined limiting dilution assay was carried out in parallel to determine alloreactive HTLp and CTLp frequencies. The cellular alloreactivity was compared between cord and HLA-haploidentical parental blood cells against the same HLA-mismatched unrelated stimulator.

RESULTS

The results demonstrated that alloreactive CTLp frequency in CB mononuclear cells (CBMCs) was significantly lower (mean, 1:35,694, range, 1:1,667-<1:500,000) than that in adult peripheral blood mononuclear cells (PBMCs) (mean, 1:5,333, range, 1:544-1:47,619). Alloreactive HTLp frequencies, however, were comparable for CBMCs and PBMCs (mean, 1:7,586, range, 1:1,359-1:200,000; and mean, 1:5,976, range, 1:385-1:50,000, respectively). A significantly decreased ability to induce in vitro GVH type alloreactivity was observed for CBMCs and that was strongly associated with low alloreactive CTLp frequencies (P=0.001).

CONCLUSIONS

The present study provides the first clear in vitro evidence to suggest that CBMCs are less able than PBMCs to induce skin GVH type alloreactivity in HLA-mismatched pairs. The severity of in vitro GVH type alloreactivity (graded as I-IV) was strongly associated with the levels of alloreactive CTLp frequencies. The low cellular alloreactivity of CBMCs detected in vitro suggests that in a proportion of cases HLA-mismatched unrelated CB may not give rise to severe GVHD in vivo after transplantation.

Mononuclear phagocyte populations in the transplanted human lung

BACKGROUND

Dendritic cells (DC) are essential for the development of alloreactivity, however, little has been published regarding the distribution and phenotype of these and related mononuclear cells in human lung transplantation.

METHODS

Lung frozen sections were examined for the presence of CD1a+ DC and for mononuclear cells and alveolar macrophages expressing CD11b and CD68. The effects of transplantation and immunosuppression were assessed by comparison of normal transplant transbronchial biopsy specimens to specimens from unused donor lungs; the normal transbronchial biopsy specimens also were compared with those showing rejection or obliterative bronchiolitis.

RESULTS

All biopsy specimens, including those with obliterative bronchiolitis, showed a marked depletion of CD1a+ DC in lung allografts. This has not been described previously. In addition, transplantation and immunosuppression reduced alveolar macrophage coexpression of CD68 and CD11b, and this was reversed in acute rejection.

CONCLUSION

The roles of pulmonary DC and other mononuclear phagocyte subpopulations need to be further defined, and data from animal models of lung transplantation should be interpreted with caution.

Acute infiltration by non-Hodgkin's B-cell lymphoma of lesions of disseminated herpes zoster

A man with a 15-year history of non-Hodgkin's lymphoma presented with disseminated herpes zoster which initially responded to aciclovir. This was shortly followed by an acute exacerbation in the sites previously affected which was apparently resistant to antiviral therapy. Biopsy revealed a dense monomorphic lymphocytic infiltrate below active herpes zoster which had the same morphology and immunoreactivity as the underlying lymphoma. His clinical condition resolved with further chemotherapy for his lymphoma and continued treatment with aciclovir.

Mohs' surgery of periocular basal cell carcinoma using formalin-fixed sections and delayed closure

Mohs' surgery of periocular basal cell carcinoma (BCC) ensures a high cure rate with maximal preservation of normal tissue. The formalin-fixed paraffin-embedded tissue technique allows Mohs' surgery to be performed using routine pathology facilities and permits the efficient use of operating room personnel and theatre time. The inevitable delay between excision and closure may potentially result in a poor functional and cosmetic outcome, particularly around the eye. We prospectively studied all patients with periocular BCC treated with this technique at our unit between 1985 and 1996. One hundred and twenty-three periocular BCCs in 120 patients were treated. Microscopic clearance was achieved in all cases. Closure was performed on average 5 days after the initial excisional stage. Closing procedures included direct closure, flaps and grafts. Significant complications affecting outcome were noted in only two patients. Eighty-eight per cent of patients assessed had a functional and cosmetic result regarded as excellent, good or adequate. Mohs' surgery of periocular BCC using formalin-fixed paraffin-embedded tissue and delayed closure results in a satisfactory functional and cosmetic outcome and offers a viable alternative to the frozen section fresh tissue technique.

Angiosarcoma arising in a chronically lymphoedematous leg

Cutaneous angiosarcoma is a rare aggressive tumour of capillary and lymphatic endothelial cell origin. It presents as multiple purple and red papules and nodules on the head and neck or the extremities. We report an 86-year-old woman with angiosarcoma arising on her chronically lymphoedematous right leg. The lymphoedema, secondary to chronic immobility, had developed gradually over 40 years. No other family members had lymphoedema. The patient presented with a plaque of friable tumour tissue on the lower right leg and dorsum of the foot, and satellite lesions on the knee and groin which initially appeared to be petechial haemorrhages. The satellite lesions in the groin grew into tumour nodules. There was no evidence of a preceding malignancy, nor any operative intervention to the affected limb or abdomen. Histological examination of all tumour specimens revealed moderately to poorly differentiated angiosarcoma. She died within 5 months of the first appearance of the skin nodules.

An indolent penile herpetic ulcer in a patient with previously undiagnosed human immunodeficiency virus infection

We report a case of an atypical penile herpetic ulcer in a man with previously undiagnosed human immunodeficiency virus (HIV) infection. Swabs of the lesion were negative for herpes simplex virus (HSV) by culture and electron microscopy. However, histopathology of biopsy material showed characteristic herpetic multinucleate giant cells. Immunochemistry using polyclonal antibodies was positive for HSV1 and HSV2. The lesion completely resolved after treatment with aciclovir and the patient subsequently tested positively for HIV antibodies.

Vesicular mycosis fungoides

Blistering is not a feature normally associated with mycosis fungoides (MF). We present a case of MF in which histopathological vesicle formation was such a prominent feature that diagnosis was delayed. The patient's disease ran an aggressive course and death occurred within one year of presentation. Tumour involvement of the tongue with MF was an unusual late feature.

Quantification of regional matrix nail production

The relative nail producing capacity of different regions within the nail matrix has not been quantified. In order to do this, the number of nail plate cells in the dorsoventral axis of 12 human great toenails was counted at five sites in the longitudinal axis, and compared with direct measurements of nail plate thickness at the same sites. The mean number of nail cells in the nail plate reached a maximum at the lunula, with no further increase along the length of the nail bed. At the mid-point between the proximal tip of the germinal matrix and lunula, mean cell numbers achieved 81% of the value at the lunula. Mean nail thickness was only 90% of its maximum at the lunula, with a further significant increase (P = 0.02) between the lunula and end of the nail bed. These observations suggest that the proximal nail matrix is the main source of nail within the matrix. This is consistent with clinical experience where distal matrix surgery has a low potential for scarring in comparison with proximal matrix surgery. The additional finding of increased nail thickness, but not cell numbers, along the nail bed make it likely that cells within the nail plate change shape as they move distally.

Spontaneous regression in angiocentric T-cell lymphoma

An 8-year-old boy presented with a 10-week history of ulcerating lesions which were histologically and immunocytochemically consistent with the diagnosis of angiocentric T-cell lymphoma. The disease was limited to the skin and resolved with no chemotherapy. Angiocentric T-cell lymphoma is commonly a disease with considerable morbidity and is often fatal. Epstein-Barr virus (EBV) could not be identified in involved tissue by immunostaining or by in situ hybridization. We consider whether the uncharacteristic absence of EBV in this case has prognostic significance.

Human herpes virus-6 infection in marrow graft recipients: role in pathogenesis of graft-versus-host disease. Newcastle upon Tyne Bone Marrow Transport Group

To investigate the hypothesis that target organ infection with human herpes virus-6 (HHV-6) exacerbates the clinical severity of GVHD, skin and rectal biopsies from 34 allogeneic bone marrow transplant (BMT) recipients and 23 comparative autologous recipients were studied. Biopsies and heparinised blood samples were obtained from all patients prior to and at regular intervals after BMT, and whenever GVHD was suspected. HHV-6 antigen was detected in cryostat sections by immunohistochemistry, and HHV-6 DNA in peripheral blood leucocytes (PBL) and biopsies by nested PCR. Twenty-eight (90%) of the 31 patients who engrafted developed clinical GVHD, which was mild in five, moderately severe in nine and severe in 14. Overall, HHV-6 DNA was detected in PBl in 74% of autologous recipients and 76% of allogeneic recipients, and in biopsy tissue in 48% of autos and 71% of allos. However, HHV-6 DNA was detected in skin and/or rectal biopsies more frequently in allogeneic recipients with severe GVHD (92%) than in those with either moderate (55%) or mild GVHD (22%), suggesting an association (P = 0.004) between HHV-6 DNA in biopsy tissue and GVHD severity. A significant linear trend (P = 0.03) was identified between detection of HHV-6 DNA in biopsy tissue obtained prior to or concomitant with the onset of GVHD and increased GVHD severity, suggesting that HHV-6 was causally linked to GVHD rather than reactivated as a consequence of GVHD therapy. Thus this study supports a role for HHV-6 in the initiation and/or exacerbation of GVHD, and suggests that the presence of HHV-6 DNA in the skin or rectum may be a factor in determining GVHD severity. If confirmed, these findings may have implications for the management of allogeneic BMT recipients.

Synovial chondromatosis presenting as painless soft tissue mass--a report of 19 cases

Primary synovial chondromatosis is a disorder of joints, tendon sheaths and bursae characterized by the formation and growth of cartilaginous nodules. It usually presents clinically with joint symptoms and is frequently associated with intra-articular loose bodies. A large soft tissue mass is an unusual presentation which, both clinically and radiologically, raises the suspicion of malignancy. Nineteen cases of synovial chondromatosis presenting as soft tissue tumours were reviewed. They were all adjacent to joints but with no joint symptoms. Histology showed the typical features of benign synovial chondromatosis, including foci of cartilage cells showing cytological atypia. This is well recognized and does not indicate malignancy. Clinical follow up confirmed this with local recurrence only in three patients. It is important to be aware of this unusual presentation as the alternative diagnosis of a chondrosarcoma, as initially diagnosed in some of these cases, has major implications regarding the treatment of these patients.

Role of target organ infection with cytomegalovirus in the pathogenesis of graft-versus-host disease

Skin and rectal biopsy tissue from 34 allogeneic and 23 autologous BMT recipients was prospectively analysed for CMV using immunohistochemistry and PCR to investigate the hypothesis that target organ infection with CMV initiates and/or exacerbates GVHD. Biopsies were obtained prior to and at 3, 8 and 26 weeks after BMT and whenever GVHD was suspected. Surveillance specimens of peripheral blood leucocytes (PBL), urine and throat swabs were obtained every 2 weeks until 12 weeks after BMT, and whenever CMV was suspected. Cryostat sections were analysed immunohistochemically for CMV antigens and PBL and biopsies for CMV DNA by PCR. Of the 31 patients who engrafted, 28 (90%) developed GVHD clinically, confirmed histologically in 56 biopsies. GVHD proved clinically severe in 14 patients, 4 of whom had treatment-resistant GVHD. CMV was detected in PBL more frequently in patients with severe GVHD than in those with mild/moderate GVHD (29% vs. 7%). However, in all but one patient the onset of GVHD preceded detection of CMV. In biopsy specimens, CMV was detected in only 2 patients, 1 of whom had an exacerbation of GVHD temporally associated with CMV. Thus, despite a high incidence of GVHD in this series, with 56 episodes of GVHD in 28 patients, only 1 patient had CMV in biopsy tissue temporally associated with GVHD. This suggests that biopsy infection with CMV is not a major factor in initiating or exacerbating GVHD in this cohort. This study thus does not support a role for target organ infection with CMV in the pathogenesis of GVHD.

MHC class II and ICAM-1 expression and lymphocyte subsets in transbronchial biopsies from lung transplant recipients

The expression of MHC class II antigens and ICAM-1 and the composition of lymphocyte infiltrates have been studied in frozen sections of transbronchial biopsies from lung transplant recipients. First, biopsies obtained from patients who showed acute rejection, OB, and normal features were compared. Second, we compared first-year biopsies from patients developing OB and patients with a good clinical outcome. HLA-DR was widely expressed on epithelia and vascular endothelium. Increased vascular HLA-DP expression was found in OB biopsies. In OB patients there was a significantly increased frequency of bronchial HLA-DP and vascular HLA-DQ expression. Expression of ICAM-1 by bronchial and bronchiolar basal cells, a phenomenon not reported previously in humans, was seen in a small number of biopsies. CD8 predominant lymphocytic infiltrates were present in all groups and were increased in OB biopsies and OB patients. Increased numbers of CD4-positive cells were found in rejection and OB when compared with normal biopsies. These findings support an immunological basis for the development of OB.

Organizing pneumonia following pulmonary transplantation and the development of obliterative bronchiolitis

Twelve patients receiving lung transplants between 1988 and 1992 who developed clinical and histological features of obliterative bronchiolitis (OB) were compared with a group of 13 patients with good stable lung function (FEV1 more than 80% of predicted). Histological features of 180 biopsies were studied from the first postoperative year in order to assess whether any were associated with the development of OB. Clinically and histologically defined pulmonary rejection occurring after the first month was more frequent in OB patients (P = 0.03). Organizing pneumonia that was associated with acute rejection but not with nonviral infection was also seen more frequently in OB patients (P = 0.003). When all available lung transplant recipients surviving beyond 18 months were included in analyses, organizing pneumonia in the first year was associated with an increased relative risk of developing OB of 2.26 (95% CL 1.19-4.29), and the occurrence of coexistent organizing pneumonia and pulmonary rejection gave a relative risk for OB of 6.33 (95% CL 1.61-24.94). An increased incidence of histologically defined organizing pneumonia in OB patients has not been described previously. Furthermore the coexistence of organizing pneumonia with pulmonary rejection in the first year posttransplantation is a strong predictive factor for the development of OB.

Diagnostic features of transfusion associated graft versus host disease

AIMS

To define the immunopathological profile of transfusion associated graft versus host disease (TA-GvHD) to elucidate its pathophysiology and to determine if any features are of diagnostic value.

METHODS

Nine patients (age range 14-61 years) who developed histologically confirmed TA-GvHD between 1989 and 1992 were studied. Immunohistochemical analysis of frozen and formalin fixed skin biopsy tissue was performed. Sections were stained with antibodies to CD3, CD8, CD4 and HLA-DR, using a routine streptavidin-biotin technique with standard diaminobenzidine development.

RESULTS

All biopsy specimens showed aberrant positive expression of HLA-DR by epidermal keratinocytes. In four patients, all of whom died, HLA-DR was diffusely expressed throughout the epidermis; in the other five cases keratinocyte expression of HLA-DR was more focal. In all biopsy specimens T cells had infiltrated the dermis and epidermis. In all nine cases CD4+ T helper/inducer cells were the predominant T cells.

DISCUSSION

Immunohistochemical studies are of value in the diagnosis of TA-GvHD. Aberrant keratinocyte expression of HLA-DR and dermal and epidermal infiltration of CD4+ T cells are immunopathological features of TA-GvHD. Immunohistochemical analysis of skin biopsy tissue using antibodies to these markers is thus a useful investigation in pancytopenic patients presenting with unexplained rashes.

Late development of graft-versus-host disease in an autologous BMT recipient

Clinical and histological changes consistent with GVHD have been described in recipients of both syngeneic and autologous grafts. The mechanism of autologous GVHD is well documented. However, cases of autologous GVHD previously reported have all occurred within the first 2 months post-BMT. We report the case of an autologous BMT recipient in whom histological features consistent with GVHD emerged 7 months post-BMT, which may have implications for the long-term follow-up of autologous marrow graft recipients.