Immunohistochemical analysis of T cell phenotypes in patients with graft-versus-host disease following allogeneic bone marrow transplantation

T-cell depleted haploidentical hematopoietic cell transplantation for pediatric malignancy

Access to allogenic hematopoietic cell transplantation (HCT), a potentially curative treatment for chemotherapy-resistant hematologic malignancies, can be limited if no human leukocyte antigen (HLA) identical related or unrelated donor is available. Alternative donors include Cord Blood as well as HLA-mismatched unrelated or related donors. If the goal is to minimize the number of HLA disparities, partially matched unrelated donors are more likely to share 8 or 9 of 10 HLA alleles with the recipient. However, over the last decade, there has been success with haploidentical HCT performed using the stem cells from HLA half-matched related donors. As the majority of patients have at least one eligible and motivated haploidentical donor, recruitment of haploidentical related donors is frequently more rapid than of unrelated donors. This advantage in the accessibility has historically been offset by the increased risks of graft rejection, graft-versus-host disease and delayed immune reconstitution. Various ex vivo T-cell depletion (TCD) methods have been investigated to overcome the immunological barrier and facilitate immune reconstitution after a haploidentical HCT. This review summarizes historical and contemporary clinical trials of haploidentical TCD-HCT, mainly in pediatric malignancy, and describes the evolution of these approaches with a focus on serial improvements in the kinetics of immune reconstitution. Methods of TCD discussed include in vivo as well as ex vivo positive and negative selection. In addition, haploidentical TCD as a platform for post-HCT cellular therapies is discussed. The present review highlights that, as a result of the remarkable progress over half a century, haploidentical TCD-HCT can now be considered as a preferred alternative donor option for children with hematological malignancy in need of allogeneic HCT.

Enhanced Immune Reconstitution of γδ T Cells after Allogeneic Stem Cell Transplantation Overcomes the Negative Impact of Pretransplantation Minimal Residual Disease-Positive Status in Patients with Acute Myelogenous Leukemia

Minimal/measurable residual disease (MRD) before allogeneic stem cell transplantation (allo-SCT) in patients with acute myelogenous leukemia (AML) is a poor risk factor for outcome. γδ T cells represent a unique minority lymphocyte population that is preferentially located in peripheral tissues, can recognize antigens in a non-MHC-restricted manner, and plays a "bridging" role between the innate and adaptive immune systems. In this study, we investigated a potential graft-versus-leukemia effect of γδ T cell reconstitution post-transplantation in AML patients with pretransplantation positive MRD status (MRD⁺). MRD assessment was performed in 202 patients using multicolored flow cytometry ("different from normal" strategy); 100 patients were deemed MRD⁺. Analysis for absolute concentrations of CD3⁺, CD4+, CD8⁺, natural killer, and γδ T cells were performed by flow cytometry according to an internal protocol at day +30 and +100 post-transplantation. Differences between categorical and continuous variables were determined using the chi-square and Student t test, respectively. The Mann-Whitney U test was used to compare medians of continuous variables. Spearman's correlation was used for nonparametric assessment of correlation between different cell subsets during immune reconstitution. Kaplan-Meier survival analysis and Cox regression analysis were used to investigate the associations between immune reconstitution and survival outcomes. Gray's analysis was used to compute incidences of relapse, nonrelapse mortality, and graft-versus-host disease (GVHD). The median follow-up of survivors was 28 months (range 3 to 59 months). Younger age (≤58 years) of recipient and donor (<30 years), sex mismatch, use of a matched donor, cytomegalovirus reactivation, and administration of antithymocyte globulin were associated with a faster γδ T cell reconstitution. In multivariable analysis for MRD⁺ patients, a higher than median level of γδ T cells on days +30 and +100 resulted in significantly improved leukemia-free survival (hazard ratio [HR], 0.42 [P = .007] and 0.42 [P = .011], respectively) and overall survival (HR, 0.44 [P = .038] and 0.33 [P = .009], respectively). Furthermore, a higher γδ T cell level on day +30 was associated with a significantly reduced risk of relapse (HR, 0.36; P = .019). No impact of γδ T cell level on relapse at days +30 and +100 could be seen in MRD-negative patients, and no correlation with occurrence of GVHD was observed. Our data indicate that enhanced immune reconstitution of γδ T cells post-transplantation may overcome the higher relapse risk of pretransplantation MRD⁺ status in patients with AML.

Impact of γδ T cells on clinical outcome of hematopoietic stem cell transplantation: systematic review and meta-analysis

Allogeneic hematopoietic stem cell transplantation (HSCT) using αβ T-/B-cell-depleted grafts recently emerged as a transplant strategy and highlighted the potential role of γδ T cells on HSCT outcomes. Our aim was to scrutinize available evidence of γδ T-cell impact on relapse, infections, survival, and acute graft-versus-host disease (aGVHD). We performed a systematic review and meta-analysis of studies assessing γδ T cells in HSCT. We searched PubMed, Web of Science, Scopus, and conference abstracts from inception to March 2019 for relevant studies. We included all studies that assessed γδ T cells associated with HSCT. Data were extracted independently by 2 investigators based on strict selection criteria. A random-effects model was used to pool outcomes across studies. Primary outcome was disease relapse. We also assessed infections, survival, and aGVHD incidence. The review was registered with PROSPERO (CRD42019133344). Our search returned 2412 studies, of which 11 (919 patients) were eligible for meta-analysis. Median follow-up was 30 months (interquartile range, 22-32). High γδ T-cell values after HSCT were associated with less disease relapse (risk ratio [RR], 0.58; 95% confidence interval [95% CI], 0.40-0.84; P = .004; I2 = 0%), fewer viral infections (RR, 0.59; 95% CI, 0.43-0.82; P = .002; I2 = 0%) and higher overall (HR, 0.28; 95% CI, 0.18-0.44; P < .00001; I2 = 0%) and disease-free survivals (HR 0.29; 95% CI, 0.18-0.48; P < .00001; I2 = 0%). We found no association between high γδ T-cell values and aGVHD incidence (RR, 0.72; 95% CI, 0.41-1.27; P = .26; I2 = 0%). In conclusion, high γδ T cells after HSCT is associated with a favorable clinical outcome but not with aGVHD development, suggesting that γδ T cells have a significant effect on the success of HSCT. This study was registered with PROSPERO as #CRD42019133344.

Allogeneic Stem Cell Transplantation with CD34+ Cell Selection

The success of allogeneic stem cell transplant is hampered by the development of acute and chronic graft-versus-host disease (GvHD) which has direct impact on treatment-related mortality and morbidity. As a result, T cell depletion through positive selection of CD34+ cells has emerged as a promising strategy to reduce acute and chronic GvHD in these patients.

In this review, we summarize the main characteristics of allogeneic stem cell transplant with CD34+ cell selection including risks of graft failure, GvHD, infection, organ toxicity, and long-term survival. Moreover, we highlight future strategies to improve the results of this platform and to consolidate its use in clinical practice.

Expanding Therapeutic Opportunities for Hematopoietic Stem Cell Transplantation: T Cell Depletion as a Model for the Targeted Allograft

Allogeneic hematopoietic cell transplantation is a fundamental part of the treatment of hematologic malignancies and marrow failure syndromes, but complications including graft-versus-host disease, prolonged immune deficiency and infection, and organ toxicities, as well as relapse, remain obstacles to improved overall survival. As the cellular characteristics of the allograft can exert significant impact on outcomes, the development of more strategically designed grafts represents a rich area for therapeutic intervention. We describe the use of ex vivo T cell–depleted grafts as a model for the targeted graft and review evolving knowledge and approaches for further refinement of allografts to improve patient outcomes.

Effect of granulocyte colony-stimulating factor mobilization on the expression patterns, clonality and signal transduction of TRAV and TRBV repertoire

The immune modulatory effect of granulocyte colony-stimulating factor (G-CSF) on T cells resulted in an unexpected low incidence of graft-versus-host disease (GVHD) in allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Recently, αβ(+) T cells are identified as the primary effector cells for GVHD. However, whether G-CSF could influence the repertoire of αβ(+) T cells (TRAV and TRBV repertoire) and CD3 genes remains unclear. To further characterize this feature, we investigated the effect of G-CSF mobilization on the T cell receptors (TCR) of αβ(+) T cells (TRAV and TRBV repertoire) and CD3 genes, as well as the association between the changes of TCR repertoire and GVHD in patients undergoing G-CSF mobilized allo-PBSCT. We found that G-CSF mobilization had an effect on the expression patterns, clonality and signal transduction of TRAV and TRBV repertoire. This alteration might play a role in mediating GVHD in G-CSF mobilized allo-PBSCT.

Alefacept in corticosteroid refractory graft versus host disease: Early results indicate promising activity

Steroid refractory graft versus host disease (GVHD) presents a significant therapeutic challenge due to the limited efficacy and safety of second-line treatments. Three patients with extensively pretreated, refractory GVHD were treated with a targeted anti-T-cell agent, alefacept, and demonstrated rapid and clinically significant improvement in their GVHD, facilitating tapering of corticosteroids. The pathological and immunohistochemical findings of GVHD also improved, validating our clinical impression. These preliminary findings indicate that alefacept may have beneficial activity in GVHD warranting further study.

Histological and immunohistochemical characterisation of conjunctival graft vs host disease following haematopoietic stem cell transplantation

BACKGROUND

Conjunctival graft vs host disease (cnGvHD) is a complication of haematopoietic stem cell transplantation, in most cases as part of systemic GvHD. Diagnostic biopsies are commonly collected from bulbar conjunctiva only. The aims of our study were to evaluate whether additional biopsies from the tarsal conjunctiva increase sensitivity upon histopathologic evaluation and to investigate the staining profile for common immunohistochemical markers in cnGvHD. We additionally propose an adaptive histological classification for cnGvHD analogous to Lerner's GvHD skin classification for predicting patient survival.

METHODS

Formalin-fixed and paraffin-embedded conjunctival specimens from 23 post-mortem control eyes and 42 patients after haematopoietic stem cell transplantation (HSCT) were stained with haematoxylin and eosin (HE), periodic acid-Schiff (PAS) stain and with antibodies against CD1a, CD4, CD8, CD25, CD45RO, CD68, Fas ligand, TIA-1, HLA-DRalpha by means of immunohistochemistry. Cell counting took place in ten representative fields at 64.4 microm (length) x 21.2 microm (width). Multifactorial analysis of variance was performed to assess any influence of cnGvHD on the staining pattern for the immunohistochemical markers. Survival times were estimated by the Kaplan-Meier method.

RESULTS

All 42 specimens and none of the controls were diagnosed as cnGvHD. The bulbar specimens were staged according to the modified Lerner classification: grade (G) I: 0; G II: 17 (tarsal with G<or=II, 2; G>II, 8); G III: 12 (tarsal with G<or=III: 2; G>III: 1); G IV: 12 (tarsal with G<or=IV: 6); G V: 1. The number of pairs with either the tarsal or bulbar counterpart being more severely affected was almost equal (10 vs 9). A tendency towards shorter survival in advanced bulbar cnGvHD was demonstrated (G III-V vs G I-II, p =0.06). Staining for the immunohistochemical markers in cnGvHD differed significantly from that in controls (p<0.01). Proposed markers for cnGvHD (e = epithelium, s = stroma; mean cell counts +/- SD; cnGvHD vs controls) are: CD8 s (15.7 +/- 18.4 vs 6 +/- 5.6), CD25 s (2.6 +/- 2.8 vs 0.7 +/- 1.6), CD68 s (8 +/- 9 vs 3.9 +/- 3.5) at the bulbar site and CD1a e (1.2 +/- 1.6 vs 0.3 +/- 0.6) and TIA-1 e (2.2 +/- 2.2 vs 1.1 +/- 1.3) at the tarsal site.

CONCLUSIONS

Additional tarsal biopsy does not seem to add relevant diagnostic sensitivity for cnGvHD when the modified Lerner classification is applied. The modified Lerner classification of the bulbar cnGvHD seems to be of prognostic value.

Host-reactive CD8+ memory stem cells in graft-versus-host disease

Graft-versus-host disease (GVHD) is caused by alloreactive donor T cells that trigger host tissue injury. GVHD develops over weeks or months, but how this immune response is maintained over time is unknown. In mouse models of human GVHD, we identify a new subset of postmitotic CD44(lo)CD62L(hi)CD8(+) T cells that generate and sustain all allogeneic T-cell subsets in GVHD reactions, including central memory, effector memory and effector CD8(+) T cells, while self-renewing. These cells express Sca-1, CD122 and Bcl-2, and induce GVHD upon transfer into secondary recipients. The postmitotic CD44(lo)CD62L(hi)CD8(+) T cells persist throughout the course of GVHD, are generated in the initial phase in response to alloantigens and dendritic cells and require interleukin-15. Thus, their long life, ability to self-renew and multipotentiality define these cells as candidate memory stem cells. Memory stem cells will be important targets for understanding and influencing diverse chronic immune reactions, including GVHD.

Alloreactive memory T cells are responsible for the persistence of graft-versus-host disease

Graft-vs-host disease (GVHD) is caused by a donor T cell anti-host reaction that evolves over several weeks to months, suggesting a requirement for persistent alloreactive T cells. Using the C3H.SW anti-C57BL/6 (B6) mouse model of human GVHD directed against minor histocompatibility Ags, we found that donor CD8(+) T cells secreting high levels of IFN-gamma in GVHD B6 mice receiving C3H.SW naive CD8(+) T cells peaked by day 14, declined by day 28 after transplantation, and persisted thereafter, corresponding to the kinetics of a memory T cell response. Donor CD8(+) T cells recovered on day 42 after allogeneic bone marrow transplantation expressed the phenotype of CD44(high)CD122(high)CD25(low), were able to homeostatically survive in response to IL-2, IL-7, and IL-15 and rapidly proliferated upon restimulation with host dendritic cells. Both allogeneic effector memory (CD44(high)CD62L(low)) and central memory (CD44(high)CD62L(high)) CD8(+) T cells were identified in B6 mice with ongoing GVHD, with effector memory CD8(+) T cells as the dominant (>80%) population. Administration of these allogeneic memory CD8(+) T cells into secondary B6 recipients caused virulent GVHD. A similar allogeneic memory CD4(+) T cell population with the ability to mediate persistent GVHD was also identified in BALB/b mice receiving minor histocompatibility Ag-mismatched B6 T cell-replete bone marrow transplantation. These results indicate that allogeneic memory T cells are generated in vivo during GVH reactions and are able to cause GVHD, resulting in persistent host tissue injury. Thus, in vivo blockade of both alloreactive effector and memory T cell-mediated host tissue injury may prove to be valuable for GVHD prevention and treatment.

Skin biopsies for early diagnosis and prognosis of graft-versus-host disease in recipients of allogeneic stem cells from blood or bone marrow

A total of 61 patients with haematological malignancies were randomised either to allogeneic transplantation with blood stem cells (BSC) or bone marrow (BM), of whom 37 patients gave their consent to participate in a skin biopsy trial. Skin biopsies were performed before and after transplantation. The main objective was to assess whether biopsies of normal and affected skin from patients allografted with BSC showed a different histopathological and immunohistochemical pattern as compared to biopsies taken from patients allografted with BM. In addition, we wished to clarify whether sequential skin biopsies could be of prognostic value with regard to graft-versus-host disease (GVHD). Biopsies from normal or affected skin in BSC allografted did not disclose a different pattern as compared to BM transplants. Biopsies taken before the outbreak of acute and chronic GVHD showed no substantial differences between the groups. Irrespective of the type of allograft, the immunohistochemical picture of affected skin consistent with acute GVHD was dominated by a significantly higher number of T-lymphocytes (CD8+). Biopsies from normal skin before the outbreak of GVHD had no predictive value with regard to the development of acute or chronic GVHD. Immunohistochemistry is of supplementary help in distinguishing changes caused by cytotoxic agents from those caused by acute GVHD.

In vitro adherence of lymphocytes to dermal endothelium under shear stress: implications in pathobiology and steroid therapy of acute cutaneous GVHD

The extravasation of leukocytes at sites of inflammation critically depends on initial shear-resistant adhesive interactions between leukocytes in blood flow and target tissue endothelium. Dermal lymphocytic infiltrates are a hallmark feature of acute cutaneous graft-versus-host disease (acGVHD) following allogeneic hematopoietic stem cell (allo-HSC) transplantation. These infiltrates occur commonly during periods of profound lymphopenia, suggesting that the dermal endothelial adhesive mechanism(s) promoting lymphocyte emigration in acGVHD are highly efficient. To examine this issue, we performed Stamper-Woodruff assays on frozen sections of biopsy specimens of cutaneous lesions occurring within 100 days of HSC transplantation in 22 autologous hematopoietic stem cell transplant (auto-HSCT) and 25 allo-HSCT recipients. By using this shear-based assay, we observed lymphocyte adherence to papillary dermal vascular structures in all punch biopsy specimens of allo-HSCT recipients who had clinicohistologic evidence of acGVHD and who were not receiving steroids, whereas no lymphocyte adherence was observed within skin specimens from allo-HSCT recipients who did not develop acGVHD. Within the group of auto-HSCT recipients, 2 of 22 skin biopsies demonstrated lymphocyte binding to dermal vessels. Among allo-HSCT patients receiving steroid therapy for acGVHD, lymphocyte binding to dermal endothelium was abrogated prior to resolution of rash in those who responded, yet binding was persistent in skin from one patient whose rash did not respond to steroid therapy. Collectively, these data indicate that the papillary endothelium of skin in acGVHD displays heightened capacity to support lymphocyte adhesion under shear stress conditions and suggest that down-modulation of this endothelial adhesive capability may be one mechanism by which steroids abrogate acGVHD reactions.

Chronic graft-versus-host disease manifesting as polymyositis: an uncommon presentation

Graft-versus-host disease (GVHD) remains a major complication of allogeneic hematopoietic stem cell transplantation. Polymyositis can occur in association with chronic GVHD and mimics the idiopathic form of the disease. We report two cases of chronic GVHD-associated polymyositis and review the published literature. The two patients presented 13 and 19 months after allogeneic transplantation with characteristic features of muscular hypotrophy, proximal muscle weakness, pain, elevated creatine phosphokinase (CPK), aldolase and SGPT. Interestingly, both patients had HLA DR52 genes, which is frequently reported in association with idiopathic polymyositis. Electromyogram (EMG) and muscle biopsy confirmed the diagnosis. Treatment with cyclosporine or tacrolimus resulted in complete and sustained remission of polymyositis in both cases. A review of the literature shows cyclosporine and steroids are well-described treatment options for patients with myositis in post transplant, as well as idiopathic cases. The duration of immunosuppressive treatment has varied in different reports, and there is a risk of recurrence when immunosuppression is tapered.

Reconstitution of the CD45RO(+) and CD20(+) lymphoid marrow population following allogeneic bone marrow transplantation for Ph(+) CML

Following bone marrow transplantation (BMT) investigations on the recovery of the B and T lymphocyte populations have focused on the peripheral blood and only marginally regard the bone marrow. An immunohistochemical and morphometric study was performed on 352 trephine biopsies derived from 123 patients with chronic myelogenous leukemia (CML) at standardized endpoints before and after allogeneic BMT and compared to a control group. The purpose of this investigation was to quantify the B-CD20(+) and T-CD45RO(+) lymphocyte subsets and to determine possible relationships with the occurrence of acute and chronic GVHD. Moreover, we studied the dynamics of lymphocyte repopulation in the post-transplant period, correlations with the total peripheral lymphocyte count and differences associated with sibling vs alternate HLA-compatible (unmanipulated) marrow grafts. Morphometric analysis revealed a very fast regeneration of CD45RO(+) and CD20(+) marrow lymphocytes in the first 2 weeks following BMT. In less than 2 months, in most patients, the post-transplant quantity of lymphocytes was comparable to that of the normal bone marrow. This finding was opposed to the profound depression of the absolute lymphocyte count in the peripheral blood. No relevant relationships could be calculated between engraftment status and the lymphocyte repopulation in the bone marrow. On the other hand, significant correlations were calculable between the development of (chronic and acute) GVHD including severity with the number of CD45RO(+) lymphocytes. In non-related graft constellations a more frequent evolution of acute grade III + IV GVHD was detectable. This complication was accompanied by an increased quantity of CD45RO(+) lymphocytes in the marrow.

Adoptively transferred gamma delta T cells indirectly regulate murine graft-versus-host reactivity following donor leukocyte infusion therapy in mice

The purpose of this study was to determine whether gamma delta T cells were able to regulate graft-vs-host (GVH) reactivity mediated by alpha beta T cells in murine recipients transplanted with MHC-mismatched marrow grafts. Studies were conducted using ex vivo-activated gamma delta T cells because this was a more clinically relevant strategy, and these cells have been shown to be capable of facilitating alloengraftment without causing GVH disease (GVHD). Coadministration of activated gamma delta T cells and naive alpha beta T cells at the time of bone marrow transplantation (BMT) significantly exacerbated GVHD when compared with naive alpha beta T cells alone. In contrast, when the administration of naive alpha beta T cells was delayed for 2 wk post-BMT, survival was significantly enhanced in mice transplanted with BM plus activated gamma delta T cells vs those given marrow cells alone. Mitigation of GVHD by activated gamma delta T cells occurred only at high doses (150 x 106) and was a unique property of gamma delta T cells, as activated alpha beta T cells were incapable of ameliorating the subsequent development of GVHD. Protection from GVHD was not due to the direct inhibition of naive alpha beta T cells by gamma delta T cells. Rather, gamma delta T cells mediated this effect indirectly through donor BM-derived alpha beta T cells that acted as the proximate regulatory population responsible for the decrease in GVH reactivity. Collectively, these data demonstrate that activated gamma delta T cells are capable of modulating the ability of MHC-incompatible nontolerant alpha beta T cells to cause GVHD after allogeneic BMT.

Tolerance and latent cellular rejection in long-term liver transplant recipients

Tolerance develops in a proportion of long-term liver transplant recipients but currently cannot be identified before an attempt at withdrawal from immunosuppression therapy. In the present study, we have examined the immunophenotypic characteristics of the cellular infiltrate in portal tracts and lobules as observed in liver biopsy specimens in relation to the outcome of subsequent withdrawal from immunosuppression therapy. Cryostat biopsy specimens from 27 long-term recipients before drug withdrawal, and from 10 patients with recent transplants who were having acute rejection, were analyzed. Immunohistochemical staining was performed for CD3+ (pan T cell), CD8+ (cytotoxic), CD4+ (helper), CD45RO+ (memory), CD45RA+ (naive), CD56+ (natural killer), CD68+ (macrophage), and CD8+ perforin+ cells. Fewer CD8+ and CD3+ cells were present in the lobular areas of biopsy specimens from patients who were successfully withdrawn from immunosuppression therapy (n = 6) compared with biopsy specimens from patients with nontolerant grafts (n = 9; 15 vs. 23 cells/high-power field [hpf] [P < .01] and 16 vs. 26 cells/hpf [P < .03], respectively) or biopsy specimens obtained during acute rejection (15 vs. 31 cells/hpf [P < .01] and 16 vs. 32 cells/hpf [P < .01]). Cell frequencies in the biopsy specimens of nontolerant long-term patients were similar to those found with acute rejection. Immunophenotyping the lobular inflammation within long-term liver allografts assists in identifying those patients in whom drug withdrawal is likely to be unsuccessful and in whom it is postulated a form of inactive, latent cellular rejection exists.

Toxicity and Efficacy of Defined Doses of CD4+ Donor Lymphocytes for Treatment of Relapse After Allogeneic Bone Marrow Transplant

Donor lymphocyte infusions (DLI) can induce remissions in patients who have relapsed after allogeneic bone marrow transplantation (BMT). However, DLI frequently also result in significant acute and/or chronic graft-versus-host disease (GVHD). Several clinical and experimental lines of evidence have suggested that CD8+ T cells play a critical role in the pathogenesis of GVHD. To develop methods to reduce the incidence of GVHD associated with DLI, we administered defined numbers of CD4+ donor T cells after ex vivo depletion of CD8+ lymphocytes to 40 patients with relapsed hematologic malignancies after allogeneic BMT. Cohorts of patients received 0.3, 1.0, or 1.5 × 108CD4+ cells/kg. Overall, 12 of 38 patients (32%) evaluable for toxicity developed acute or chronic GVHD. However, 6 of 27 patients (22%) receiving 0.3 × 108 CD4 cells/kg developed GVHD compared with 6 of 11 patients (55%) who received ≥1.0 × 108 CD4 cells/kg (P = .07). Treatment-related mortality was low (3%), with 1 death related to infection in the setting of immunosuppression for GVHD. Disease responses after CD4+ DLI were documented in 15 of 19 patients (79%) with early-phase chronic myelogenous leukemia (CML) relapse, 5 of 6 patients (83%) with relapsed multiple myeloma, and 1 patient with myelodysplasia. For patients with early-phase CML relapse, the Kaplan-Meier probability of achieving complete cytogenetic remission was 87% and the probability of complete molecular response was 78% at 1 year after DLI. The median time to complete cytogenetic response and molecular response in patients with CML was 13 weeks (range, 9 to 30 weeks) and 34 weeks (range, 10 to 56 weeks), respectively. The median time to response in patients with multiple myeloma was 26 weeks (range, 15 to 62 weeks). All patients in this trial who developed GVHD demonstrated tumor regression, but the presence of GVHD was not required for patients to achieve a response, because 48% of responding patients never developed evidence of GVHD. Two patients with CML who did not respond at dose level 1 subsequently achieved complete cytogenetic remission after a second infusion of CD8-depleted cells at dose level 2. In patients with evidence of mixed hematopoietic chimerism who achieved a complete remission after DLI, cytogenetic analysis of marrow cells also demonstrated conversion to complete donor hematopoiesis in all evaluable patients. These studies suggest that relatively low numbers of CD8-depleted donor lymphocytes are effective in inducing complete remissions in patients with stable-phase CML and multiple myeloma who have relapsed after allogeneic BMT. Because of the relatively low risk of toxicity associated with the infusion of defined numbers of CD4+donor cells, further studies can be undertaken in the setting of persistent minimal residual disease to prevent relapse after allogeneic BMT.

Toxicity and Efficacy of Defined Doses of CD4+ Donor Lymphocytes for Treatment of Relapse After Allogeneic Bone Marrow Transplant

Donor lymphocyte infusions (DLI) can induce remissions in patients who have relapsed after allogeneic bone marrow transplantation (BMT). However, DLI frequently also result in significant acute and/or chronic graft-versus-host disease (GVHD). Several clinical and experimental lines of evidence have suggested that CD8+ T cells play a critical role in the pathogenesis of GVHD. To develop methods to reduce the incidence of GVHD associated with DLI, we administered defined numbers of CD4+ donor T cells after ex vivo depletion of CD8+ lymphocytes to 40 patients with relapsed hematologic malignancies after allogeneic BMT. Cohorts of patients received 0.3, 1.0, or 1.5 × 108CD4+ cells/kg. Overall, 12 of 38 patients (32%) evaluable for toxicity developed acute or chronic GVHD. However, 6 of 27 patients (22%) receiving 0.3 × 108 CD4 cells/kg developed GVHD compared with 6 of 11 patients (55%) who received ≥1.0 × 108 CD4 cells/kg (P = .07). Treatment-related mortality was low (3%), with 1 death related to infection in the setting of immunosuppression for GVHD. Disease responses after CD4+ DLI were documented in 15 of 19 patients (79%) with early-phase chronic myelogenous leukemia (CML) relapse, 5 of 6 patients (83%) with relapsed multiple myeloma, and 1 patient with myelodysplasia. For patients with early-phase CML relapse, the Kaplan-Meier probability of achieving complete cytogenetic remission was 87% and the probability of complete molecular response was 78% at 1 year after DLI. The median time to complete cytogenetic response and molecular response in patients with CML was 13 weeks (range, 9 to 30 weeks) and 34 weeks (range, 10 to 56 weeks), respectively. The median time to response in patients with multiple myeloma was 26 weeks (range, 15 to 62 weeks). All patients in this trial who developed GVHD demonstrated tumor regression, but the presence of GVHD was not required for patients to achieve a response, because 48% of responding patients never developed evidence of GVHD. Two patients with CML who did not respond at dose level 1 subsequently achieved complete cytogenetic remission after a second infusion of CD8-depleted cells at dose level 2. In patients with evidence of mixed hematopoietic chimerism who achieved a complete remission after DLI, cytogenetic analysis of marrow cells also demonstrated conversion to complete donor hematopoiesis in all evaluable patients. These studies suggest that relatively low numbers of CD8-depleted donor lymphocytes are effective in inducing complete remissions in patients with stable-phase CML and multiple myeloma who have relapsed after allogeneic BMT. Because of the relatively low risk of toxicity associated with the infusion of defined numbers of CD4+donor cells, further studies can be undertaken in the setting of persistent minimal residual disease to prevent relapse after allogeneic BMT.

Immunohistochemical study of skin lesions in acute and chronic graft versus host disease following bone marrow transplantation

Allogeneic bone marrow transplantation (BMT) is the therapy of choice for a variety of malignant and nonmalignant disorders; however, a major constraint to successful BMT is graft versus host disease (GVHD). Skin lesions are the earliest presentation of GVHD. Donor-derived cytotoxic T lymphocytes are the effector cells responsible for lesions in the skin and other tissues. Here we show that most skin-infiltrating lymphocytes, in all forms of GVHD, are memory T cells with a predominance of CD4+ cells in the dermis and CD8+ cells in the epidermis. Relatively little attention has been focused on the adhesive phenotype of keratinocytes in GVHD. In this study, immunohistochemical analyses of skin biopsies from BMT patients with acute or chronic GVHD were conducted, with particular emphasis on antigen-presenting cells (APCs) and on keratinocytes. The distribution of APCs in the epidermis (Langerhans' cells) was investigated. Keratinocytes were analyzed for the expression of human leukocyte antigen DR locus (HLA-DR) and of a novel integrin, alpha10.1.2 beta1, which is detected in the basal layer of normal epidermis. Langerhans' cells were decreased in all grades of acute GVHD, but the epidermal APC network was reconstituted in chronic GVHD. HLA-DR was expressed by keratinocytes in grade 2 and 3 acute GVHD lesions, but not in two of three chronic GVHD cases, and in the regression phase of acute GVHD. Integrin chains alpha10.1.2 and beta1 were detected in the epidermal basal cell layer of most GVHD cases but they were also expressed in suprabasal keratinocytes of both acute and chronic GVHD. This latter finding indicates that a proliferative response uncoupled from differentiation occurs in keratinocytes in the course of GVHD.