Reconstitution of T-cell receptor repertoire diversity following T-cell depleted allogeneic bone marrow transplantation is related to hematopoietic chimerism

CDR3 spectratyping was used to analyze the complexity of the T-cell repertoire and to define the mechanisms and kinetics of the reconstitution of T-cell immunity after allogeneic bone marrow transplantation (BMT). This method, which is based on polymerase chain reaction amplification of all CDR3 regions using the T-cell receptor (TCR) Vbeta genes, was used to examine serial samples of peripheral blood lymphocytes from 11 adult patients with chronic myelogenous leukemia (CML) who underwent T-cell-depleted allogeneic BMT. In contrast to 10 normal donors who display highly diverse and polyclonal spectratypes, patient samples before and early after BMT revealed markedly skewed repertoires, consisting of absent, monoclonal, or oligoclonal profiles for the majority of Vbeta subfamilies. To quantify changes in TCR repertoire over time, we established an 8-point scoring system for each Vbeta subfamily. The mean complexity score for patient samples before transplant (130.8) was significantly lower than that for normal donors (183; P = 0. 0007). TCR repertoire complexity was abnormal in all patients at 3 months after BMT (mean score = 87). Normalization of repertoire began in 4 patients at 6 months after BMT, but the majority of patients continued to display abnormal repertoires for up to 3 years after BMT. To determine whether the reconstituted T-cell repertoire was derived from the donor or recipient, unique microsatellite loci were examined to establish chimeric status. At 3 months after BMT, 7 patients demonstrated mixed chimerism; 4 had complete donor hematopoiesis (CDH). CDH strongly correlated with likelihood of restoration of T-cell repertoire complexity (P = 0.003). In contrast, patients who demonstrated persistence of recipient hematopoiesis failed to reconstitute a diverse TCR repertoire. These findings suggest that the reconstitution of a normal T-cell repertoire from T-cell progenitors in adults is influenced by interactions between recipient and donor hematopoietic cells. (Blood. 2000;95: 352-359)

Long-term follow-up of autologous bone marrow transplantation in patients with relapsed follicular lymphoma

We report the results of high-dose chemoradiotherapy and anti-B-cell monoclonal antibody-purged autologous bone marrow transplantation (ABMT) in patients with relapsed indolent follicular lymphoma. Between March 1985 and May 1995, 153 patients underwent ABMT using a uniform ablative regimen with cyclophosphamide and total body irradiation and bone marrow (BM) purging. All patients received multiple chemotherapy regimens before ABMT. At BM harvest, only 30% of patients were in complete remission, and overt BM infiltration was present in 47%. The disease-free survival (DFS) and overall survival (OS) are estimated to be 42% and 66% at 8 years, respectively. Patients whose BM was negative by polymerase chain reaction (PCR) for bcl2/IgH rearrangement after purging experienced longer freedom from recurrence than those whose BM remained PCR positive (P <.0001). Continued PCR negativity in follow-up BM samples was also strongly predictive of continued complete remission (CR). The 12-year survival from diagnosis for these 153 patients is 69%. Considering that the median survival from diagnosis and first recurrence of patients with advanced follicular lymphoma are 8 and 5 years, respectively, our results provide evidence that myeloablative therapy and ABMT may prolong overall survival.

Outcome in patients with myelodysplastic syndrome after autologous bone marrow transplantation for non-Hodgkin's lymphoma

PURPOSE

The absolute risk of myelodysplastic syndrome (MDS) after autologous bone marrow transplant (ABMT) for non-Hodgkin's lymphoma (NHL) exceeds 5% in several reported series. We report the outcome of a large cohort of patients who developed MDS after ABMT for NHL.

PATIENTS AND METHODS

Between December 1982 and December 1997, 552 patients underwent ABMT for NHL, with a uniform ablative regimen of cyclophosphamide and total body irradiation followed by reinfusion of obtained marrow purged with monoclonal antibodies. MDS was strictly defined, using the French-American-British classification system, as requiring bone marrow dysplasia in at least two cell lines, with associated unexplained persistent cytopenias.

RESULTS

Forty-one patients developed MDS at a median of 47 months after ABMT. The incidence of MDS was 7.4%, and actuarial incidence at 10 years is 19.8%, without evidence of a plateau. Patients who developed MDS received significantly fewer numbers of cells reinfused per kilogram at ABMT (P =.0003). Karyotypes were performed on bone marrow samples of 33 patients, and 29 patients had either del(7) or complex abnormalities. The median survival from diagnosis of MDS was 9.4 months. The International Prognostic Scoring System for MDS failed to predict outcome in these patients. Thirteen patients underwent allogeneic BMT as treatment for MDS, and all have died of BMT-related complications (11 patients) or relapse (two patients), with a median survival of only 1.8 months.

CONCLUSION

Long-term follow-up demonstrates a high incidence of MDS after ABMT for NHL. The prognosis for these patients is uniformly poor, and novel treatment strategies are needed for this fatal disorder.

Autologous bone marrow transplantation after histologic transformation of indolent B cell malignancies

The role of high-dose therapy and autologous stem cell transplantation in diffuse large B cell lymphoma (DLBCL) after transformation is controversial. We have retrospectively analyzed patients with chemosensitive disease and a history of follicular lymphoma or chronic lymphocytic leukemia/small lymphocytic lymphoma who underwent high-dose chemoradiotherapy and bone marrow transplantation (BMT) with anti-B cell monoclonal antibody-purged autologous marrow for DLBCL. Between December 1982 and August 1997, 27 patients underwent autologous BMT using a uniform ablative regimen with cyclophosphamide, total-body irradiation, and bone marrow purging. All patients received multiple chemotherapy regimens before autologous BMT. At bone marrow (BM) harvest, only 44% of patients were in complete remission, and overt BM infiltration was present in 37%. After cyclophosphamide and total-body irradiation, no treatment-related deaths were seen. Eleven of the 27 patients relapsed, and four patients developed myelodysplasia/acute myelogenous leukemia. In seven patients in whom pathologic studies were available after relapse, the histology remained DLBCL. Twelve patients remained alive and in complete remission with a median follow-up of 36 months (range 10-132). The disease-free survival and overall survival are estimated to be 46% (90% confidence interval 28-64) and 58% (40-76) at 5 years, respectively. Patients whose disease underwent histologic transformation within 18 months of their initial diagnosis of indolent lymphoma had significantly better overall survival. Selected patients with histologic transformation, particularly those whose transformation occurs early in the course of their disease and who remain chemosensitive, may experience prolonged survival after autoBMT.

CD69 is a stimulatory receptor for natural killer cell and its cytotoxic effect is blocked by CD94 inhibitory receptor

CD69 is a differentiation antigen expressed shortly after activation on T lymphocytes and other cells of haematopoietic origin, including natural killer (NK) cells. The function of CD69 on T lymphocytes acting as a costimulatory molecule in proliferation and lymphokine secretion is well established. NK cells express CD69 after activation by different stimuli such as phorbol 12-myristate 13-acetate (PMA), interleukin (IL)-2, IL-12, interferon-alpha (IFN-alpha) or anti-CD16 monoclonal antibodies (mAbs). However, although it has been shown that CD69 triggers NK-cell-mediated cytolytic activity, its effect on other NK-cell functions has not been studied. Furthermore, the possible interaction of CD69 triggering with other C-lectin type inhibitory receptors is not known. Thus, the objective of this work is to determine whether CD69-mediated NK cytotoxicity can be regulated by CD94 inhibitory receptor and the role of CD69 on other NK-cell functions different of cytotoxicity. The results show that CD69-mediated NK cytotoxicity can be abrogated by CD94 stimulation in NK cells expressing the CD94 inhibitory form of the receptor, indicating that CD94 regulates the cytotoxic events initiated by a wide variety of NK activatory receptors. We also show that anti-CD69 mAbs, not only triggered NK cytotoxicity, but also induce NK-cell proliferation, CD25 and intracellular adhesion molecule-1 (ICAM-1) expression, TNF-alpha production and Ca2+ mobilization in preactivated NK cells. These results suggest that CD69 plays a crucial role in NK-cell function contributing to sustain NK-cell activation, as it has been previously demonstrated in T cells.

The functional synergy between IL-12 and IL-2 involves p38 mitogen-activated protein kinase and is associated with the augmentation of STAT serine phosphorylation

IL-12 and IL-2 can stimulate mitogen- or CD3-activated T cells to proliferate, produce IFN-gamma, and kill tumor cells. The magnitude of these functional responses is greatly augmented when T cells are activated by the combination of IL-12 and IL-2. Although peripheral blood T cells are largely unresponsive to these cytokines without prior activation, a small subset of CD8+ T cells (CD8+CD18bright) is strongly activated by the combination of IL-12 and IL-2. In this report we show that the functional synergy between IL-12 and IL-2 in CD8+CD18bright T cells correlates with the activation of the stress kinases, p38 mitogen-activated protein (MAP) kinase and stress-activated protein kinase (SAPK)/Jun N-terminal kinase, but not with the activation of the extracellular signal-regulated kinases. The functional synergy between IL-2 and IL-12 is also associated with a prominent increase in STAT1 and STAT3 serine phosphorylation over that observed with IL-12 or IL-2 alone. By contrast, STAT tyrosine phosphorylation is not augmented over that seen with either cytokine alone. A specific inhibitor of p38 MAP kinase completely inhibits the serine phosphorylation of STAT1 and STAT3 induced by IL-12 and IL-2 and abrogates the functional synergy between IL-12 and IL-2 without affecting STAT tyrosine phosphorylation. This suggests that p38 MAP kinase may play an important role in regulating STAT serine phosphorylation in response to the combination of IL-12 and IL-2. Furthermore, these findings indicate that the optimal activation of T cells by IL-12 and IL-2 may depend on an interaction between the p38 MAP kinase and Janus kinase/STAT signaling pathways.

Fludarabine-induced immunosuppression is associated with inhibition of STAT1 signaling

Fludarabine is a nucleoside analog used in the treatment of hematologic malignancies that can induce severe and prolonged immunosuppression. Although it can be incorporated into the DNA of dividing cells, fludarabine is also a potent inhibitor of cells with a low growth fraction, thus it must have other mechanisms of action. STAT1, which is activated in response to many lymphocyte-activating cytokines including the interferons, is essential for cell-mediated immunity, as the absence of this protein is associated with prominent defects in the ability to control viral infections. Here we show that fludarabine, but not the immunosuppressant cyclosporine A, inhibits the cytokine-induced activation of STAT1 and STAT1-dependent gene transcription in normal resting or activated lymphocytes. Fludarabine caused a specific depletion of STAT1 protein (and mRNA) but not of other STATs. This loss of STAT1 was also seen in cells from patients treated with fludarabine in vivo. Brief exposure to fludarabine led to a sustained loss of STAT1, analogous to the prolonged period of immunosuppression induced by exposure to the drug in vivo. Thus, STAT1 may be a useful target in the development of new immunosuppressive and antineoplastic agents.

Comparative outcomes of T-cell-depleted and non-T-cell-depleted allogeneic bone marrow transplantation for chronic myelogenous leukemia: impact of donor lymphocyte infusion

PURPOSE

Donor lymphocyte infusion (DLI) can restore complete remission in patients with chronic myelogenous leukemia (CML) who have relapsed after T-cell-depleted (TCD) allogeneic bone marrow transplantation (BMT). The existence of salvage treatment for patients with DLI after TCD allogeneic BMT prompted an evaluation of overall outcome after CD6+ -TCD allogeneic BMT for patients treated during the time when DLI has been available.

PATIENTS AND METHODS

We performed a retrospective analysis of outcomes of 46 patients who underwent TCD allogeneic BMT for stable-phase CML and compared these outcomes with those of 40 patients who underwent non-TCD allogeneic BMT. All subjects were patients at one of two neighboring institutions during a period when DLI was available. All patients received marrow from HLA-identical sibling donors, underwent similar myeloablative regimens, and had similar pretreatment characteristics.

RESULTS

After BMT, the TCD group had a lower incidence of grade 2 to 4 acute (15% v 37%, P = .026) and chronic graft-versus-host disease (GVHD) (18% v 42%, P = .024) than did the non-TCD group. The 1-year treatment-related mortality rates for the TCD group and the non-TCD group were 13% and 29%, respectively (P = .07). The estimated 3-year probability of relapse (cytogenetic or hematologic) was higher for patients in the TCD group than for patients in the non-TCD group (62% v 24%, P = .0003). Twenty-three patients (20 in the TCD group and three in the non-TCD group) received and were assessable for response to DLI. After DLI, 17 of 20 patients in the TCD group and two of three patients in the non-TCD group achieved complete remission. Donor lymphocyte infusion induced GVHD in nine of 23 patients. Thirty (65%) of 46 patients in the TCD group and 27 (69%) of 39 assessable patients in the non-TCD group remained alive without evidence of disease. The estimated 3-year overall survival rates were similar for the TCD group and the non-TCD group (72% v 68%, respectively; P = .38). At last follow-up, there was no difference in the overall prevalence of GVHD or the proportion of patients requiring immunosuppressive agents between groups.

CONCLUSION

These results suggest that the combination of T-cell depletion and post-BMT DLI is a viable treatment option for patients undergoing allogeneic BMT for CML and should be prospectively compared with traditional forms of GVHD prophylaxis.

PTEN is inversely correlated with the cell survival factor Akt/PKB and is inactivated via multiple mechanismsin haematological malignancies

PTEN is a novel tumour suppressor gene that encodes a dual-specificity phosphatase with homology to adhesion molecules tensin and auxillin. It recently has been suggested that PTEN dephosphorylates phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3, 4,5)P3], which mediates growth factor-induced activation of intracellular signalling, in particular through the serine-threonine kinase Akt, a known cell survival-promoting factor. PTEN has been mapped to 10q23.3, a region disrupted in several human tumours including haematological malignancies. We have analysed PTEN in a series of primary acute leukaemias and non-Hodgkin's lymphomas (NHLs) as well as in cell lines. We have also examined whether a correlation could be found between PTEN and Akt levels in these samples. We show here that the majority of cell lines studied carries PTEN abnormalities. At the structural level, we found mutations and hemizygous deletions in 40% of these cell lines, while a smaller number of primary haematological malignancies, in particular NHLs, carries PTEN mutations. Moreover, one-third of the cell lines had low PTEN transcript levels, and 60% of these samples had low or absent PTEN protein, which could not be attributed to gene silencing by hypermethylation. In addition, we found that PTEN and phosphorylated Akt levels are inversely correlated in the large majority of the examined samples. These findings suggest that PTEN plays a role in the pathogenesis of haematological malignancies and that it might be inactivated through a wider range of mechanisms than initially considered. The finding that PTEN levels inversely correlate with phosphorylated Akt supports the hypothesis that PTEN regulates PtdIns(3,4,5)P3and suggests a role for PTEN in apoptosis.

Immunological effects of interleukin 12 administered by bolus intravenous injection to patients with cancer

The immunological effects of recombinant human interleukin 12 (rhIL-12) administration were examined during the conduct of a Phase I clinical trial. Forty patients with advanced cancer received bolus i.v. injections of rhIL-12 in doses ranging between 3 and 1000 ng/kg. Dose-dependent increases in serum IFN-gamma levels were seen during rhIL-12 therapy. Significant lymphopenia was observed 24 h after single i.v. injections of rhIL-12 at each dose level. The degree of lymphopenia was dose dependent, and a plateau effect was seen with rhIL-12 doses of 100 ng/kg and higher. Lymphocyte counts reached nadir levels at approximately 10 h after rhIL-12 injection and returned to baseline within 14 days postinjection. Rebound lymphocytosis, as seen after interleukin 2 therapy, was not observed after recovery from rhIL-12-induced lymphopenia. rhIL-12-induced lymphopenia involved all major lymphocyte subsets, although natural killer (NK) cell numbers were the most profoundly affected, and CD4 T-cell numbers were the least affected. CD2, LFA-1, and CD56 were transiently up-regulated on the surface of NK cells exposed to rhIL-12 in vivo. Peripheral blood mononuclear cells obtained from cancer patients before rhIL-12 therapy exhibited defective NK cell cytotoxicity and T-cell-proliferative responses. Peripheral blood mononuclear cells obtained after lymphocyte recovery following the administration of a single 500 ng/kg dose of rhIL-12 displayed augmented NK cell cytolytic activity in four of four patients tested and enhanced T-cell proliferation in three of four patients tested. These studies confirm that doses of rhIL-12 resulting in significant immunological activity can be administered with acceptable toxicity to cancer patients. Furthermore, rhIL-12 therapy can reverse defects in NK cell and T-cell function that are associated with advanced cancer in humans.

IL-2 induces STAT4 activation in primary NK cells and NK cell lines, but not in T cells

IL-2 exerts potent but distinct functional effects on two critical cell populations of the immune system, T cells and NK cells. Whereas IL-2 leads to proliferation in both cell types, it enhances cytotoxicity primarily in NK cells. In both T cells and NK cells, IL-2 induces the activation of STAT1, STAT3, and STAT5. Given this similarity in intracellular signaling, the mechanism underlying the distinct response to IL-2 in T cells and NK cells is not clear. In this study, we show that in primary NK cells and NK cell lines, in addition to the activation of STAT1 and STAT5, IL-2 induces tyrosine phosphorylation of STAT4, a STAT previously reported to be activated only in response to IL-12 and IFN-alpha. This activation of STAT4 in response to IL-2 is not due to the autocrine production of IL-12 or IFN-alpha. STAT4 activated in response to IL-2 is able to bind to a STAT-binding DNA sequence, suggesting that in NK cells IL-2 is capable of activating target genes through phosphorylation of STAT4. IL-2 induces the activation of Jak2 uniquely in NK cells, which may underlie the ability of IL-2 to activate STAT4 only in these cells. Although the activation of STAT4 in response to IL-2 occurs in primary resting and activated NK cells, it does not occur in primary resting T cells or mitogen-activated T cells. The unique activation of the STAT4-signaling pathway in NK cells may underlie the distinct functional effect of IL-2 on this cell population.

Efficacy and costs of granulocyte colony-stimulating factor in allogeneic T-cell depleted bone marrow transplantation

Hematopoietic growth factors have shown clinical benefits in patients undergoing chemotherapy and stem cell transplantation, but few studies have been performed to assess whether the benefits are worth the costs. We reviewed 196 patients undergoing T-cell depleted related donor bone marrow transplantation (BMT) between 1990 and 1996 to assess the effect of growth factor use on time to engraftment and costs of hospitalization. Beginning in 1994, based on encouraging results in autologous transplantation, patients (n = 81) were treated with granulocyte colony-stimulating factor (G-CSF) starting at day +1 after marrow infusion until engraftment. Between January 1, 1990 and January 1, 1994, patients (n = 115) did not receive growth factor. CD6 depletion of donor marrow was the only form of prophylaxis against graft-versus-host disease (GVHD). Despite receiving a lower stem cell dose (P = .004), the group receiving G-CSF had a decreased time to engraftment (20 days v 12 days, P < .0001) and time from marrow infusion to discharge (23 days v 17 days, P < .0001). In multivariate modeling, the use of G-CSF was the most significant factor predicting time to engraftment and discharge. Incidence of grades II-IV GVHD, early mortality, percentage of patients who engrafted, and relapse rates did not differ between the groups. Inpatient charges during the first 50 days after marrow infusion (including readmissions) were available on 110 patients and were converted to costs using departmental ratios of costs of charges. Median costs were significantly lower in the group receiving G-CSF ($80,600 v $84,000, P = .0373). Thus, use of G-CSF in this setting allows earlier hospital discharge with lower costs.

Regulatory dysfunction of the interleukin-2 receptor during HIV infection and the impact of triple combination therapy

The interleukin-2 (IL-2)/IL-2 receptor (IL-2R) system is the main regulatory determinant of T cell reactivity. Although it is well known that IL-2 secretion is impaired during HIV infection, up to now IL-2R expression has not been extensively studied in HIV-infected patients despite the use of IL-2 in clinical therapy trials. We show here that IL-2R expression in HIV patients with high viral load (group 1 in the study) is greatly enhanced on B lymphocytes, CD8 T lymphocytes, and monocytes, but not on CD4 T lymphocytes, compared with noninfected individuals. Paradoxically, this modified IL-2R expression does not lead to increased IL-2 responsiveness, except for B lymphocytes. In patients receiving triple combination therapy (TCT, two reverse transcriptase inhibitors and one protease inhibitor) that has triggered a drastic reduction in plasma viral load and an increase in CD4 counts (group 2 patients), IL-2R expression is significantly lower than in group 1 patients. Moreover, cells involved in cellular immunity and CD4 T lymphocytes have the capacity to respond to IL-2 after TCT. These results allow us to anticipate a beneficial role of IL-2 immunotherapy in combination with TCT.

Characterization of a novel subset of CD8(+) T cells that expands in patients receiving interleukin-12

IL-12 has significant antitumor activity in mice that may be mediated by CD8(+) T cells. We show in this report that repeated subcutaneous injections of IL-12 in patients with cancer resulted in the selective expansion of a subset of peripheral blood CD8(+) T cells. This T cell subset expressed high levels of CD18 and upregulated IL-12 receptor expression after IL-12 treatment in vivo. In normal subjects, these CD3(+)CD8(+)CD18(bright) T cells expressed IL-12 and IL-2 receptors and adhesion/costimulatory molecules to a greater degree than other CD8(+) and CD4(+) T cells. They appeared morphologically as large granular lymphocytes, although they did not express NK cell markers such as CD56. In addition, CD8(+)CD18(bright) T cells were almost exclusively T cell receptor (TCR) alphabeta+, and exhibited a TCR Vbeta repertoire that was strikingly oligoclonal, whereas the Vbeta repertoire of CD18(dim) T cells was polyclonal. Although CD8+CD18(bright) T cells demonstrated little functional responsiveness to IL-12 or IL-2 alone in vitro, they responded to the combination of IL-12+IL-2 with strong IFN-gamma production and proliferation and enhanced non-MHC-restricted cytolytic activity. In contrast, CD18(dim) T cells were not activated by IL-12 or IL-2, alone or in combination. These findings demonstrate that CD8+CD18(bright) T cells are a unique population of peripheral blood lymphocytes with features of both memory and effector cells that are capable of TCR-independent activation through combined stimulation with IL-12+IL-2. As this activation results in IFN-gamma production and enhanced cytolytic activity, these T cells may play a role in innate as well as acquired immunity to tumors and infectious pathogens. Additional studies will be necessary to determine whether CD8+CD18(bright) T cells mediate the antitumor effect of IL-12 or IL-2 administered to cancer patients, and if so, whether maximal activation of these T cells with the combination of IL-12+IL-2 in vivo can augment the clinical effectiveness of these cytokines.

TAL1 expression does not occur in the majority of T-ALL blasts

The TAL1 gene is disrupted by translocation or deletion (tal(d)) in up to 30% of T-cell acute lymphoblastic leukaemia (T-ALL), leading to aberrant transcriptional activation, as a SIL-TAL1 fused transcript in tal(d). It has been suggested that TAL1 transcription occurs in approximately 50% of a T-ALLs without apparent rearrangement. SIL-TAL1 was positive in 15/60 (25%) of T-ALL, whereas wild-type TAL1 transcripts were detected in all 13 SIL-TAL1 and in 19/43 (44%) T-ALL without SIL-TAL1. To investigate the cellular origin of TAL1 we exploited the fact that GATA1 and TAL1 are co-ordinately expressed in non-lymphoid haemopoietic cells, whereas only the latter is found in T-ALL. GATA1 was detected in 10/23 (43%) TAL1-negative T-ALLs but in 17/19 (89%) 'unexplained' TAL1-positive cases, suggesting a common non-lymphoid cellular origin. Immunocytochemical analysis with a TAL1-specific monoclonal antibody showed nuclear expression in the blasts of 10/34 (29%) cases, including 8/10 SIL-TAL1+ and two RT-PCR TAL1+, SIL-TAL1- cases. In the remaining cases TAL1 expression was restricted to a minor population (< 5%) of larger, strongly TAL1-positive cells which comprised erythroid cells, CD34+ CD3- precursors and an unidentified TAL1+ CD45- population which morphologically resembled monocytes/macrophages. We therefore suggest that appropriate diagnostic evaluation of T-ALL should include molecular detection of SIL-TAL1 transcripts and in situ immunocytochemical detection of TAL1 protein expression by leukaemic blasts. This approach will enable accurate analysis of the prognostic significance of TAL1 deregulation in T-ALL.

CD6+ T cell-depleted allogeneic bone marrow transplantation for non-Hodgkin's lymphoma

For patients with non-Hodgkin's lymphoma (NHL) undergoing blood or bone marrow transplantation (BMT), the use of autologous grafts has often been preferred to that of allogeneic stem cells because of a significantly lower incidence of non-relapse mortality. If complications associated with allo-BMT could be minimized without compromising efficacy, then it might become a preferred strategy for certain subsets of patients. In this report, we describe the toxicity and long-term efficacy of T cell-depleted allogeneic BMT using anti-CD6 monoclonal antibody and complement alone to reduce the risk of GVHD and its sequelae. Twenty-two patients, aged 18-60 years, with high (n = 10), intermediate (n = 9), or low (n = 3) grade NHL underwent HLA-identical allogeneic BMT from siblings. Patients had either relapsed after at least one remission or never achieved a full remission with chemotherapy. Twenty patients had a history of marrow involvement. Bone marrow was depleted of CD6+ T cells with T12 monoclonal antibody and complement as the sole form of GVHD prophylaxis. Stable hematopoietic engraftment occurred in all 22 patients. Four patients developed grade 2 and 1 patient grade 3 GVHD (23% grades 2-4 GVHD). Chronic GVHD has occurred in three patients. Treatment-related mortality was very low. Only one patient died while in remission. Thirteen patients are alive and free of disease with a median follow-up of 30 months. Estimated event-free and overall survivals are 54 and 59%, respectively. CD6 allogeneic marrow transplantation is associated with a low risk of transplant-related complications and may offer advantages for certain patients with recurrent NHL felt to be at high risk for relapse after autologous transplantation.

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 x 10(8) CD4(+) 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 x 10(8) CD4 cells/kg developed GVHD compared with 6 of 11 patients (55%) who received >/=1.0 x 10(8) 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.

IL-15 is produced by a subset of human melanomas, and is involved in the regulation of markers of melanoma progression through juxtacrine loops

IL-15 is a novel cytokine active through the IL-2R/betagamma. Since several human melanoma cell lines display functional IL-2Rs, we studied the IL-15/melanoma cells interactions. Ten out of 17 melanoma cell lines express the IL-15 transcript and four of them express levels of IL-15 mRNA similar to those detected in control activated monocytes. Nine out of ten cell lines also express two transcripts for the IL-15R alpha originated by the alternative splicing of exon'3'. Two melanoma cell lines, MELP and MELREO, derived from patients with rapidly progressive primary melanomas, co-express the two IL-15 transcripts, originated by alternative splicing of exon 'A'. Intracellular IL-15 protein was only detected in these two cells lines and it is mainly retained in the Endoplasmic Reticulum (ER). However, a small amount of IL-15 is also found in the Golgi apparatus and in the early endosomes, suggesting production and intercellular trafficking of endogenous IL-15 protein. Nevertheless, no biologically active IL-15 could be detected in the supernatant of all melanoma cells. The anti IL-15 blocking mAb M111 causes the up regulation of HLA Class I in dense MELP and MELREO cultures. These data suggest that IL-15 is probably active through juxtacrine loops negatively controlling HLA Class I molecules expression. These data offer, for the first time, a likely explanation to the controversial issue of IL-15 secretion and constitute a natural model for understanding IL-15 routing. Moreover, we identify a subset of melanoma cells producing IL-15, possibly involved in tumor escape mechanisms.

Altered interleukin-12 responsiveness in Th1 and Th2 cells is associated with the differential activation of STAT5 and STAT1

T-cell activation in response to interleukin-12 (IL-12) is mediated through signaling events that include the tyrosine phosphorylation of STAT4. IL-12 responsiveness and the ability of IL-12 to activate STAT4 is different in T cells induced to differentiate into a Th1 or Th2 phenotype. In this report, we show that STAT5, STAT1alpha, and STAT1beta, in addition to STAT4, are tyrosine phosphorylated in response to IL-12 in phytohemagglutinin (PHA)-activated human T cells. To understand how the activation of these STATs contributes to T-cell IL-12 responsiveness, we analyzed the IL-12-induced activation of STAT5 and STAT1 in T cells stimulated to undergo Th1 or Th2 differentiation. The IL-12-induced tyrosine phosphorylation of STAT5 and STAT1, but not STAT4, is augmented in T cells activated into Th1 cells with PHA + interferon-gamma (IFN-gamma) compared with T cells activated with PHA alone. STAT5 DNA binding induced by IL-12 is also augmented in T cells activated with PHA + IFN-gamma compared with T cells activated with PHA alone, whereas STAT4 DNA binding is not increased. In contrast, the IL-12-induced activation of these STATs is inhibited in T cells activated into Th2 cells with PHA + IL-4. The enhancement of IL-12 signaling by IFN-gamma is not a direct effect of IFN-gamma on T cells, but rather is mediated by IL-12 that is produced by antigen-presenting cells in response to IFN-gamma. This positive autoregulatory effect of IL-12 on the activation of select STATs correlates with an increase in T-cell IFN-gamma production in response to IL-12. These findings suggest that the activation of STAT5 and STAT1 may augment select STAT4-dependent functional responses to IL-12 in Th1 cells.

Participation of the CD94 receptor complex in costimulation of human natural killer cells

Optimal proliferation and expansion of human NK cells require mitogenic cytokines together with cell contact-dependent co-stimulation. Production of mAb that can modulate human NK cell proliferation yielded NKH3, which recognizes the CD94 Ag. NKH3 immunoprecipitates contain approximately 70-kDa heterodimeric complexes consisting of a approximately 25-kDa glycoprotein and approximately 40- to 45-kDa molecules. Analysis by two-dimensional isoelectric focusing/SDS-PAGE suggests that several different 40- to 45-kDa species are present in the CD94 receptor complex in human NK cells. NKH3 reacted with essentially all resting NK cells, although CD94 is expressed at higher levels on the CD56(bright) (i.e., high level of CD56) CD16(dim/neg) (i.e., low level of or absent CD16) subpopulation than on the more abundant CD56(dim)CD16(bright) NK cell subset. Moreover, the Z199 mAb, which appears to recognize NKG2-A species that can form heterodimers with CD94, stained virtually all CD56(bright) NK cells, but only a subset of CD56(dim) NK cells. Ligation of CD94 augmented the proliferation of CD56(bright) NK cells in response to IL-2 or IL-15 by as much as 10-fold. Secretion of IFN-gamma by CD56(bright) NK cells stimulated with IL-2 or IL-15 was also enhanced up to 10-fold after CD94 ligation. CD94 mAb did not consistently costimulate proliferation of or IFN-gamma production by CD56(dim) NK cells cultured with IL-2 or IL-15. In contrast, irradiated K562 cells costimulated proliferation of both CD56(bright) and CD56(dim) NK cells. These results indicate that CD56(bright) and CD56(dim) NK cells can be costimulated through different receptors, which may allow these distinct NK cell subsets to be independently regulated in vivo.

Further analysis of interleukin-2 receptor subunit expression on the different human peripheral blood mononuclear cell subsets

We have investigated the expression of the three components of the interleukin-2 receptor (IL-2Ralpha, IL-2Rbeta, and IL-2Rgamma) on the surface of the various peripheral blood mononuclear cell (PBMC) subsets by flow cytometry analysis. The PBMC were immediately isolated (ficoll) from blood collected on heparin as anticoagulant. The three IL-2R components are absent or only marginally detectable on CD4 T lymphocytes. No expression of the IL-2R chains is found for the B lymphocytes. In most donors, the three chains are not detectable on CD8 T lymphocytes, but for a few of them, IL-2Rbeta or IL-2Rgamma are clearly expressed. CD56 high (IL-2Ralpha+) and CD56 low (IL-2Ralpha-) natural killer (NK) cells express IL-2Rbeta, but not IL-2Rgamma. IL-2Rgamma is expressed by monocytes of all donors although with variable intensity. When blood is collected on other anticoagulants or when cells are isolated 1 day after collection, IL-2Ralpha, IL-2Rbeta, and IL-2Rgamma are largely expressed on the surface of most PBMC. This observation provides a possible explanation for divergent data previously reported on IL-2R expression. Finally, we show that IL-2Rgamma, which is not detectable on the cell surface of lymphocytes, is nevertheless expressed and stored as an intracellular component. This result is in agreement with the constitutive expression of the IL-2Rgamma gene and suggests a specific regulatory mechanism for IL-2Rgamma membrane translocation.

High-dose chemoradiotherapy and anti-B-cell monoclonal antibody-purged autologous bone marrow transplantation in mantle-cell lymphoma: no evidence for long-term remission

PURPOSE

The role for high-dose therapy and autologous stem-cell transplantation in mantle-cell lymphoma (MCL) is unknown. We retrospectively analyzed patients with chemosensitive disease who underwent high-dose chemoradiotherapy and anti-B-cell monoclonal antibody-purged autologous bone marrow transplantation (ABMT) for MCL in first remission, as well as following relapse from conventional therapy.

PATIENTS AND METHODS

Between August 1985 and April 1996, 28 patients underwent ABMT using a uniform ablative regimen with cyclophosphamide and total-body irradiation (TBI) and a bone marrow-purging regimen. Re-review of original tissue demonstrated that all patients had morphologic, phenotypic, and genotypic characteristics of MCL. MCL was the original diagnosis in 21 patients, whereas seven patients had a prior diagnosis of diffuse small cleaved-cell lymphoma.

RESULTS

Twenty patients received multiple regimens before ABMT, while eight underwent ABMT in first complete remission (CR)/partial remission (PR) following CHOP induction. At bone marrow harvest, only 18% of patients were in CR and overt BM infiltration was present in 57%. Following cyclophosphamide/TBI, no treatment-related deaths were seen. Nineteen of 28 patients have relapsed at a median time of 21 months (range, 3 to 70). Of eight patients transplanted in first CR/PR, five have relapsed. Nine patients are in continuous CR with a median follow-up time of 24 months (range, 10 to 135). Disease-free survival (DFS) and overall survival (OS) are estimated to be 31% and 62% at 4 years, respectively.

CONCLUSION

ABMT using cyclophosphamide/TBI conditioning may at best be effective in only a small fraction of patients with relapsed MCL. The lack of plateau with a median follow-up time of 24 months suggests cure may not be achievable. The role of this therapy in patients in first remission requires more study using better induction therapy to enhance the CR rate before ABMT.

B lymphocytes from patients with chronic lymphocytic leukemia contain signal transducer and activator of transcription (STAT) 1 and STAT3 constitutively phosphorylated on serine residues

To explore the pathogenesis of chronic lymphocytic leukemia (CLL), we examined whether phosphorylation of one or more signal transducer and activator of transcription (STAT) factors was abnormal in cells from CLL patients. No constitutive tyrosine phosphorylation was detected on any STAT in CLL cells. To assess the phosphorylation of serine residues of STAT1 and STAT3 in CLL cells, we raised antibodies that specifically recognize the form of STAT1 phosphorylated on ser-727 and the form of STAT3 phosphorylated on ser-727. We found that in 100% of patients with CLL (n = 32), STAT1 and STAT3 were constitutively phosphorylated on serine. This was in contrast to normal peripheral blood B lymphocytes or CD5+) B cells isolated from tonsils, in which this phosphorylation was absent. Serine phosphorylation of STAT1 and STAT3 was seen occasionally in other leukemias, but it was a universal finding only in CLL. The serine phosphorylation of these STATs was a continuous process, as incubation of CLL cells with the kinase inhibitor H7 led to the dephosphorylation of these serine residues. The STAT serine kinase in CLL cells has not been identified, and appears to be neither mitogen-activated protein kinase nor pp70(s6k). In summary, the constitutive serine phosphorylation of STAT1 and STAT3 is present in all CLL samples tested to date, although the physiologic significance of this modification remains to be determined.

Cyclophosphamide, doxorubicin, vincristine, prednisone dose intensification with granulocyte colony-stimulating factor markedly depletes stem cell reserve for autologous bone marrow transplantation

Hematopoietic growth factors allow dose escalation of chemotherapy. This approach may potentially reduce the quality and quantity of hematopoietic stem cells. The capacity of stem cells recovered after dose intensification to support myeloablative therapy is unknown. In patients with previously untreated advanced follicular lymphoma, trilineage hematopoietic engraftment was compared in two sequential trials of induction therapy (standard dose cyclophosphamide, doxorubicin, vincristine, prednisone [CHOP] without growth factors or dose intensification CHOP supported by granulocyte colony-stimulating factor [G-CSF ]) followed by identical myeloablative therapy and autologous stem cell support. Neutrophil, platelet, and red blood cell (RBC) engraftment were compared on days 100, 180, and 360 after stem cell reinfusion. Despite similar patient characteristics including reinfusion of comparable numbers of marrow mononuclear cells, after stem cell transplantation, a highly significant prolongation of neutrophil and platelet engraftment was seen in patients who received high dose CHOP and G-CSF in comparison to standard dose CHOP. These findings suggest that dose intensified chemotherapy and G-CSF recruited stem cells into a proliferative phase and that G-CSF allowed retreatment at a time when stem cells were susceptible to damage by cytotoxic therapy. Such inadequate hematologic engraftment after myeloablative therapy might be avoided by either shortening the time that growth factor support is administered, lengthening the interval between cycles, or attempting to repetitively harvest additional stem cells either from the marrow or peripheral blood. Therefore, intensification of chemotherapy with growth factor support must be used with caution if stem cells are to be used to support myeloablative therapy.