Enhanced activation of B cells in a granulocyte colony-stimulating factor-mobilized peripheral blood stem cell graft

Mature naive B cells regulate the outcome of murine acute graft-versus-host disease in an IL-10 independent manner

Graft-versus-host disease (GVHD) is the main complication of bone marrow transplantation (BMT). T CD4+ lymphocytes are the main effector cells for disease development but other cell types can determine disease outcome through cytokine production and antigen presentation. B cells are abundant in BMT products and are involved in chronic GVHD immunopathogenesis. However, their role in acute GVHD is still unclear. Here, we studied the role of donor resting B cells in a model of acute GVHD. Animals receiving transplants depleted of B cells presented a more severe disease, indicating a protective role for B cells. Mice transplanted with IL-10 KO B cells developed GVHD as severe as those receiving WT B cells. Besides that, mice transplanted with MHC II deficient B cells and as so, unable to present antigen to CD4+ T cells, developed as severe GVHD as animals transplanted without B cells. This result suggests that protection provided by mature naive B cells depends on antigen presentation and not IL-10 production by B cells. In the absence of donor B cells, transplanted mice exhibited disorganized lymphoid splenic tissue. Additionally, donor B cell depletion diminished the follicular T (Tfh)/T effector (Teff) ratio suggesting that protection was correlated with a shift to Tfh differentiation, reducing the number of effector T cells. Importantly, the Tfh/Teff shift impacts disease outcome since observed proinflammatory cytokine levels and tissue damage in target organs were consistent with disease protection. The role of transplanted B cells in the outcome of BMT and the development of acute GVHD should be carefully studied, since these cells are abundant in BMT products and are potent modulator and effector cells in allogeneic response. Extended Abstract Background: B cells are widely known for their ability to produce antibodies. In addition, B cells can act efficiently as antigen-presenting cells, implying the mutual regulation of both T and B lymphocyte subsets. T cell help for B cells has been known for more than 50 years; however, B cell help for T cells, especially regarding the modulation of follicular and regulatory phenotypes, had only lately been explored. Here, we studied the role of resting B cells in a model of systemic inflammatory disease mediated by T cells, graft-versus-host disease (GVHD), which is the main complication of allogeneic bone marrow transplantation. Objetive: The objective of this paper is to investigate the role of donor B cells in acute Graft-versus-Host Disease.

STUDY DESIGN

To investigate the role of donor B cells in aGVHD, we used a full MHC-mismatched bone marrow transplantation model. We infused C57BL/6 BM cells along with splenocytes depleted or not of B220⁺ cells into lethally irradiated BALB/c mice. We also used B cells from IL-10 KO mice to investigate the role of IL-10 produced by donor B cells and B cells from mice which cannot express MHC-II (CIITA KO) to investigate the role of cognate interaction between donor B and T cells.

RESULTS

Animals receiving transplants depleted of B cells presented a more severe disease, showing the existence of B cell-dependent protection. This protection was dependent on the T cell-B cell cognate interaction but not on IL-10 or Treg induction. In the absence of donor B cells, transplanted mice exhibited fewer GCs and a lower follicular T (Tfh)/T effector (Teff) ratio than mice transplanted in the presence of B cells. Protection was correlated with a shift to Tfh differentiation, reducing the number of effector cells. Importantly, the Tfh/Teff shift impacts disease outcome with less T cell-mediated disease due to more B cell-dependent Tfh generation with fewer effector T cells and lower proinflammatory cytokine levels detected in target organs.

CONCLUSION

We show that B-cell depleted bone marrow transplantation leads to a more severe disease, with earlier mortality related to increased organ damage. Such differences depend on cognate interactions between T cells and B cells, are IL-10 independent and are related to a shift in the differentiation of lymphocytes from the follicular helper phenotype to the effector phenotype. Therefore, Teffs, which are circulating cells, become relatively more numerous and can reach and damage the target tissues. These results point to caution in the early posttransplantation elimination of donor B cells. It is not a matter of eliminating only antibody-forming cells or cells that mediate Tfh generation but of B cells, which interact and modulate T cell activity, impacting a disease that is not antibody mediated.

Risk factors associated with the development of moderate to severe chronic graft-versus-host disease after non-myeloablative conditioning allogeneic stem cell transplantation in patients with AML or MDS

Moderate to severe chronic graft-versus-host disease (cGVHD) is associated with high morbidity, hospital dependency and poor quality of life. In this study, we analyzed a well-defined consecutive series of 98 patients with acute myelogenous leukemia/myelodysplastic syndrome (AML/MDS) who received allogeneic stem cell transplantation with non-myeloablative (NMA) conditioning to determine risk factors associated with the severity of cGVHD. cGVHD was defined according to the 2005 National Institute of Health consensus criteria. Transfusions before transplantation, presence of HLA antibodies, composition of the graft (CD3+, CD19+, CD34+ cells), sibling or matched unrelated donor, female donor to male recipient, CMV serology and the development of acute GVHD (aGVHD), were considered potential risk factors. Multivariate Cox regression analysis identified the number of CD19+ 10⁶/kg (HR 2.79; 95% CI 1.35–5.74), CD3+ 10⁶/kg (HR 2.18; 95% CI 1.04–4.59) infused cells and the presence of patient HLA antibodies before transplantation (HR 2.34; CI 1.11–4.95) as significant risk factors for the development of moderate to severe cGVHD. In summary, we identified in a small, but well-defined cohort, 3 risk factors associated with the severity of cGVHD that should be validated in a larger multi-center study.

Immune reconstitution following hematopoietic stem cell transplantation using different stem cell sources

Introduction: Adequate immune reconstitution post-HSCT is crucial for the success of transplantation, and can be affected by both patient- and transplant-related factors. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses is performed to investigate immune recovery posttransplant. In this review, we discuss the pattern of immune recovery in the post-transplant period focusing on the impact of stem cell source (bone marrow, peripheral blood stem cells, and cord blood) on immune recovery and HSCT outcome. We examine the impact of serotherapy on immune reconstitution and the need to tailor dosing of serotherapy agents when using different stem cell sources. We discuss new techniques being used particularly with cord blood and haploidentical grafts to improve immune recovery in each scenario. Expert opinion: Cord blood T cells provide a unique CD4+ biased immune reconstitution. Initial studies using targeted serotherapy with cord grafts showed improved immune recovery with limited alloreactivity. Two competing haploidentical approaches have developed in recent years including TCRαβ/CD19 depleted grafts and post-cyclophosphamide haplo-HSCT. Both approaches have comparable survival rates with limited alloreactivity. However, delayed immune reconstitution is still an ongoing problem and could be improved by modified donor lymphocyte infusions from the same haploidentical donor.

The importance of graft cell composition in outcome after allogeneic stem cell transplantation in patients with malignant disease

BACKGROUND

Graft-versus-host disease (GVHD) and relapse remain majobstacles ftreatment success in allogeneic hematopoietic stem cell transplantation (HSCT). In the present study, we evaluated the immune cell profile of the graft to outcome after HSCT.

STUDY DESIGN AND METHOD

Flow cytometry data of graft cell subsets [CD34⁺ , CD3⁺ , CD19⁺ , CD4⁺ , CD8⁺ , CD3-CD56⁺ CD16⁺ , CD4⁺ CD127^low CD25^high ] from G-CSF primed peripheral blood stem cell (PBSC) donors was collected retrospectively from 299 patients with hematological malignancies undergoing HSCT between 2006 and 2013. The association to overall survival, transplant-related mortality (TRM), GVHD and probability of relapse was analyzed. Patients outcome from HLA-identical sibling (Sib) (n = 97) and unrelated donors (URD) (n = 202) were analyzed separately as all URD patients received anti-thymocyte globulin (ATG).

RESULTS

Five-year overall survival was similar in the two cohorts (68% (Sib) vs 65% (URD)). The relapse incidence was significantly lower in the Sib cohort (24% vs 35%, P = 0.04). Multivariate analysis in the URD group revealed an association between a higher CD8⁺ dose and less relapse (HR, 0.94; 95%CI, 0.90-0.98; P = 0.006) as well as an association between higher CD34⁺ dose and both higher TRM (HR, 1.09; 95%CI, 1.02-1.20; P = 0.02) and relapse (HR, 1.09; 95%CI, 1.01-1.17; P = 0.025). The Sib analysis showed an association between a higher graft CD19⁺ dose and more severe acute GVHD (HR, 1,09; 95%CI, 1.03-1.15; P = 0.003) and TRM (HR, 1.09; 95%CI, 1.01-1.17; P = 0.036). In addition, a higher CD4⁺ graft content was associated to an increased risk for chronic GVHD (HR, 1.02; 95%CI 1.00-1.04; P = 0.06).

CONCLUSION

These data indicate an importance of PBSC dongraft composition in patients with a hematological malignancy.

Transient hemolysis due to anti-D and anti-A1 produced by engrafted donor's lymphocytes after allogeneic unmanipulated haploidentical hematopoietic stem cell transplantation

BACKGROUND

Development of de novo alloantibodies against recipient's red blood cell (RBC) antigens by engrafted donor's lymphocytes is a known phenomenon in the setting of allogeneic hematopoietic stem cell transplantation (HSCT). This situation is usually clinically insignificant. We report a case of early clinically relevant hemolytic anemia in a blood group A₁ D+ patient, due to a limited production of anti-D and anti-A₁ produced by nonpreviously sensitized newly engrafted donor's immune system.

CASE REPORT

A 31-year-old Caucasian woman, blood group A₁ , D+, with Hodgkin's lymphoma, received an unmanipulated haploidentical allogeneic peripheral blood HSCT after a nonmyeloablative conditioning regimen. Donor blood group was A₂ B, D-. The patient had an uneventful course until Day +34, when she developed clinically significant hemolytic anemia with a positive direct antiglobulin test. Anti-D and anti-A₁ produced by the donor-engrafted lymphocytes were detected both in serum and in eluate. The hemolysis produced an accelerated group change, turning the patient's ABO group into A₂ B 2 weeks after the detection of the alloantibodies. As the residual patient's RBCs progressively disappeared, anti-D and anti-A₁ production decreased and were not detected in serum by Day +41.

CONCLUSION

This case illustrates that de novo alloantibody production against ABO and D antigens by the newly engrafted donor's lymphocytes can occasionally cause clinically significant anemia. To our knowledge, this is the first case reported of clinically significant hemolytic anemia due to a transient anti-D anti-A₁ alloimmunization after T-cell-repleted haploidentical HSCT.

Analysis of Factors that Influence Hematopoietic Recovery in Autologous Transplanted Patients with Hematopoietic Stem Cells from Peripheral Blood

BACKGROUND:

Successful hematopoietic stem cell transplantation (HSCT) requires a rapid and durable hematopoietic recovery.

AIM:

The aim of our study was to analyse factors that influence hematopoietic recovery after autologous HSCT.

MATERIALS AND METHODS:

Multiple regression analysis was used to analyse factors affecting neutrophil and platelet engraftment in 90 autologous transplanted patients – 30 with acute myeloid leukaemia (AML), 30 with lymphoma and 30 with multiple myeloma (MM) from 2008 till 2016.

RESULTS:

The neutrophil recovery in AML patients was significantly influenced by transfusion support with random-donor platelets, sex and number of transplanted mononuclear cells (MNC) and CD34+ cells; and in lymphoma patients, it was influenced by sex, age, mobilisation strategy and some transplanted MNC. The influence of investigated factors on neutrophil engraftment in MM patients was not statistically significant. The platelet recovery in AML patients was influenced by transfusion support with random-donor platelets; in lymphoma patients, it was influenced by sex, age, time from diagnosis to harvesting and time from diagnosis to HSCT; and in MM patients it was influenced by transfusion support with random-donor platelets.

CONCLUSION:

Additional studies are necessary to better understanding of engraftment kinetic to improve the safety of HSCT and to minimise potential complications and expenses related to HSCT.

Adult Nephrotic Syndrome after Hematopoietic Stem Cell Transplantation: Renal Pathology is the Best Predictor of Response to Therapy

Nephrotic syndrome (NS) after allogeneic hematopoietic stem cell transplantation (HSCT) is a rare phenomenon usually associated with graft-versus-host disease (GVHD). This systematic review of post-HSCT NS cases reported in the literature aimed to identify risk factors and unique features of the disease in this clinical setting. One hundred sixteen cases of post-HSCT NS published in the English literature between 1988 and 2015 were revealed and analyzed. The median onset of NS was 20.5 months (range, 3 to 174) post-HSCT. NS development was associated with acute or chronic GVHD in 87.2% of cases. Membranous nephropathy (MGN) was the most frequent pathology (65.5%), followed by minimal change disease (MCD) (19%). Complete remission of the NS was achieved in 63.5% of patients (59.1% of MGN cases and 81.3% of MCD cases; P = .15). Patients presenting with MCD recovered at a median of 1.75 months (range, 1 to 12) and with MGN a median of 7 months (range, 1 to 53) (P = .001). NS was treated with corticosteroids alone in 16.8% of patients and with a combination of corticosteroids and other immunosuppressive agents in 73.5% of patients. Univariate analysis failed to identify a single predictive factor of response to therapy. In conclusion, post-HSCT NS usually develops concomitant to GVHD and is associated with high rates of response to therapy. Although most patients were treated with a combination of immunosuppressive drugs, single-agent therapy with steroids may be sufficient in some cases.

Monitoring pharmacologically induced immunosuppression by immune repertoire sequencing to detect acute allograft rejection in heart transplant patients: a proof-of-concept diagnostic accuracy study

BACKGROUND

It remains difficult to predict and to measure the efficacy of pharmacological immunosuppression. We hypothesized that measuring the B-cell repertoire would enable assessment of the overall level of immunosuppression after heart transplantation.

METHODS AND FINDINGS

In this proof-of-concept study, we implemented a molecular-barcode-based immune repertoire sequencing assay that sensitively and accurately measures the isotype and clonal composition of the circulating B cell repertoire. We used this assay to measure the temporal response of the B cell repertoire to immunosuppression after heart transplantation. We selected a subset of 12 participants from a larger prospective cohort study (ClinicalTrials.gov NCT01985412) that is ongoing at Stanford Medical Center and for which enrollment started in March 2010. This subset of 12 participants was selected to represent post-heart-transplant events, with and without acute rejection (six participants with moderate-to-severe rejection and six without). We analyzed 130 samples from these patients, with an average follow-up period of 15 mo. Immune repertoire sequencing enables the measurement of a patient's net state of immunosuppression (correlation with tacrolimus level, r = -0.867, 95% CI -0.968 to -0.523, p = 0.0014), as well as the diagnosis of acute allograft rejection, which is preceded by increased immune activity with a sensitivity of 71.4% (95% CI 30.3% to 94.9%) and a specificity of 82.0% (95% CI 72.1% to 89.1%) (cell-free donor-derived DNA as noninvasive gold standard). To illustrate the potential of immune repertoire sequencing to monitor atypical post-transplant trajectories, we analyzed two more patients, one with chronic infections and one with amyloidosis. A larger, prospective study will be needed to validate the power of immune repertoire sequencing to predict rejection events, as this proof-of-concept study is limited to a small number of patients who were selected based on several criteria including the availability of a large number of samples and the absence or presence of rejection events.

CONCLUSIONS

If confirmed in larger, prospective studies, the method described here has potential applications in the tailored management of post-transplant immunosuppression and, more broadly, as a method for assessing the overall activity of the immune system.

The chemokine system in allogeneic stem-cell transplantation: a possible therapeutic target?

Further improvements in allogeneic stem-cell transplantation will probably depend on a better balance between immunosuppression to control graft-versus-host disease and immunological reconstitution sufficient to ensure engraftment, reduction of infection-related mortality and maintenance of post-transplant antileukemic immune reactivity. The chemokine network is an important part of the immune system, and, in addition, CXCL12/CXCR4 seem to be essential for granulocyte colony-stimulating factor-induced stem-cell mobilization. Partial ex vivo graft T-cell depletion based on the expression of specific chemokine receptors involved in T-cell recruitment to graft-versus-host disease target organs may also become a future therapeutic strategy; an alternative approach could be pharmacological inhibition (single-receptor inhibitors or dual-receptor inhibitors) in vivo of specific chemokine receptors involved in this T-cell recruitment. Future clinical studies should therefore be based on a better characterization of various immunocompetent cells, including their chemokine receptor profile, both in the allografts and during post-transplant reconstitution.

Specific factors influence the success of autologous and allogeneic hematopoietic stem cell transplantation

Successful hematopoietic stem cell transplantation (HSCT), both autologous and allogeneic, requires a rapid and durable engraftment, with neutrophil (>500/µL) and platelet (>20,000/µL) reconstitution. Factors influencing engraftment after autologous or allogeneic HSCT were investigated in 65 patients: 25 autologous peripheral stem cell transplantation (PBSCT) and 40 allogeneic bone marrow transplantation (BMT) patients. The major factor affecting engraftment was the graft source for HSCT. Neutrophil and platelet recovery were more rapid in autologous PBSCT than in allogeneic BMT [neutrophil occurring in median on day 10.00 (09.00/11.00) and 19.00 (16.00/23.00) and platelet on day 11.00 (10.00/13.00) and 21.00 (18.00/25.00), respectively; p < 0.0001]. The type of disease also affected engraftment, where multiple myeloma (MM) and lymphoma showed faster engraftment when compared with leukemia, syndrome myelodysplastic (SMD) and aplastic anemia (AA) and MM presented the best overall survival (OS) in a period of 12 months. Other factors included the drug used in the conditioning regimen (CR), where CBV, melphalan (M-200) and FluCy showed faster engraftment and M-200 presented the best OS, in a period of 12 months and age, where 50–59 years demonstrated faster engraftment. Sex did not influence neutrophil and platelet recovery.

Persistence of lymphocyte function perturbations after granulocyte-colony-stimulating factor mobilization and cytapheresis in normal peripheral blood stem cell donors

BACKGROUND

The short-term effects of granulocyte-colony-stimulating factor (G-CSF) have been extensively studied, but recent reports of G-CSF-induced genetic perturbations raised concerns regarding its long-term safety. In this respect, duration of G-CSF-induced perturbations has been less studied than short-term effects and needs to be evaluated.

STUDY DESIGN AND METHODS

G-CSF mobilization-induced immunologic alterations were prospectively analyzed in a cohort of 24 healthy donors. Blood samples were taken before G-CSF administration; at the time of administration; and at 1, 3, 6, and 12 months and analyzed for blood cell counts and in vitro cytokines (interleukin [IL]-2, -8, and -10) and immunoglobulin production, quantified in the culture supernatant of peripheral blood mononuclear cells (PBMNCs) after, respectively, phytohemagglutinin and pokeweed mitogen stimulation.

RESULTS

Platelet, granulocyte, monocyte, B, and dendritic blood cell counts as well as the IL-2, -8, and -10 secretion by PBMNCs, perturbed at the time of G-CSF mobilization, returned to baseline values at 1 month, with T-cell and natural killer cell counts recovering at 3 months. In vitro immunoglobulin production was increased up to 6 months after mobilization.

CONCLUSION

Although assessment of the potential long-term risk of G-CSF administration will require prolonged observation of larger cohorts, our data show that the duration of immunologic perturbations may be more persistent than previously anticipated, especially for B-cell functional alterations. Most perturbations remain, however, transient with a return to baseline values within 1 year.

The role of B cells in the pathogenesis of graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation is an established treatment modality for malignant and nonmalignant hematologic diseases. Acute and chronic graft-versus-host diseases (GVHDs) are a major cause of morbidity and mortality after allogeneic stem cell transplantation. T cells have been identified as key players in the graft-versus-host reaction and, therefore, most established drugs used against GVHD target T cells. Despite our knowledge on the pathogenesis of the GVH reaction, success of established therapies for prevention and treatment of GHVD is unsatisfactory. Recently, animal and human studies demonstrated that B cells are involved in the immunopathophysiology of acute and chronic GVHD. Early phase clinical trials of B-cell depletion with rituximab have shown beneficial effects on both acute and chronic GVHD. This review summarizes the current experimental and clinical evidence for the involvement of B cells in the pathogenesis of acute and chronic GVHD and discusses the clinical implications for the management of patients undergoing allogeneic stem cell transplantation.

B-cell concentration in the apheretic product predicts acute graft-versus-host disease and treatment-related mortality of allogeneic peripheral blood stem cell transplantation

BACKGROUND

The influence of the graft composition on the clinical outcome after allogeneic peripheral blood stem cell (PBSC) transplantation is not well established.

METHODS

The cellular composition of the apheretic products obtained from 63 human leukocyte antigen-identical siblings was prospectively correlated with the outcome of patients with hematological malignancies undergoing an allogeneic PBSC transplant after myeloablative conditioning. The concentration of nuclear, mononuclear, CD34+, T-cell subsets, B cells, and natural killer cells in the graft has been analyzed.

RESULTS

In univariate analysis, acute graft-versus-host disease (GVHD) correlated with the disease (P=0.002), with the phase of disease at transplant (P=0.01), and with the number of CD20+ cells infused (P=0.05). In multivariate analysis, a dose of CD20+ cells in the graft higher than the median dose remained the only factor negatively affecting the incidence of acute GVHD (P=0.01; 95% confidence interval [CI]: 0.12-0.78). In univariate analysis, treatment-related mortality (TRM) correlated with the disease (P=0.04) and was negatively affected by a dose of infused B cells greater than the median value (28% versus 50%; P=0.02). In multivariate analysis, TRM was close to statistical correlation with the dose of CD20+ cells (P=0.06; 95% CI: 0.02-1.05). No other clinical parameter was influenced by the composition of the graft.

CONCLUSIONS

Our results suggest that the concentration of B cells in the apheretic product may predict the incidence of acute GVHD and TRM in patients undergoing an allogeneic PBSC transplantation and open the way to the new preventive and therapeutic strategies for the management of GVHD.

Nephrotic syndrome after allogeneic hematopoietic stem cell transplantation as a late complication of chronic graft-versus-host disease

BACKGROUND

This study aims to determine the incidence and outcome of nephrotic syndrome in patients who underwent allogeneic stem cell transplantation in a single center.

METHODS

Records of 279 adult patients with hematological diseases who underwent allogeneic hematopoietic stem cell transplantation were analyzed to evaluate the incidence and outcome of nephrotic syndrome. The diagnosis of chronic graft-versus-host disease was based on clinical evidence with histological confirmation whenever possible.

RESULTS

Of the 279 patients, 105 with a minimum follow-up of 100 days developed chronic graft-versus-host disease: six of these had nephrotic syndrome. The cumulative incidence of nephrotic syndrome was 8% at day +1,681. Patients grafted with peripheral blood stem cells had a higher probability of developing nephrotic syndrome than did those grafted with bone marrow: 24% and 3%, respectively. The pathological diagnosis was membranous glomerulonephritis in four patients, and minimal change disease in one; the diagnosis could not be histologically confirmed in the sixth patient. All patients had extensive chronic graft-versus-host disease and were receiving treatment with cyclosporine A and steroids (four patients). Response to immunosuppressive therapy with cyclosporine A and steroids was achieved in all patients at a median time of 12 weeks after transplantation.

CONCLUSION

Patients with chronic graft-versus-host disease may be considered to be at risk of nephrotic syndrome: careful monitoring of renal function is advisable, particularly in patients receiving allogeneic peripheral stem cell grafts.

Immune restoration following hematopoietic stem cell transplantation: an evolving target

Hematopoietic stem cell transplantation (HSCT) is the definitive cure for many malignant and nonmalignant diseases. However, delays in immune reconstitution (IR) following HSCT significantly limit the success of transplantation and increase the risk for infection and disease relapse in the transplant recipient. Therefore, ways to measure and to manipulate immune recovery following HSCT are emerging and their success depends directly upon an enhanced understanding for the underlying mechanisms responsible for reconstituted immunity and hematopoiesis. Recent discoveries in the activation, function, and regulation of dendritic cell (DC), natural killer (NK) cell, and T-lymphocyte subtypes have been critical in developing immunotherapies used to prevent graft-versus-host disease and to enhance graft-versus-leukemia. For example, regulatory T cells that induce tolerance and NK receptor-tumor ligand disparities that result in tumor lysis are being used to minimize GVHD and tumor burden, respectively. Furthermore, expansion and modulation of immune effector cells are being used to augment hematopoietic and immune recovery and to decrease transplant-related toxicity in the transplant recipient. Specifically, DC expansion and incorporation into antitumor and anti-microbial vaccines is fast approaching application into clinical trials. This paper will review our current understanding for IR following HSCT and the novel ways in which to restore immune function and decrease transplant-related toxicity in the transplant recipient.

Lymphocyte recovery as a positive predictor of prolonged survival after autologous peripheral blood stem cell transplantation in T-cell non-Hodgkin's lymphoma

We performed a retrospective study on recovery and survival of patients with T-cell NHL after autologous peripheral blood stem cell transplantation (APBSCT). Of a total of 39 patients with high-risk T-cell NHL, 33 were analyzed. Six patients who experienced early treatment mortality without full lymphocyte recovery were excluded. We chose absolute lymphocyte count (ALC) recovery as 1000 cells/microl as a cutoff value. ALC recovery day was defined as the first of 3 consecutive days with ALC above 1000 cells/microl. Univariate analysis revealed that age younger than 45 years, good international prognostic index, chemosensitive disease prior to APBSCT, and early ALC recovery (1000 cells/microl within 25 days of APBSCT) were predictors of prolonged survival. Multivariate analyses confirmed that chemosensitive disease prior to APBSCT and early ALC recovery were strongly associated with better overall survival (OS) (P=0.005 and 0.011, respectively) and progression-free survival (PFS) (P<0.001 and P=0.013, respectively). Our finding, that ALC recovery > or =1000 cells/microl is an independent predictor of OS and PFS in T-cell NHL after APBSCT, suggests that earlier immune recovery may contribute to longer survival.

B Cell Allogeneic Responses after Hematopoietic Cell Transplantation: Is It Time to Address this Issue?

To date, B cell responses have retained less attention than T, natural killer or dendritic cell responses in the alloreactive conflict after allogeneic hematopoietic cell transplantation (HCT). Here, we discuss recent clinical and experimental data supporting a role of allogeneic B cell responses in graft-host interactions after HCT. We report results in a murine model of reduced intensity conditioning transplantation (RICT) showing that host B cells can be involved in chronic graft-versus-host disease occurrence. We also describe the control of antidonor alloresponses by intravenous simultaneous infusion of apoptotic cells with allogeneic hematopoietic grafts.

Blood versus marrow hematopoietic allogeneic graft

Allogeneic G-CSF-mobilized blood cell transplantation (BCT), an alternative to allogeneic bone marrow transplantation (BMT), is associated with enhanced engraftment and accelerated hematopoietic recovery. In addition, immune reconstitution and overall alloreactivity after BCT versus BMT differ significantly. Indeed, despite an increased number of donor T cells infused, the incidence of acute graft-versus-host disease (GvHD) after BCT appears to remain identical or lesser than after BMT. On the other hand, a higher risk of chronic GvHD has been reported after BCT. In a SFGM phase III trial, 101 patients with early leukemia and an HLA-matched sibling donor randomly received a BCT or BMT. BCT was associated with a higher number of infused CD34+ cells, accelerated platelet and neutrophil reconstitution, fewer platelet transfusions and similar acute GvHD incidence. However, chronic GvHD occurred more frequently after BCT. With a median follow-up of 20 months, relapse, survival and leukemia-free survival were not different. In the course of this study, immune parameters related to the graft as well as to early reconstitution were prospectively examined. T cells subsets, B cells, NK cells and monocytes numbers were significantly higher in BC grafts (versus BM). T cells in BC grafts were less activated than in BM grafts. Frequency of IFN-gamma, IL-2- and TNF-alpha-secreting cells and single-cell IFN-gamma production potential was reduced in BC graft. One month after BCT, blood T-cell counts were 3-fold higher than after BMT. Moreover, post-BCT T cells were less activated and counts correlated with the number of T cells infused with the graft, which was not the case after BMT. Several acute hemolysis episodes, resulting from anti-A and/or -B donor-derived Ab directed at Ag present on recipient red blood cells (minor ABO mismatch), have been described after BCT. Recipients indeed exhibited significantly increased anti-A and/or -B Ab titers after BCT, particularly in the setting of a "minor" ABO mismatch. Furthermore, the frequency of anti-HLA Ab early after BCT was significantly increased (despite the reduction in platelet transfusion requirements). The higher number of activated B cells and/or CD4 T cells and monocytes in a BCT graft and/or the higher number of circulating CD4 T- and B-cells after BCT could be associated with the enhanced alloAb production. G-CSF-induced TH2 cytokine profile of the T cells present in the graft could also be contributive. Recent studies have determined that BC grafts contained a higher number of type 2 dendritic cells (DC2), themselves associated with high frequencies of TH2 CD4+ cells. Since chronic GvHD is associated with the occurrence of Ab-mediated auto-immune-like syndromes, it is tempting to speculate that a higher incidence of chronic GvHD may result from these findings. In conclusion, BCT results in clinically relevant distinct hematopoietic and immune reconstitution patterns.

Treatment of chronic graft-versus-host disease with anti-CD20 chimeric monoclonal antibody

We reviewed the clinical outcome of 8 patients with steroid-refractory chronic graft-versus-host disease (GVHD) who received an anti-CD20 chimeric monoclonal antibody (rituximab). Rituximab was given by intravenous infusion at a weekly dose of 375 mg/m(2) for 4 weeks. All patients had received extensive treatment with various immunosuppressive agents; 6 patients had also received extracorporeal photopheresis. All patients had extensive chronic GVHD with diffuse or localized sclerodermoid GVHD and xerophthalmia. Other extracutaneous involvements included cold agglutinin disease with the Raynaud phenomenon, membranous glomerulonephritis, and restrictive or obstructive lung disease. Four patients responded to treatment with ongoing resolution or improvement ranging from 265 to 846 days after therapy, despite recovery of B cells in 3 patients. Rituximab seems to have significant activity in the treatment of refractory chronic GVHD and should be considered for further study in patients with early disease. This study suggests a participating role of B cells in the pathogenesis of chronic GVHD.

Massive immune hemolysis after non-myeloablative allogeneic peripheral blood stem cell transplantation with minor ABO-incompatibility

A 35-year-old male, blood group B, Rh(D)+ type, received an allogeneic peripheral blood stem cell (PBSC) transplant after a non-myeloablative regimen of fludarabine and cyclophosphamide for resistant gammadelta cutaneous T-cell lymphoma (CTCL). The donor was his HLA-identical brother, blood group O, Rh(D)+ type. Graft-versus-host disease (GVHD) prophylaxis was performed with cyclosporine alone. On day +8, massive immune hemolysis occurred, followed by acute renal failure. Hemodialysis was performed eight times until recovery of renal function on day +24. The risk of delayed immune hemolysis after non-myeloablative allogeneic PBSC transplantation with minor ABO-incompatibility must be considered.