ALBERT

Description: We tested the hypothesis that estrogen acutely stimulates constitutive nitric oxide synthase activity in human granulocytes by acting on a cell surface estrogen receptor (ER). The release of nitric oxide was measured in real time with an amperometric probe. Exposure of granulocytes to 17β-estradiol stimulated NO release within seconds in a concentration-dependent manner. The NO release was also stimulated by 17β-estradiol conjugated to bovine serum albumin (E2-BSA), which suggests mediation by a cell surface receptor. Tamoxifen, an ER inhibitor, antagonized the action of both 17β-estradiol and E2-BSA, whereas ICI 182,780, an inhibitor of the nuclear ER, had no effect. Using dual emission microfluorometry in a calcium-free medium, the 17β-estradiol–stimulated release of NO from granulocytes was shown to be dependent on intracellular calcium ([Ca2+]i) transients in a tamoxifen-sensitive process. Exposure to BAPTA-AM (1,2bis-(-aminophenoxy)ethans-N,N,N′,N′-tetraacetic acid tetra(acetoxyymethyl) ester), a [Ca2+]i chelator, reduced [Ca2+]i in response to E2-BSA, and depleting [Ca2+]i stores abolished the effect of 17β-estradiol on NO release. Confocal photomicrographs using E2-BSA–FITC (fluorescein isothiocyanate) revealed cell membrane reactivity. Estrogen-stimulated NO release had an immunosuppressive effect, and it initiated granulocyte rounding and loss of adherence in a tamoxifen-sensitive manner. Finally, using reverse transcriptase–polymerase chain reaction, human neutrophil granulocytes expressed ER but not ERβ, suggesting that ER may be the membrane receptor for 17β-estradiol. The study demonstrated that a physiological dose of estrogen down-regulates granulocyte activity by acutely stimulating NO release via the activation of a cell surface ER which is coupled to increases in [Ca2+]i.

Description: The curative potential of allo-SCT for malignancies derives from the progressive reconstitution of the immune system and the development of effective anti-tumor immunity, but GVHD and disease relapse remain considerable obstacles to improvement in overall outcomes. Because in recipients target antigens are persisting, donor-derived T-cell responses may be expected to lead to the accumulation of a sizable proportion of differentiated T-cells, as happens following infection with persisting pathogens. A few cross-sectional studies have pointed to the preponderance of certain memory T-cell subsets associated with chronic GVHD (cGVHD), but the subset identified differed between studies. Inasmuch as qualitative T-cell recovery takes months to years to complete and there is substantial variability in time to development of GVHD or relapse, serial analysis might be more suitable to unveil early changes in T-cell subset composition attributable to transplantation-related events. From October 2003 on, 55 pts who underwent an allo-SCT after myeloablative conditioning were monitored prospectively in terms of clinical post-graft complications, including graft rejection, infections, GVHD and relapse. Blood samples were obtained on days 30±2, 60±3, 90±5, 180±10 and 365±15 post-transplant. Naive (CD45RA+CCR7+), central memory (TCM, CD45RAnegCCR7+), effector memory (TEM, CD45RAnegCCR7neg), and terminally differentiated effector (TTD, CD45RA+CCR7neg) were enumerated within the CD4+ and CD8+ pools, and the percentage of cells coexpressing CD28 was calculated within each eight subsets. The degree of donor-derived T-cell chimerism was assessed by real time PCR (sensitivity ≤ 1%). Median follow-up was 733 d (404–1251). Dynamics of CD4+ and CD8+ naive, TCM, TEM, and TTD were similar between the pts who developed cGVHD (n=15) and those who did not and between pts who relapsed and those who did not. However, costaining to detect CD28 demonstrated contrasting differences between cGVHD and relapse. At day 30, pts who subsequently relapsed (n=17) had elevated percentages of cells keeping CD28 expression within CD8+ T-cell subsets (TCM, p=.001; TCM, p=.021; and TTD, p=.007). Conversely, pts who subsequently developed cGVHD (n=15; only one relapsed) had diminished percentages of CD28+ cells within the two CD8+CCR7+ subsets at day 30 (p=.002 and p=.034, respectively). Loss of CD28 expression is known to be a hallmark of CMV infection but multivariate analysis ruled out, however, a confounding effect of CMV. Adjusted hazard ratios were 0.10 (95% CI, 0.01-0.76; p=.026) and 5.56 (95% CI, 1.16-25.00; p=.032) with CD28neg cells 16.7% of all CD8+ TCM at day 30 for relapse and cGVHD, respectively. Furthermore, pts with relapse had more often mixed chimerism at day 30 while those with cGVHD had more often full-donor chimerism (p=.042 and p=.023, respectively). CONCLUSION: This prospective study is the first to associate an early contrasting change in CD8+CD28neg T-cells with the risk of relapse and cGVHD after a myeloablative conditioning. Determination at day 30 of the proportions of CD8+ T-cell subsets expressing CD28 and of the level of T-cell chimerism could assist in predicting risk of relapse and cGVHD and help build an algorithm for the management of immunosuppressive treatment.

Description: Peripheral G-CSF-mobilized blood stem cells (PBSC), use as alternative to marrow stem cells (MSC), is associated with enhanced engraftment and accelerated hematopoietic recovery after allo-SCT. However, despite an increased number of donor T cells infused, the incidence of acute GVHD with PBSC appears to remain identical or less than with MSC. Recent works on the heterogeneity of the human CD4+ and CD8+ T cells have individualized 4 subsets: namely, naive (CCR7+CD45RA+), central memory (TCM, CCR7+CD45RA−), effector memory (TEM, CCR7−CD45RA−), and CD45RA+ effector memory cells (TEMRA, CCR7−CD45RA+). To our knowledge, the T cell subsets proportions in MSC and PBCSP grafts remain unknown. The impact of the infused T cell subsets on patients’ outcome is still to be investigated. Between September 2003 and July 2004, 25 consecutive hematopoietic allo-SCT (12 MSC and 13 PBSC) were considered for this study. Multiple combinations of immunophenotyping analysis were used to prospectively examine immune parameters related to graft as well as to early reconstitution. Early post-transplant complications including acute GVHD, relapse and infections were assessed. As expected, T cells subsets, B cells and NK cells numbers were significantly higher in PBSC grafts (versus MSC). However, proportions of CD4+ and CD8+ T-cell subsets were comparable in the 2 types of graft and similar to normal values observed with peripheral blood of healthy adults. Table below summarize the distribution of T cell subsets within T CD4+ and T CD8+ in the two types of graft. The incidence of acute GVHD was significantly higher in pts receiving 〉 5% of CD8+ TEM cells among infused CD8+ cells (p

Description: Allogeneic stem cell transplantation has become standard therapy for haematological malignancies through the positive immunologic graft-versus-leukaemia effect. Initial immune recovery relies on peripheral expansion of infused T-cells which switch to a memory-like phenotype. This study prospectively investigated whether changes in subset composition precedes late complications after myeloablative HLA-matched transplantation. Of 80 recipients, 51 experienced neither early infection nor acute graft-versus-host disease (GVHD), of whom 18 were still free of clinical complication throughout 395 – 1564 days of follow-up. Compared with this complication-free subgroup, patients who developed chronic GVHD as the only event recovered similar numbers of circulating T-cells with predominance of CD8+ T-cells lacking CC-chemokine receptor-7 and CD28 expression. Conversely, poor CD8+ T-cell recovery with diminished numbers of CD28neg CD8+ T-cells (~1/4th of that of relapse-free patients) preceded occurrence of relapse. In multivariate analysis, lower CD28neg CD8+ T-cell counts by day 60 were associated with greater risk of subsequent relapse (HR 0.33; 95% CI 0.14 - 0.76; P = 0.01). Enumeration of CD28neg CD8+ T-cells in patients without early clinical complication could assist in predicting risk of relapse and help build an algorithm for accelerating the immune recovery by reducing the immunosuppressive regimen and considering the introduction of prophylactic donor lymphocyte infusions.

Description: Abstract 4702 Background: Allogeneic stem cell transplantation provides donor-derived mature T cells which are involved in post-transplant immune reactions including engraftment, graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) activity, and thus play a major role in determining clinical outcome. In a prior clinical study, we showed that receiving a high percentage of CD4+CCR7+ T cells that includes naive and central memory (CM) subsets, was correlated with increased incidence and severity of acute GVHD. In a recent update of our results on 126 patients, we confirmed our previous results with a particular impact of CD4+ naive subset on acute GVHD development. The aim of the present study was to investigate in vitro the alloreactive response of CD4+CCR7+CD45RA+ naïve T cells and CD4+CCR7+CD45RAneg central memory T cells in HLA-A, -B, -C, -DRB1 and -DQB1 allele matched setting (so called 10/10 match) Materials and methods: The alloreactivity was investigated by mixed lymphocyte dendritic cell reaction using five HLA-identical healthy male and female sibling pairs to include at least a H-Y mismatch. Stimulators were mature dendritic cells (derived from monocytes of the male sibling) co-cultured with each one of the three highly purified CD4+ T cell subsets (naive, central memory and effector memory) from the female sibling. Alloreactive response was assessed by 3H thymidine incorporation at day 5, and functionally at day 4, 6 and 10 by IFN-gamma ELISpot and measurement of Th1/Th2/Th17 cytokines in co-culture supernatants. Results: Four out of five sibling pairs developed an alloreactive response to mHAs. Maximal proliferation was supported by the CCR7+CD45RA+ naive CD4+ T cells with proliferation indices from 1.75 to 3.85. This proliferation was accompanied by a functional differentiation: only naive CD4+ T cells were able to produce significant amounts of IL-6, TNF-alpha and IFN-gamma at day 6 and day 10 (120 to 174 IFN-gamma spots at day 10). Conclusion: This study demonstrates the superior capacity of naive CD4+ T cells to mount a primary alloreactive response as compared to central memory T cells. Their proliferative response associated with a pro-inflammatory differentiation makes naive CD4+ T cells potential acute GVHD inducers. These in vitro results confirm what we have observed in clinical studies and may also lend support to approaches of selective T cell depletion for GVHD prevention. Disclosures: No relevant conflicts of interest to declare.

Description: We tested the hypothesis that estrogen acutely stimulates constitutive nitric oxide synthase activity in human granulocytes by acting on a cell surface estrogen receptor (ER). The release of nitric oxide was measured in real time with an amperometric probe. Exposure of granulocytes to 17β-estradiol stimulated NO release within seconds in a concentration-dependent manner. The NO release was also stimulated by 17β-estradiol conjugated to bovine serum albumin (E2-BSA), which suggests mediation by a cell surface receptor. Tamoxifen, an ER inhibitor, antagonized the action of both 17β-estradiol and E2-BSA, whereas ICI 182,780, an inhibitor of the nuclear ER, had no effect. Using dual emission microfluorometry in a calcium-free medium, the 17β-estradiol–stimulated release of NO from granulocytes was shown to be dependent on intracellular calcium ([Ca2+]i) transients in a tamoxifen-sensitive process. Exposure to BAPTA-AM (1,2bis-(-aminophenoxy)ethans-N,N,N′,N′-tetraacetic acid tetra(acetoxyymethyl) ester), a [Ca2+]i chelator, reduced [Ca2+]i in response to E2-BSA, and depleting [Ca2+]i stores abolished the effect of 17β-estradiol on NO release. Confocal photomicrographs using E2-BSA–FITC (fluorescein isothiocyanate) revealed cell membrane reactivity. Estrogen-stimulated NO release had an immunosuppressive effect, and it initiated granulocyte rounding and loss of adherence in a tamoxifen-sensitive manner. Finally, using reverse transcriptase–polymerase chain reaction, human neutrophil granulocytes expressed ER but not ERβ, suggesting that ER may be the membrane receptor for 17β-estradiol. The study demonstrated that a physiological dose of estrogen down-regulates granulocyte activity by acutely stimulating NO release via the activation of a cell surface ER which is coupled to increases in [Ca2+]i.

Description: Abstract 1251 Allogeneic stem cell transplantation (allo-SCT) following reduced-intensity conditioning (RIC) represents a concrete alternative to standard myeloablative conditioning. Even though, immune reactions observed after RIC (i.e. GVHD, GVL.), tend to be similar to those observed after myeloablative regimens, there are many differences in their clinical features, timing of onset, and their impact on patient's outcome. The homeostatic cytokines, IL-7 and IL-15 are essential driving forces for homeostatic peripheral expansion of T lymphocytes that are responsible, not only for GVL effect but also for GVHD which is a major complication post-transplant. Almost all mature T-cells express the specific IL-7 receptor alpha chain (IL-7Rα). Memory CD8+ T cells and natural killer (NK) cells express the highest levels of IL-2/15Rβ chain, making these cells particularly responsive to IL-15. Few studies have associated GVHD with systemic levels of either IL-7 or IL-15 but only one concerned patients undergoing RIC. However, patients reported in the latter study, had received prior induction chemotherapy and experienced profound lymphopenia after conditioning, leading to levels of IL-7 and IL-15 comparable to those usually observed after myeloablative regimens. In addition, the issue of IL-7R and IL-2/15Rβ expression has not been addressed yet in allo-SCT patients. This prompted us to prospectively investigate plasma levels of IL-7 and IL-15, T-cell recovery, and the expression levels of IL-7Rα and IL-2/15Rβ chains in patients undergoing RIC. Forty-five consecutive patients who underwent fully HLA-matched allo-SCT after RIC were included. Plasma levels of IL-7 and IL-15 were determined by ELISA at enrolment, on day 0 before grafting, every three days during the first month, and then on days 60 and 90. CD3+, CD4+, CD8+ T-cells and NK cells counts at day 30, 60 and 90 post-graft were obtained by flow-cytometry-based technique. Expression of IL-7Rα and IL-2/15Rβ (% and MFI) was evaluated on each subsets of naïve and memory T-cells, categorized according to their expression of CD45RA and CCR7 markers. Kinetic courses of plasma IL-7 levels, evolved inversely to lymphocyte counts up to day 30 (R= -.529; P= .001). The higher plasma IL-7 levels were associated with the lower MFI of IL-7Rα on CD4+ naïve, CD8+ naïve, CD4+ central memory, and CD8+ central memory T-cells (p=.005, .01,

Description: Abstract 3227 Background: Umbilical cord blood (CB) transplantation is known to be associated with delayed and defective immune reconstitution, in part because recent thymic emigrants (RTEs), the most common subset among CB T cells, have limited intrinsic survival. Interleukin-7 (Il-7) has been reported to increase the initial recovery of the graft-derived T-cells compartment. The aim of this study was to investigate CB-derived T-cell survival and to define a minimal effective dose of recombinant human IL-7 (rIL-7), considering that in addition to its anti-apoptotic effect, IL-7 may enhance immune reactions that occur in the host, including uncontrolled acute GVHD. Methods: Fifteen CB were obtained immediately after normal-term delivery, using the same procedure as for CB banking. T cells were isolated within 12 hours by negative magnetic bead sorting and cultured for 2 weeks either directly or after being frozen in order to recapitulate clinical procedures. Unstimulated T cell cultures were conducted in parallel in medium (RPMI supplemented with 10% normal AB serum) alone or supplemented with a range of rIL-7concentrations added either only once at day 0 (100 to 1000 pg/mL) or every day (10 to 100 pg/mL). Cell viability was assessed by flow cytometric scatter analysis and staining with 3,3'-dihexyloxacarbocyanine iodide [DiOC6(3)] and propidium iodide. Results: In basic culture conditions, the majority of T cells had died over 2 weeks, but there was a marked heterogeneity in cell survival, as proportions of viable T cells varied from 2% to 50% (median 15%) at day 6 of culture. Interestingly, the same intrinsic characteristics of survival were observed in T cells that underwent beforehand a freezing-thawing procedure. In cultures supplemented with rIL-7, we confirmed the efficacy of rIL-7 in maintaining CB T cell survival. A minimal dose of 20 to 50 pg/mL of IL-7 added daily was sufficient to induce the prolonged survival of CB T cells, with more than 95% of viable cells at day 6. Noteworthy, these concentrations allowed prolonged survival of CD T cells without inducing any cell proliferation, as shown by the absence of CFSE dilution. Similar results were observed comparing CB cells that had been frozen or not. Conclusion: Repeated low-doses of rIL-7 are required to preserve the survival capacity of CB T cells without inducing their proliferation. These results could represent a framework for clinical studies aiming at improving T cell reconstitution following allogeneic CB transplantation. Repeated administration of low-doses of rIL-7 might be especially useful in patients with low serum levels of IL-7 after conditioning. Disclosures: No relevant conflicts of interest to declare.

Description: In a fully molecular HLA-matched setting, the outcome of allogeneic stem-cell transplantation (allo-SCT) can be affected by mismatches in minor histocompatibility antigens (mHAs) that might impact on the risk of graft-versus-host (GvH) and graft-versus-leukemia (GvL) effects. The association between mHA disparities and outcome was investigated in 96 consecutive patients who underwent myeloablative HLA-matched allo-SCT (from 69 HLA-identical siblings and 27 HLA-matched unrelated donors, all typed and matched at both allelic levels for HLA-A, -B, -Cw, -DRB1, and -DQB1 loci) for standard-risk hematological malignancy (AML n = 41; ALL n = 29; MDS n = 12; CML n = 8; others n = 6). All patients but 9 received bone marrow graft. Allelic mHAg typing was performed by PCR with sequence-specific primers for 9 autosomally encoded mHA and H-Y (PCR-SSP; Spierings et al. PLoS ONE. 2006 Dec 20; 1:e42). The distribution of autosomal mHAs among donor and recipients conformed to the expected frequencies for this population. As expected, the prevalence of mHAg mismatches was higher in unrelated compared to related recipient/donor pairs (p 〈 .003). In univariate analysis, patients who received a graft with more than 2 mHAg mismatches developed more often grade II-IV acute GvH disease (p = .01; HR=2.92 [1.28–6.64]). In multivariate analysis, HA2 mismatch emerged as an independent determinant of acute GvH disease (p = .05; HR = .42). When only mismatches in the GvL/GvH direction were considered, mismatch for HA-1, that is expressed mainly by the hematopoietic system, tended to influence the incidence of both acute and chronic GvH disease (p = .06; HR=1.47 [0.97–2.21] and p = .049; HR = 1.45 [1.00–2.10], respectively) but also to confer a reduced risk of relapse (p = .07; HR = .58 [0.32–1.05]). Mismatch for HA-8, that has a broad tissue distribution, emerged as an independent risk factor of grade II-IV acute GvH disease (p = .02; HR = 1.77 [1.08–2.89]). This study confirms the impact of mHAg mismatches on patients’ outcome after fully HLA-matched allo-SCT and highlights both the cumulative effect of mHAg disparities on outcome and the distinctive contribution of individual mHAs on GvH versus GvL effects of allo-SCT.