Suppression of graft-versus-host disease and amplification of graft-versus-tumor effects by activated natural killer cells after allogeneic bone marrow transplantation.

Bone marrow transplantation (BMT) is currently used for the treatment of a variety of neoplastic diseases. However, significant obstacles limiting the efficacy of allogeneic BMT are the occurrence of graft-versus-host disease (GvHD) and tumor relapse. Natural killer (NK) cells exert a variety of immunologic and homoeostatic functions. We examined whether adoptive transfer of activated NK cells of donor type would prevent GvHD after allogeneic BMT in mice. Lethally irradiated C57BL/6 (H-2(b)) mice, were transplanted with MHC incompatible BALB/c (H-2(d)) bone marrow cells and spleen cells and rapidly succumbed to acute GvHD. In contrast, mice that also received activated NK cells of donor type exhibited significant increases in survival. In determining the mechanism by which the NK cells prevented GvHD, mice were concurrently treated with a neutralizing antibodies to the immunosuppressive cytokine TGFbeta. Anti-TGFbeta completely abrogated the protective effects of the activated donor NK cells indicating that TGFbeta plays an important role in the prevention of GvHD by NK cells. We then examined whether activated NK cells of donor type after allogeneic BMT would induce graft-versus-tumor (GvT) effects without GvHD in mice bearing a murine colon adenocarcinoma (MCA-38). 10 d after receiving the tumor, in which the mice had demonstrable lung metastases, recipients received an allogeneic BMT with or without activated NK cells. Administration of activated NK cells resulted in significant GvT effects after allogeneic BMT as evidenced by increases in median survival and fewer lung metastasis. No evidence of GVHD was detected compared with recipients receiving spleen cells alone which also developed fewer lung metastases but in which all had succumbed to GVHD. Thus, our findings suggest that adoptive immunotherapy using activated donor NK cells combined with allogeneic BMT inhibits GvHD and promotes GvT in advanced tumor-bearing mice. These results also suggest that GvT and GvHD can be dissociable phenomena.

Immunologic and hematopoietic effects of CD40 stimulation after syngeneic bone marrow transplantation in mice.

CD40 is a molecule present on multiple cell types including B lymphocyte lineage cells. CD40 has been shown to play an important role in B cell differentiation and activation in vitro, although little is known concerning the effects of CD40 stimulation in vivo. We therefore examined the effects of CD40 stimulation in mice using a syngeneic bone marrow transplantation (BMT) model in an effort to augment B cell recovery after high dose therapy with hematopoietic reconstitution. After the BMT, mice were treated with or without 2-6 microg of a soluble recombinant murine CD40 ligand (srmCD40L) given intraperitoneally twice a week. A significant increase in B cell progenitors (B220+/ surface IgM-) was observed in the bone marrow of mice receiving the srmCD40L. The treated recipients also demonstrated improved B-cell function with increases in total serum immunoglobulin and increased splenic mitogen responsiveness to LPS being noted. Additionally, srmCD40L treatment promoted secondary lymphoid organ repopulation, accelerating germinal center formation in the lymph nodes. Total B cell numbers in the periphery were not significantly affected even with continuous srmCD40L administration. Lymphocytes obtained from mice treated with the ligand also had increases in T cell mitogen and anti-CD3 mAb responsiveness and acquired the capability to produce IL-4. Surprisingly, treatment with srmCD40L also produced hematopoietic effects in mice, resulting in an increase of BM and splenic hematopoietic progenitor cells in the mice after BMT. Treatment with srmCD40L significantly increased granulocyte and platelet recovery in the peripheral blood. Incubation of BMC with srmCD40L in vitro also resulted in increased progenitor proliferation, demonstrating that the hematopoietic effects of the ligand may be direct. Thus, stimulation of CD40 by its ligand may be beneficial in accelerating both immune and hematopoietic recovery in the setting of bone marrow transplantation.

In vivo antitumor effects of unconjugated CD30 monoclonal antibodies on human anaplastic large-cell lymphoma xenografts.

CD30 is a M(r) 120,000 surface antigen identified originally by the Ki-1 monoclonal antibody (moAb) against primary and cultured Reed-Sternberg cells present in Hodgkin's disease and anaplastic large-cell lymphomas (ALCLs). Examination of two ALCL cell lines (Karpas 299 and Michel) demonstrated cell surface expression of CD30. Incubation of these lymphomas with two anti-CD30 moAbs that recognize the ligand-binding site (M44 or HeFi-1) resulted in significant growth inhibition in vitro, with significant decreases in cell viability. Another anti-CD30 moAb, Ber-H2, which recognizes a determinant not involved in ligand binding, had no effect on ALCL growth in vitro. When these human ALCL lines were transferred i.v. into mice with severe combined immune deficiency, the mice developed extensive metastasis in the s.c., brain, or eye tissues. The treatment of mice with either M44 or HeFi-1 anti-CD30 moAbs resulted in significant increases in survival, with some mice remaining disease free for more than 100 days. Thus, anti-CD30 treatment is efficacious for CD30+ ALCL cell lines in vivo, and unconjugated anti-CD30 moAbs may be of potential clinical use.

Role of daunorubicin in the induction therapy for adult acute myeloid leukemia.

PURPOSE: To evaluate the relationship of total-dose of daunorubicin (DNR) to the induction therapy and treatment outcome, we have administered individualized doses of DNR during induction treatment to patients with acute myelogenous leukemia (AML). PATIENTS AND METHODS: Ninety-two previously untreated adult patients with AML who entered our hospital were analyzed for the dose of DNR required to achieve complete remission (CR), the CR rate, disease-free survival (DFS), and overall survival (OS). Induction therapy consisted of DNR 40 mg/m2 daily intravenously from day 1 until the marrow was hypoplastic, cytarabine (Ara-C), prednisolone (PRD), and/or 6-thioguanine (6-TG). RESULTS: Eighty-three of 92 patients with adult AML were assessable for this study. Sixty-three (76%) patients achieved CR. Fifty-two of 63 CR patients achieved the CR in the first course of induction therapy, and 11 patients required the second course of induction therapy. The 5-year and 10-year DFS rates were 31.2% and 5-year and 10-year OS rates were 45.1% and 42.3%, respectively. The median total dose of DNR in the induction therapy was 280 mg/m2 (120 to 480 mg/m2). DNR dose did not influence the response to therapy and was not influenced by the initial WBC count or French-American-British (FAB) system classification. CONCLUSION: These results indicated that when the dose was linked to observed tumor response, the optimal dose of DNR in the induction therapy was approximately 280 mg/m2 (40 mg/m2 for 7 days), which is greater than the conventional dose of 40 to 60 mg/m2 for 3 days.

Myeloablative allogeneic hematopoietic stem cell transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia in adults: significant roles of total body irradiation and chronic graft-versus-host disease.

Disease-free survival in Philadelphia chromosome-positive ALL (Ph + ALL) is very poor, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is currently considered the only procedure with curative potential. To identify factors affecting transplant outcome, we analyzed the data from 197 Ph + ALL patients aged 16 years or older who had undergone allo-HSCT. The 5-year survival rates were 34% for patients in first complete remission (CR), 21% for those in second or subsequent CR, and 9% for those with active disease (P < 0.0001). Multivariate analysis showed four pre-transplant factors as significantly associated with better survival: younger age, CR at the time of transplantation, conditioning with total body irradiation, and HLA-identical sibling donor (P < 0.0001, P < 0.0001, P = 0.0301, P = 0.0412, respectively). Severe acute GVHD increased the risk of treatment-related mortality (TRM) without diminishing the risk of relapse, whereas chronic GVHD reduced the risk of relapse without increasing the risk of TRM. Thus, patients who developed extensive chronic GVHD had better survivals (P = 0.0217), and those who developed grade III-IV acute GVHD had worse survivals (P = 0.0023) than did the others.

Shortening of telomeres in recipients of both autologous and allogeneic hematopoietic stem cell transplantation.

Telomere length of peripheral blood mononuclear cells (PBMCs) from 23 autologous HSCT patients ranging from 4 to 61 years old, and 46 allogeneic HSCT recipients from 6 to 52 years old were studied to confirm whether excessive shortening of telomeres is associated with HSCT. After autologous HSCT, telomere length of PBMCs ranged from 6.8 to 12.0 kb. The comparison between transplanted PBMCs and PBMCs after autologous HSCT showed shortening by up to 1.9 kb (mean +/- s.d.: 0.64 +/- 0.50 kb). There was a difference between autologous HSCT patients and normal volunteers in the slopes of regression lines. After allogeneic HSCT, telomere length of PBMCs ranged from 6.8 to 12.0 kb. Telomeres of recipients were up to 2.1 kb (0.60 +/- 0.468 kb) shorter than those of donors. The slope of regression lines for allogeneic HSCT patients and normal volunteers were parallel. Although all patients were transplanted with more than 2.0 x 10(8) cells/kg, telomere length did not correlate with the number of transplanted cells. There was no significant correlation between telomere length and recovery of hematological parameters. However, three patients with an average telomere length of 6.8 kb after HSCT took a longer period to reach the normal hematological state. Taken together, these data suggest that most HSCTs are performed within the biological safety range of telomeres, while the patients who have telomeres shorter than 7.0 kb after HSCT should be observed carefully for long-term hematopoiesis and the occurrence of hematopoietic disorders.

Clinical impact of graft-versus-host disease against leukemias not in remission at the time of allogeneic hematopoietic stem cell transplantation from related donors. The Japan Society for Hematopoietic Cell Transplantation Working Party.

Acute graft-versus-host disease (GVHD) increases post-transplant mortality and morbidity, but exerts a potent graft-versus-leukemia (GVL) effect. To clarify the impact of GVHD on outcome after transplant in aggressive diseases, patients with acute myeloid or lymphoblastic leukemia (AML, n = 366 or ALL, n = 255) in nonremission states, or chronic myelogenous leukemia (CML, n = 180) in accelerated phase (AP) or blastic crisis (BC), who received allogeneic hematopoietic stem cell transplantation (HSCT) from a related donor between 1991 and 2000, were analyzed. Significant improvement in overall and disease-free survival (DFS) was detected with grade I acute GVHD in AML (P = 0.0002 for overall survival and 0.0009 for DFS, respectively) and in CML (P = 0.0256 and 0.0366, respectively), while the trend towards improved survival was observed in ALL. Relapse rate was lower in grade I acute GVHD than in grade II in all three diseases, suggesting that treatment for grade II GVHD may compromise the GVL effect associated with GVHD. Chronic GVHD was found to suppress relapse in CML and ALL, but not in AML, although no improvement in survival was observed in any disease category. Our results suggest that treatment for grade II acute GVHD may need to be attenuated in transplant for refractory leukemias.

Severe aplastic anemia associated with chronic natural killer cell lymphocytosis.

Chronic natural killer (NK) lymphocytosis involves a persistent increase in CD56+ large granular lymphocytes (LGLs) that is sometimes associated with immune-mediated complications, such as anemia and neutropenia. However, aplastic anemia (AA) is a rare complication. Here we describe 2 patients with severe AA who presented with persistent increases in NK cells. Their LGLs were positive for CD56, CD16, and intracellular interferon (IFN)-gamma but negative for CD3, Fas-ligand, and T-cell receptor rearrangement, findings that are compatible with NK cells. Not only the number of NK cells, but NK activity as well, was increased in both patients. The number of NK cells changed according to hematologic recovery and relapse in 1 case. Thus, there seemed to be a close relationship between NK cells and the progression of AA, at least in this instance. Further investigation of the clinical course of similar cases and the characteristics of NK cells is necessary.

Effects of CD40 stimulation in the prevention of human EBV-lymphomagenesis.

CD40 is a molecule present on B lineage cells, both normal and neoplastic. Signalling through CD40 has been demonstrated to promote B cell growth and differentiation in vitro. In contrast to its effects on normal B cells, we have found that CD40 stimulation can inhibit the growth of various aggressive histology human B cell lymphomas both in vitro and in vivo. Moreover, using a human/mouse chimera model in which human EBV-induced B cell lymphomas can spontaneously arise, we have found that CD40 stimulation an prevent the occurrence of this human lymphoma in mice. However, normal human B cell engraftment and function was not adversely affected in these mice by CD40 stimulation. This indicates that CD40 stimulation is selective in its effects on aggressive histology B cell lymphomas. Thus, CD40 stimulation either by antibody or a recombinant soluble ligand, may be of potential clinical use, not only in the treatment of EBV-induced B cell lymphomas, but also in their prevention.

[Myocardial hemorrhage due to high-dose cyclophosphamide treatment in a case of non-Hodgkin's lymphoma].

43-year-old male with non-Hodgkin's lymphoma which was resistant to standard treatment received high-dose chemotherapy followed by autologous stem cell transplantation. He had a past history of nephrectomy due to renal cell carcinoma. He had received adriamycin at a total dose of 280mg/m2, but had no episode of heart disease. His chest radiograph, electrocardiogram and serum creatinine were within normal ranges at the start of high-dose chemotherapy. He was given 120 mg/kg of cyclophosphamide (CPM) over two days. Serum creatinine levels elevated two days before transplantation, and he felt discomfort of the chest followed by severe arrhythmia. He died of heart failure one day after the transplantation. Postmortem examination revealed diffuse myocardial hemorrhage with degeneration and necrosis of the heart muscle. CPM is one of the useful antitumor alkylating agents for the treatment of malignant neoplasms. Although conventional doses of CPM can be used without adverse cardiac effects, high-dose CPM has been reported to induce cardiotoxicity in a few cases. Patients often develop fatal acute heart failure. For the safe use of high-dose CPM, we must consider about the dosing schedule, early detection of adverse cardiac effects, and patient risk factors.

[Artificial insemination using the husband's frozen sperm in a patient with chronic myelogenous leukemia after bone marrow transplantation].

A 37-year-old man with chronic myelogenous leukemia (CML) was scheduled to receive a bone marrow allograft from an HLA-matching sibling. He was married without children, and desired to have a child in the future. Sperm was collected before transplantation and frozen for preservation. Induction therapy performed using 8 mg/kg of busulfan, 120 mg/kg of cyclophosphamide, splenic irradiation (4.5Gy), and total body irradiation (10Gy), and then allogenic bone marrow transplantation (BMT) was carried out. His post-transplantation course was uneventful and cyclosporin therapy was finished on day 187. The Philadelphia chromosome disappeared on day 20 after BMT and PCR analysis was negative for the bcr/abl rearrangement, suggesting the possibility of cure. Accordingly, artificial insemination was attempted using the frozen sperm. His wife became pregnant after the 4th attempt and a healthy baby was delivered. Transplantation recipients often become sterile because they receive ultra-high doses of chemotherapy and irradiation. However, it is still possible to have children if sperm or ova are preserved prior to transplantation. This is thought to improve the quality of life after BMT.

[EPOCH therapy for relapsed/refractory lymphoid malignancies].

Patients with refractory or relapsed non-Hodgkin's lymphoma (NHL), acute T-cell leukemia (ATL), ATL lymphoma and acute lymphocytic leukemia (ALL) received EPOCH therapy. All were previously treated with doxorubicin (DOX), vincristine (VCR) and other drugs. The EPOCH treatment schedule is consisted with DOX (10 mg/M2/day, 5 days c.i.v.), VCR (0.4 mg/M2/day, 4 days c.i.v.), etoposide (50 mg/M2/day, 4 days c.i.v.), cyclophosphamide (750 mg/M2/day, day 6 i.v.) and prednisolone (60 mg/M2/day, 5 days p.o.). Twenty-one patients (ALL:10, NHL:8, ATLL:2, ATL:1) were assessable for response and toxicity. Two patients with ALL and NHL, respectively, achieved a complete remission and 3 patients obtained partial remission (NHL:2, ATLL:1). The hematological toxicity (grade > 1) included neutoropenia, anemia and thrombocytopenia, which were observed in 83.3%, 76.7% and 76.7% respectively, of total 30 EPOCH courses. The major non-hematological toxicities were nausea/vomiting, constipation and infection, but most of the toxicity were tolerable with sufficient clinical supportive care. These results indicate that continuous infusion of DOX, VCR and ETP might be effective in patients who were treated with, and presumed to be resistant to the same drugs administrated by bolus infusion.

[Rapid onset of hemolytic anemia after allogeneic bone marrow transplantation from an unrelated ABO major mismatched donor].

A 46-year-old woman with chronic myelogenous leukemia received allogeneic bone marrow transplantation from an unrelated human leukocyte antigen (HLA) matched (but mixed lymphocyte culture (MLC) positive to graft-versus host disease (GvHD) donor. The blood type of the recipient was A type Rh (+) while the donor blood type was B type Rh (+). The patient received busulfan 8 mg/kg, cyclophosphamide 120 mg/kg, and total-body irradiation 10 Gy before bone marrow transplantation. Short-term administration of methotrexate and cyclosporin was given for prophylaxis of GvHD. The mononuclear cells harvested from the donor were concentrated by COBE Spectra before bone marrow transplantation. Although engraftment of transplanted bone marrow in the recipient was confirmed on day 11, the patient suffered from severe anemia on day 10. Since the direct Coombs' test to A type red blood cells was positive, and anti-A antibody titer increased 16-fold, we diagnosed her anemia as hemolytic anemia caused by ABO mismatched transplantation. In addition to hemolytic anemia, she had skin symptoms of acute GvHD grade II, microangiopathic hemolytic anemia, and died of multiple organ failure on day 44. This experience indicated that some allogeneic transplant recipients are at risk of severe hemolytic anemia in the early stage after unrelated ABO mismatched donor and that it is necessary to establish proper treatment and prophylaxis.

[Prognostic significance of CD7 expression in adult acute myeloid leukemia].

To evaluate the prognostic significance of CD7 expression in de novo acute myeloid leukemia (AML), we studied 63 patients with AML who had been admitted to our hospital between September 1989 and January 1996. Even of the patients were later eliminated from the study (9 due to insufficient surface marker analyses, and 2 due to early death). The remaining 52 patients (median age: 42.5 years) were evaluated for morphologic subtype, immunophenotypic classification, complete remission (CR), disease-free survival (DFS) and overall survival (OS). All 52 patients were grouped by the French-American-British classification system: 10 as M1, 16 as M2, 11 as M3, 8 as M4, 5 as M5, and 2 as M6. Ten of the patients expressed CD7 on their leukemia cells (positive rate > or = 25) and were classified as CD7(+)AML, with morphological subtypes as follows: 3 as M1, 6 as M2, and 1 as M3. Thirty-three of the 42 patients with CD7 + AML (78.6%) and 6 of the 10 patients with CD7 + AML (40%) achieved CR. DFS and OS rates for the patients with CD7(+)AML were 22.1% and 35.4%, respectively; those for the CD7(+)AML patients were 53.3% and 44.4%, respectively. No significant differences in gender hematological findings, clinical manifestations such as hepatosplenomegaly, lymphadenopathy, or incidence of central nervous system involvement, CR rate, and DFS distinguished patients with CD7(+)AML from those with CD7(+)AML. These suggest that CD7 expression is unlikely to be a prognostic factor in AML.

[Component transfusion in cancer chemotherapy--platelet transfusion and granulocyte transfusion].

The role of component transfusion has become important in cancer chemotherapy. Recently, it has become possible to obtain large amounts of platelets and granulocytes by the mechanical development of continuous flow centrifugation or filtration leukopheresis. These methods have enhanced the clinical efficiency of platelet transfusion. Although, several reports of randomized controlled studies of granulocyte transfusion have been published, its effectiveness has not yet been clearly established.

[The role of daunorubicin in induction therapy for adult acute myeloid leukemia].

The relationship between the total dose of daunorubicin (DNR) in induction therapy and the treatment outcome were evaluated based upon individualized doses of DNR during induction therapy for patients with acute myeloid leukemia(AML). Ninety-two previously untreated adult AML patients admitted to our hospital were analyzed for the dose of DNR required for complete remission (CR), the CR rate, disease-free survival (DFS) and overall survival (OS). The induction therapy consisted of DNR (40 mg/m2/d, i.v., from D 1 until the marrow was hypoplastic), Ara-C, prednisolone, and/or 6-thioguanine. Eighty-three out of 92 patients were assessable. Sixty-three patients entered CR (76%), of whom 52 attained CR with the first course of induction therapy. The 10-year DFS and OS rates were 31.2% and 42.3%, respectively. The median total dose of DNR in the induction therapy was 280 mg/m2 (120-480 mg/m2), which was not influenced by initial WBC count, or FAB type. These results indicate that when the dose is linked to the observed tumor response, the optimal dose of DNR in the induction therapy is around 280 mg/m2 (40 mg/m2 x 7 times), which is higher than the conventional dose of 40-60 mg/m2 for 3 days. The higher dose of DNR in the induction therapy for adult AML should be selected when the feasibility of a new drug is evaluated in a randomized trial.

Persistent nucleated red blood cells in peripheral blood is a poor prognostic factor in patients undergoing stem cell transplantation.

We compared detection rates and counts of nucleated red blood cell (NRBC) in the peripheral blood of survivors and nonsurvivors (total 44 patients) of stem cell transplantation. The rate of NRBC detection increased to 79.5% after transplantation. After engraftment, the detection rate of NRBC decreased to 17.0% in survivors, but increased to 100% in nonsurvivors. The NRBC count increased after transplantation in both groups. This increase was transient in survivors, but increased after engraftment in nonsurvivors. The mean NRBC count after engraftment was 872 vs. 40.3 for nonsurvivors vs. survivors, respectively. At postengraftment, all patients who were negative for NRBC survived, but 10 of the 15 patients who were positive for NRBC died (66.7%). The survival rates of patients with a NRBC count >200 x 10(6)/l were significantly lower than those of patients whose counts were <100 x 10(6)/l. These data indicated that persistent NRBC in peripheral blood is a poor prognostic factor, and suggested that monitoring NRBC after SCT might provide useful clinical information.

[The combination method for diagnosis of meniscus lesion in the knee (author's transl)].

Diagnostic criteria were established to improve the diagnostic accuracy of the meniscus lesion of the knee. Diagnostic criteria consist of combination of clinical scores and examination findings. Twelve findings probably occurring in meniscus lesion were selected and clinical scores were empirically assigned. Namely, they were such as the followings. 1. Locking phenomenon (30 points) 2. Snapping in movements (20 points) 3. Mass palpable on joint line in movement (20 points) 4. Locking-like phenomenon (15 points) 5. Giving-way (10 points) 6. Screw-home movement disturbance (10 points) 7. Quadriceps atrophy (10 points) 8. Clinical nomenclature test (10 points 9. Tenderness on joint line (5 points) 10. Full flexion disturbance (5 points) 11. Patella floating (3 points) 12. Pain in stepping upward and downward (1 point) Examination findings were classified into four groups according to their appearance as follows. 1. Typical...... Arthrogram shows abnormal line or pooling of contract medium and reveals the type of lesion in meniscus. Arthroscopy reveals lesion in meniscus directly. 2. Definitive...... Arthrogram shows abnormal line or pooling of contract medium, but does not reveal the type of lesion. Arthroscopy doesn't reveal lesion on meniscus directly but demonstrates abnormality occurring in meniscus lesion. 3. Suspective...... Arthrogram shows dullness of triangular corner or interruption of meniscus line, or deformity of meniscus image. Arthroscopy reveals discoloration or abnormal mobility of meniscus. 4. Nothing particular...... Arthrogram shows intact meniscus. Arthroscopy reveals intact meniscus. Diagnostic criteria, 1. When clinical score is more than 40 points, more than "suspective" results of clinical examination are required. 2. When clinical score is between 39 and 30 points, more than "definitive" results of clinical examination are required. 3. When clinical score is under 30 points, "typical" results of clinical examination are necessary. According to these criteria, 100 meniscectomies have been performed over 5 consecutive years. Since false positive results were obtained in none, the diagnostic value of the present criteria was 100%. This figure compares favorably with any values previously reported.

Induction of alloantigen-specific T cell tolerance through the treatment of human T lymphocytes with wortmannin.

Signaling through the CD28 molecule on T cells by its natural ligand, B7, on APCs has recently been shown to require the presence of an active phosphatidylinositol 3-kinase pathway to mediate some of its costimulatory activities (1-7). Using the phosphatidylinositol 3-kinase inhibitor, wortmannin (WN) (8), on human and murine T cells, we have inhibited B7-1-mediated T cell activation and induced Ag-specific tolerance. The addition of WN and/or the B7-1 antagonist, CTLA4Ig, to primary human T cell cultures stimulated with B7-1-transfected allogeneic melanoma cell lines inhibited the generation of alloantigen-specific proliferative and cytolytic responses in vitro. Subsequent examination of these WN- and CTLA4Ig-treated primary T cell cultures revealed that these lymphocyte populations were tolerized to rechallenge with the priming alloantigens in secondary cultures in the absence of additional inhibitor(s). However, reactivity to a third party allogeneic stimulator remained intact. This WN-induced tolerance was reversed by the addition of high dose IL-2, but not IL-4 or IL-7, to the primary cultures, indicating that T cell anergy, not deletion, was responsible for this phenomenon. In vivo studies using a murine graft-vs-host disease (GVHD) model demonstrated that WN treatment of allogeneic donor lymphocytes in vitro failed to generate a significant GVHD in irradiated mouse recipients compared with control allogeneic donor lymphocytes. These findings suggest potentially novel therapeutic strategies for the prevention of GVHD.