Fludarabine Treatment Is Associated with Depletion of Host CD4+CD25high, FOXP3+, CTLA-4+ Cells and Increased Incidences of Full Donor Chimerism and GVHD in Non-Myeloablative Haploidentical Hematopoietic Cell Transplant Recipients.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2898-2898
Author(s):  
Juanita M. Shaffer ◽  
Jean Villard ◽  
Terry Means ◽  
David Dombkowski ◽  
Bimalangshu Dey ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Hematopoietic Cell ◽  
Cell Depletion ◽  
Cell Recovery ◽  
Myeloablative Conditioning ◽  
T Cell Depletion ◽  
Donor Chimerism

Abstract Purpose: To evaluate T cell recovery and donor chimerism following haploidentical hematopoietic cell transplantation (HCT) with a non-myeloablative conditioning approach that includes T cell depletion of host and donor and delayed DLI. Methods: Eighteen patients, 3 cohorts of 4 patients each and 1 cohort of 6 evaluable patients/10 transplanted, with chemorefractory hematologic malignancies, received related HLA 1–3 of 6, A, B, or DR antigen mismatched donor HCT after non-myeloablative conditioning with Medi-507 (anti-CD2 humanized mAb; Biotransplant, Inc.), cyclophosphamide, thymic irradiation and peritransplant cyclosporine. The patients in Protocols A received a MEDI-507 test dose of 0.1 mg/kg on Day -2 followed by 0.6 mg/kg on Days −1, 0 and +1 and transplantation of unmanipulated bone marrow. In Protocol B, the timing and dose of Medi-507 was modified. The patients in Protocol C and D received the latter Medi-507 protocol, but were given Isolex ®-selected CD34+ cells from G-CSF mobilized PBSC. Protocol D differs from Protocol C with the addition of fludarabine to more reliably achieve sustained chimerism. Donor leukocyte infusions were administered in an effort to convert mixed to full donor chimerism and to achieve a graft-versus-tumor effect. Chimerism was measured by peripheral blood microsatellite markers or by flow cytometry using HLA-specific mAbs. T cell recovery and phenotype were followed by flow cytometry. Because a high percentage of CD4 T cells post- transplant were CD25high, we performed quantitative RTPCR for Foxp3 and CTLA-4 on sorted PBMC populations. Results: T cell depletion early post-HCT was detected in all patients. There was a marked difference in the percentage of graft acceptance/loss, GVHD prevalence, and T cell phenotype related to each protocol modification. The majority (>90%) of CD4 T cells appearing in the first 100 days post-SCT were CD45RO+/CD45RA- “memory” cells and CD8 T cells were CD45RO+CD45RA-/CD62L-. In addition, a remarkably high percentage (19.5–75%, mean 38.1%) of CD4 T cells expressed high levels of CD25 in recipients of Protocols A, B, and C early post-HCT. CD25 expression decreased as T cell counts increased. By quantitative RTPCR, we found that sorted CD25highCD4 T cells expressed Foxp3 and CTLA-4, consistent with a regulatory phenotype. The addition of fludarabine in Protocol D resulted in an overall reduction in the percentage of peripheral CD4CD25high T cells compared to Protocol C at 4 weeks post-HCT (C 23.43% +/−4.7% versus D 2.1% +/− 0.9%, p<0.00005). The addition of fludarabine improved sustained engraftment from 2/4 in Protocol C to 5/6 in Protocol D. In Protocol C, T cell chimerism conversion occurred following DLI in 2/4 patients with no or grade II skin-limited GVHD. In Protocol D, full or near full donor chimerism was achieved in 5/6 patients, 3 spontaneously and 2 following DLI, and grade I–IV GVHD developed in 5/6 patients. Conclusions: These data suggest that the addition of fludarabine may increase the incidence of sustained and full donor chimerism. Fludarabine efficiently depleted host CD4+CD25high Foxp3+ cells, which may have a regulatory role, preventing spontaneous chimerism conversion and associated GVHD.

Reconstitution of CD52-Negative CD4 T Cells after Alemtuzumab-Based T Cell Depleted Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1182-1182
Author(s):  
Eva M Wagner ◽  
Aline N Lay ◽  
Sina Wenzel ◽  
Timo Schmitt ◽  
Julia Hemmerling ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Lymphocytic Leukemia ◽  
Cell Depletion ◽  
Down Regulation ◽  
T Cell Depletion ◽  
Hematopoietic Stem

Abstract The human CD52 molecule is the target of the monoclonal antibody Alemtuzumab, which is used for treating patients with chemo-refractory chronic lymphocytic leukemia as well as for T cell depletion (TCD) in the context of allogeneic hematopoietic stem cell transplantation (HSCT). The molecule is expressed on the surface of lymphocytes, dendritic cells and to a lesser extent on blood-derived monocytes. Previously, investigators have demonstrated that the surface expression of CD52 on T cells is down-regulated after in vitro incubation with Alemtuzumab. By treating purified human CD4 T cells over 4 hours with 10 μg/mL Alemtuzumab in medium supplemented with 10% human AB serum in vitro, we observed a strong decrease of CD52 expression by flow cytometry with a maximum 3–7 days after incubation. The CD52 down-regulation was also found at weaker intensity on CD8 T cells. From previous studies in chronic lymphocytic leukemia patients, it is known that Alemtuzumab treatment also leads to a down-regulation of CD52 on T cells in vivo. However, similar experiments have not been performed in allogeneic HSCT patients receiving Alemtuzumab in vivo for T cell depletion. We therefore analyzed the expression of CD52 on human peripheral blood mononuclear cells isolated at repeated time points from 22 allogeneic HSCT patients after reduced-intensity conditioning with fludarabine and melphalan and in vivo T cell depletion with Alemtuzumab (100 mg). Half of the patients received prophylactic CD8-depleted donor lymphocyte infusions (DLI) to promote immune reconstitution. By flow cytometry, we observed that the CD52 expression on monocytes, B cells, and natural killer cells remained unaltered after transplantation and was not influenced by the application of DLI. In contrast, the majority of CD4 T cells were CD52-negative (median, 72%) after transplantation and they remained CD52-negative in patients who did not receive DLI throughout the first year after HSCT. The permanent lack of CD52 expression could not be explained by a continuous effect of Alemtuzumab, because earlier studies have shown that the antibody is not present in active plasma concentrations beyond day +60 after HSCT. In contrast, patients receiving CD8-depleted DLI demonstrated a significant increase in the proportion of CD52-positive CD4 T cells. In three of our patients (DLI: n=2, non-DLI: n=1) we analyzed the donor chimerism of CD52-positive and CD52-negative CD4 T cells sorted with high purity by flow cytometry. Three months after HSCT (before DLI), the proportion of donor T cells was clearly higher among the CD52-negative compared to the small proportion of CD52-positive cells in all patients (44% vs. 10%, 83% vs. 0%, and 100% vs. 40%). In the patient who did not receive DLI, the donor T cell chimerism remained mixed in the CD52-negative and CD52-positive fractions on days 200 (CD52-negative: 95%; CD52-positive: 15%) and 350 (CD52-negative: 92%; CD52-positive: 65%). In contrast, the two patients receiving CD8-depleted DLI showed a strong increase in the proportion of CD52-positive CD4 T cells that were of complete donor origin. Altogether, CD52 is permanently down-regulated in reconstituting CD4 T cells following HSCT with an Alemtuzumab-based TCD regimen unless DLI are applied. Our data support the idea of an active mechanism for CD52 down-regulation in CD4 T cells that is not related to B cells and natural killer cells and that appears to differently affect donor and host T cells, respectively.

scholarly journals The Hitchhiker Guide to CD4+ T-Cell Depletion in Lentiviral Infection. A Critical Review of the Dynamics of the CD4+ T Cells in SIV and HIV Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Quentin Le Hingrat ◽  
Irini Sereti ◽  
Alan L. Landay ◽  
Ivona Pandrea ◽  
Cristian Apetrei
Keyword(s):  
T Cells ◽  
T Cell ◽  
Viral Replication ◽  
Cd4 T Cells ◽  
Microbial Translocation ◽  
T Cell Subsets ◽  
Cell Depletion ◽  
Cell Recovery ◽  
T Cell Depletion ◽  
Siv Infection

CD4+ T-cell depletion is pathognomonic for AIDS in both HIV and simian immunodeficiency virus (SIV) infections. It occurs early, is massive at mucosal sites, and is not entirely reverted by antiretroviral therapy (ART), particularly if initiated when T-cell functions are compromised. HIV/SIV infect and kill activated CCR5-expressing memory and effector CD4+ T-cells from the intestinal lamina propria. Acute CD4+ T-cell depletion is substantial in progressive, nonprogressive and controlled infections. Clinical outcome is predicted by the mucosal CD4+ T-cell recovery during chronic infection, with no recovery occurring in rapid progressors, and partial, transient recovery, the degree of which depends on the virus control, in normal and long-term progressors. The nonprogressive infection of African nonhuman primate SIV hosts is characterized by partial mucosal CD4+ T-cell restoration, despite high viral replication. Complete, albeit very slow, recovery of mucosal CD4+ T-cells occurs in controllers. Early ART does not prevent acute mucosal CD4+ T-cell depletion, yet it greatly improves their restoration, sometimes to preinfection levels. Comparative studies of the different models of SIV infection support a critical role of immune activation/inflammation (IA/INFL), in addition to viral replication, in CD4+ T-cell depletion, with immune restoration occurring only when these parameters are kept at bay. CD4+ T-cell depletion is persistent, and the recovery is very slow, even when both the virus and IA/INFL are completely controlled. Nevertheless, partial mucosal CD4+ T-cell recovery is sufficient for a healthy life in natural hosts. Cell death and loss of CD4+ T-cell subsets critical for gut health contribute to mucosal inflammation and enteropathy, which weaken the mucosal barrier, leading to microbial translocation, a major driver of IA/INFL. In turn, IA/INFL trigger CD4+ T-cells to become either viral targets or apoptotic, fueling their loss. CD4+ T-cell depletion also drives opportunistic infections, cancers, and comorbidities. It is thus critical to preserve CD4+ T cells (through early ART) during HIV/SIV infection. Even in early-treated subjects, residual IA/INFL can persist, preventing/delaying CD4+ T-cell restoration. New therapeutic strategies limiting mucosal pathology, microbial translocation and IA/INFL, to improve CD4+ T-cell recovery and the overall HIV prognosis are needed, and SIV models are extensively used to this goal.

NaïVe T Cell Depletion of PBSC Grafts Results in Very Low Rates of Chronic Gvhd and High Survival

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 668-668
Author(s):  
Marie Bleakley ◽  
Ted A. Gooley ◽  
Barbara Hilzinger ◽  
Stanley R Riddell ◽  
Warren D Shlomchik
Keyword(s):  
T Cells ◽  
T Cell ◽  
Acute Leukemia ◽  
Chronic Gvhd ◽  
Hematopoietic Cell ◽  
T Cell Subsets ◽  
Cell Depletion ◽  
Effector Memory ◽  
Phase Ii Trials ◽  
T Cell Depletion

Abstract Background Graft-versus-host disease (GVHD) frequently causes morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT) as a result of organ damage and infections. In HLA-identical HCT, GVHD results from recognition by donor T cells of minor histocompatibility (H) antigens on recipient tissues. Complete T cell depletion (TCD) of donor hematopoietic cell products is more effective than pharmacologic immunosuppression for preventing GVHD, but is complicated by delayed immune reconstitution and consequent life-threatening infections.Approaches to HCT which preferentially deplete the T cells that primarily cause GVHD and preserve pathogen-specific T cells may improve HCT outcomes. Mature CD3+ CD8+ and CD3+ CD4+ T cells can be classified into CD45RA+ CD62L+ naïve (TN) and CD45RO+ memory (TM) subsets, the latter of which includes effector memory (TEM) and central memory (TCM) cells. Murine studies in which allogeneic TCD bone marrow (BM) is transplanted with purified T cells from individual T cell subsets to irradiated minor H antigen disparate recipients have demonstrated that the most severe GVHD results from transplanting T cells of the TN subset. Purified TCM causes mild GVHD and TEM do not cause detectable GVHD and can transfer immunity to pathogens.In vitro studies have similarly demonstrated that human donor CD8+ T cells specific for recipient minor H antigens are found predominantly within the TN cell subset, suggesting selective TN cell depletion may alter the GVHD incidence and/or severity in human HCT. Methods and results We developed an effective process for engineering human peripheral blood stem cell (PBSC) grafts that depletes CD45RA+ TN cells and retains CD34+ stem cells and functional CD45RO+ TM cells specific for a broad range of opportunistic pathogens (Bleakley BBMT 2014). We are conducting clinical trials to evaluate the selective depletion of TN cells from HLA-matched allogeneic PBSC grafts for the prevention of GVHD in patients with acute leukemia, the first of which has been published (Bleakley JCI 2015, N=35). Seventy patients have now been treated on three consecutive phase II trials. The median age was 34 years (1-56 years), 56% of patients had a diagnosis of ALL, 46% had previously relapsed or had detectable disease (MRD or relapse) at the time of HCT, and 23% had unrelated donor (URD) grafts. Intensive myeloablative, TBI-containing (13.2Gy) conditioning was used for 63 patients, whilst 7 patients received a medium intensity 'midi' preparative regimen, including 4Gy of TBI. The TN-depletion procedure was successfully performed on URD PBSC products shipped overnight from donor centers throughout the US, as well as on MRD PBSC collected at our centers. Reliable engraftment with high-level donor chimerism was observed in recipients of 'midi' as well as intensive myeloablative conditioning. The 2-year estimates of overall survival, disease-free survival, survival free of relapse and chronic GVHD (CRFS) and survival free of relapse, grade II-IV acute GVHD, and chronic GVHD (GRFS) are 79%, 73%, 69% and 63% respectively. Median follow-up among survivors is 26 months. The frequency and severity of chronic GVHD is remarkably low (5%) compared to historical rates of 40-60% chronic GVHD in HLA-matched PBSC transplantation with conventional calcineurin inhibitor-based immunosuppression. Relapse and non-relapse mortality (NRM) are acceptably low at 19% and 8%, respectively. No NRM occurred in patients <40 years. Updated results will be presented. Conclusions The outcomes of recipients of TN-depleted PBSC grafts compare very favorably to published results of HCT for patients with acute leukemia. For example, the 69% incidence of CRFS at 2 years in TN-depleted recipients compares with reported 2-year GRFS rates of 37% and 17% in recipients of allogeneic PBSC from HLA-matched related donors with or without ATG (Kroger et al. NEJM 2016). Our results suggest that TN-depletion of PBSC grafts may reduce the risk of chronic GVHD without negatively impacting other important HCT outcomes. Disclosures Riddell: Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Cell Medica: Consultancy, Honoraria; Adaptive Biotechnologies: Consultancy, Honoraria.

Memory and naive-like regulatory CD4+ T cells expand during HIV-2 infection in direct association with CD4+ T-cell depletion irrespectively of viremia

AIDS ◽  
2011 ◽  
Vol 25 (16) ◽  
pp. 1961-1970 ◽  
Author(s):  
Russell B. Foxall ◽  
Adriana S. Albuquerque ◽  
Rui S. Soares ◽  
António P. Baptista ◽  
Rita Cavaleiro ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Cd4 T Cell ◽  
Cell Depletion ◽  
T Cell Depletion ◽  
Direct Association

T cell depletion in HIV-1 infection: how CD4+ T cells go out of stock

10.1038/79724 ◽  
2000 ◽  
Vol 1 (4) ◽  
pp. 285-289 ◽  
Author(s):  
Mette D. Hazenberg ◽  
Dörte Hamann ◽  
Hanneke Schuitemaker ◽  
Frank Miedema
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Cell Depletion ◽  
T Cell Depletion ◽  
Hiv 1

scholarly journals Characteristics of Plasmacytoid Dendritic Cell and CD4+ T Cell in HIV Elite Controllers

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jean-Philippe Herbeuval ◽  
Nikaïa Smith ◽  
Jacques Thèze
Keyword(s):  
T Cells ◽  
Viral Load ◽  
T Cell ◽  
Cd4 T Cells ◽  
Plasmacytoid Dendritic Cell ◽  
Cd4 T Cell ◽  
Cell Depletion ◽  
T Cell Depletion ◽  
Hiv Controllers ◽  
Hiv 1

Despite variability, the majority of HIV-1-infected individuals progress to AIDS characterized by high viral load and massive CD4+ T-cell depletion. However, there is a subset of HIV-1-positive individuals that does not progress and spontaneously maintains an undetectable viral load. This infrequent patient population is defined as HIV-1 controllers (HIV controllers), and represents less than 1% of HIV-1-infected patients. HIV-1-specific CD4+ T cells and the pool of central memory CD4+ T cells are also preserved despite immune activation due to HIV-1 infection. The majority of HIV controllers are also defined by the absence of massive CD4+ T-cell depletion, even after 10 years of infection. However, the mechanisms involved in protection against HIV-1 disease progression have not been elucidated yet. Controllers represent a heterogeneous population; we describe in this paper some common characteristics concerning innate immune response and CD4+ T cells of HIV controllers.

scholarly journals Interaction between HIV and Mycobacterium tuberculosis: HIV-1-induced CD4 T-cell depletion and the development of active tuberculosis

2017 ◽  
Author(s):  
Christof Geldmacher ◽  
Michael Hoelscher ◽  
Alimuddin Zumla
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Hiv Infection ◽  
Cd4 T Cells ◽  
Incidence Rates ◽  
Cd4 T Cell ◽  
Cell Depletion ◽  
Effector Memory ◽  
T Cell Depletion

Purpose of Review: HIV infection is the main driver of the HIV/tuberculosis (TB) syndemic in southern Africa since the early 1990s, when HIV infection rates started to increase exponentially and TB incidence rates quadruplet simultaneously. Here, we discuss pathogenic mechanisms of HIV-induced CD4 T-cell depletion and their potential impact on immune control of Mycobacterium tuberculosis. Recent Findings: Depletion of effector memory CD4 T cells from the air-tissue interphase, their dysfunctional regeneration and the preferential depletion of MTB-specific CD4 T cells from circulation and from the air-tissue interphase might be key factors for the increased susceptibility to develop active TB after HIV infection. Summary: Early initiation of antiretroviral therapy or the development of an efficacious HIV vaccine would be the best options to reduce morbidity and mortality associated with the HIV/TB syndemic. © Lippincott Williams &amp; Wilkins.

Low Incidence of Post-Transplant EBV-Related Disease After Alemtuzumab-Mediated T Cell Depletion Is Explained by the Differential Susceptibility to Alemtuzumab of B Cells and Protective CD8 and CD4 T Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2330-2330
Author(s):  
Constantijn J.M. Halkes ◽  
Inge Jedema ◽  
Judith Olde Wolbers ◽  
Esther M van Egmond ◽  
Peter A. Von Dem Borne ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Depletion ◽  
T Cell Depletion

Abstract Abstract 2330 In vivo T cell depletion with anti-thymocyte globulin (ATG) or alemtuzumab (anti-CD52) before reduced intensity allogeneic stem cell transplantation (alloSCT) in combination with in vitro T cell depletion with alemtuzumab reduces the risk of GVHD. Detectable levels of circulating antibodies are present up to several months after the alloSCT, leading to a delayed immune reconstitution which is associated with an increased incidence of opportunistic infections and early relapses. Prior to 2007, combined in vitro (Alemtuzumab 20 mg added “to the bag”) and in vivo T cell depletion with horse-derived ATG (h-ATG) resulted in good engraftment without GVHD in the absence of GVHD prophylaxis after reduced intensity alloSCT using conditioning with fludarabine and busulphan. Due to the unavailability of h-ATG, rabbit-derived ATG (r-ATG) 10–14 mg/kg was introduced in the conditioning regimen in 2007. Strikingly, in this cohort of patients, early EBV reactivation and EBV-associated post-transplantation lymphoproliferative disease (PTLD) was observed in 10 out of 18 patients at a median time of 6 weeks after alloSCT (range 5 to 11 weeks) in the absence of GVHD or immunosuppressive treatment. Analysis of T and B cell recovery early after transplantation revealed preferential depletion of T cells as compared to B cells, thereby allowing unrestricted proliferation of EBV infected B cells. Due to this unacceptable high incidence of EBV-related complications, in the conditioning regimen r-ATG was replaced by low dose alemtuzumab (15 mg i.v. day -4 and -3) in 2008. In this cohort of 60 patients, only 2 patients experienced transient EBV reactivation during the first 3 months after alloSCT and one patient developed an EBV-associated lymphoma 4 weeks after alloSCT. To investigate the mechanisms underlying the low incidence of EBV reactivation using alemtuzumab for T cell depletion, we studied the in vivo and in vitro effects of alemtuzumab on different lymphocyte subsets. First, lineage-specific reconstitution was studied in 20 patients from the alemtuzumab cohort with known CD52 negative diseases (11 AML and 9 multiple myeloma) to exclude the confounding effect of antibody absorption by malignant cells. Whereas at 3 weeks after alloSCT detectable numbers of circulating NK cells and T cells were observed (medians 71 (range 6–378), and 12 (range 1–1164)E6/L, respectively), no circulating B cells could be detected (median 0, range 0–1 E6/L). At 6 weeks after alloSCT, NK and T cell numbers further increased (medians 212 (52-813), and 130 (range 25–1509)E6/L, respectively), whereas B cell numbers still remained low in the majority of patients (median 15, range 0–813E6/L). In all patients, T cells were detectable before the appearance of circulating B cells. Furthermore, the expression of CD52 and the sensitivity to alemtuzumab-mediated complement-dependent cell lysis (CDC) of B cells, T cells and NK cells was measured in vitro. The highest CD52 expression was observed on B cells (mean fluorescence intensity (MFI) 120), resulting in 95% lysis after incubation with 10ug/mL alemtuzumab and rabbit complement. NK cells showed a significantly lower CD52 expression (MFI 41), which was also reflected by a lower susceptibility to alemtuzumab-mediated CDC (62% lysis). Interestingly, differential expression of CD52 was observed on CD4 and CD8 T cells (MFI 120 and 101, respectively). Cytotoxicity analysis revealed relative protection of CD8 compared to CD4 T cells against alemtuzumab-mediated CDC, resulting in 52% and 90% lysis, respectively. Based on these results, we investigated in detail the presence and phenotype of the CD4 and CD8 subsets and EBV-specific CD8 T cells using tetramer staining at 6 weeks after alloSCT. In accordance with the in-vitro expression and susceptibility data, circulating CD52+ CD8 T cells including EBV-specific T cells were detectable. Interestingly, the majority of circulating CD4 T cells (64-93%, n=4) lacked CD52 expression, explaining their capacity to persist in the presence of alemtuzumab. We conclude that in vivo and in vitro T cell depletion with alemtuzumab is associated with a relatively low risk of EBV-associated PTLD because of efficient B cell depletion and persistent EBV immunity allowed by the relative insusceptibility for alemtuzumab of CD8 T cells and the development of CD52 negative escape variants of CD4 T cells. Disclosures: No relevant conflicts of interest to declare.

In Vivo T Cell Depletion Using Rabbit Derived ATG Leads to An Increased EBV-PTLD Risk Due to An Induced Imbalance Between B and T Cell Recovery Which Is Not Seen After Horse Derived ATG or Alemtuzumab

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1979-1979 ◽  
Author(s):  
C.J.M. Halkes ◽  
J.H.F. Falkenburg ◽  
H.M. van Egmond ◽  
J. Olde Wolbers ◽  
C.W.J. Starrenburg ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Cd8 T Cells ◽  
Cell Depletion ◽  
Cell Recovery ◽  
Post Transplantation ◽  
T Cell Depletion

Abstract Abstract 1979 Control of replication of endogenous viruses like CMV and EBV is fully dependent on CMV or EBV specific T cells after allogeneic stem cell transplantation (alloSCT). In the absence of specific CD8 T cell control, proliferation of EBV infected B cells can lead to post transplantation lymphoproliferative disease (PTLD). In an initial cohort of patients treated with horse derived anti thymocyte globulin (h-ATG), no early PTLD was observed. However, due to unavailability in Europe, h-ATG had to be replaced by rabbit derived ATG (r-ATG), leading to an unacceptable high incidence of EBV-PTLD (26% during first 3 months after alloSCT). Replacement of r-ATG by alemtuzumab (ALT) significantly reduced the incidence of EBV-PTLD (3 months incidence of EBV-PTLD 2%). To determine the immunological basis of these findings we performed a detailed analysis of immune reconstitution in these three cohorts of transplanted patients. The first cohort (41 patients) received h-ATG (Lymphoglobulin) 10 mg/kg/day for 4 days. The second cohort (19 patients) received r-ATG (Thymoglobulin) 2.0 or 3.5 mg/kg/day for 4 days and the third cohort (60 patients) received ALT, 15 mg/day for 2 days. All grafts consisted of PBSC to which 20 mg of ALT was added for in vitro T cell depletion. All patients received a fludarabin and busulphan based conditioning regimen. No standard post transplantation immunosuppressive treatment was given. In the r-ATG cohort, early EBV-PTLD occurred after a median of 7 weeks (range 4–12 weeks) post alloSCT. Three r-ATG treated patients died while high levels of circulating EBV-DNA were present (> log 4.0 copies/mL). Incidence of CMV disease was not significantly different in the three cohorts (5%, 6% and 0%, respectively). In contrast to the other 2 cohorts, immune reconstitution in the r-ATG cohort was characterized by an imbalance between recovery of B cells and CD8 T cells. Already 3 weeks after alloSCT, the majority (67%) of r-ATG patients showed a more rapid reconstitution of B cells than CD8 T cells, leading to B cells outnumbering CD8 T cells. This was seen in only a small minority of patients after h-ATG and ALT (17% and 6%, respectively, p<0.01 versus r-ATG). Because rapid recovery of T cells in the alemtuzumab patients was frequently found in the presence of circulating ALT (mean concentration 0.43 μg/mL and 0.12 μg/mL after 3 and 6 weeks, respectively), the phenotype of circulating CD4 and CD8 T cells at 6 weeks after ALT was analyzed. The majority of circulating CD8 and CD4 T cells lacked CD52 expression (56% (range 0–99%) and 81% (range 0–93%), respectively). Using tetramer staining, cytotoxicity assays and analysis of cytokine production, we demonstrated the presence of functional CD52 negative as well as CD52 positive CMV and EBV specific CD8 T cells. Based on FLAER negativity, it was demonstrated that the CD52 negative T cells are GPI anchor deficient, representing a PNH-like clone escaping ALT induced cell lysis. Because almost half of the circulating CD8 T cells were CD52 positive, we examined expression of CD52 and the in-vitro sensitivity to ALT-mediated complement-dependent cell lysis (CDC) of B cells, CD4 and CD8 T cells of healthy donors. The highest CD52 expression was observed on B cells (mean fluorescence intensity (MFI) 120), resulting in 95% lysis after incubation with ALT and complement. Differential expression of CD52 was observed on CD4 and CD8 T cells, MFI 120 and 101 respectively, resulting in relative protection of CD52 positive CD8 compared to CD4 T cells against ALT-mediated CDC (52% and 90% lysis). We conclude that the high incidence of EBV-PTLD after in-vivo T cell depletion with r-ATG is caused by an induced imbalance between B and T cell recovery, which is not seen after h-ATG or ALT. In-vivo T cell depletion with ALT is associated with a relatively low risk of EBV disease because of efficient B cell depletion and persistent EBV immunity due to the relative insusceptibility for ALT of CD8 T cells and the development of functional CD52 negative escape variants of CD4 and CD8 T cells. Disclosures: Off Label Use: Alemtuzumab and Anti Thymocyte Globulin used for in vivo T cell depletion prior to allogeneic stem cell transplantation.

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