[Autoimmune reactions to immune checkpoint inhibitors]. / Autoimmunologische Reaktionen bei Immun-Checkpoint-Inhibitoren.

Immune checkpoint inhibitors (ICI) have dramatically changed the face of cancer treatment and are gaining in importance. The ICIs have now been approved for the treatment of advanced cancers, including melanoma, non-small-cell and small cell lung cancers, renal cell carcinoma, Hodgkin's lymphoma, head and neck cancers and urothelial carcinoma and further indications are to be expected. The organs most affected by an autoimmune reaction are the intestines, the musculoskeletal system, skin, endocrine organs, the liver and the lungs. As the indications for immune checkpoint blockade expand and ICIs are used in combination, it becomes increasingly more important for rheumatologists to recognize immune-related adverse events (irAEs), their connection to cancer immunotherapy and how to treat these events appropriately. The role of rheumatologists will take on growing importance as immunotherapies become more common as standard treatment of cancer and when used earlier in the course of the disease. Previously controlled autoimmune diseases can deteriorate when using ICIs, so this is a consideration when evaluating patients. Increased awareness of inflammatory arthritis, as well as other rheumatic manifestations as an adverse association with cancer immunotherapies, is imperative for making the diagnosis. Treatment algorithms are based on the severity of symptoms but in the case of rheumatic disease, treatment often needs to be tailored to the individual. The general strategy for evaluation and management of irAEs includes a thorough evaluation for infections. Mild irAE may be self-limiting, while more severe reactions are generally steroid responsive, albeit with potentially high dosage requirements.

Favorable outcome in children and adolescents with a high proportion of advanced phase disease using single/multiple autologous or matched/mismatched allogeneic stem cell transplantations.

We determined the indication, outcome, and risk factors of single and multiple hematopoietic stem cell transplantation(s) (HSCT) in children and adolescents mostly with advanced disease. Forty-one out of 483 patients (8.5 %; median age 9 years) diagnosed at the University of Leipzig with hematological and oncological diseases required HSCT from 1999 to 2011. Patients had overall survival (OS) of 63 ± 10 and 63 ± 16 %, event-free survival (EFS) of 57 ± 10 and 42 ± 16 %, relapse incidence (RI) of 39 ± 10 and 44 ± 18 % and nonrelapse mortality (NRM) of 4 ± 4 and 13 ± 9 % at 10 years after one or more allogeneic and autologous HSCT, respectively. One patient in CR1 and five with advanced disease received two HSCT. Four of the six patients maintained/achieved CR for a median of 13 months. Three died of progression and one of NRM. Two patients had a third HSCT and one survived in CR +231 days after HSCT. Risk factors for OS and EFS were disease stage at HSCT and EBMT risk score. Center (pediatric or JACIE accredited pediatric/adult) was not a determinant for survival. Pediatric single and multiple HSCT are important curative approaches for high-risk malignant diseases with low NRM. Efforts to reduce high RI remain the major aim.

Comparable outcome after single-antigen-mismatched versus matched unrelated donor haematopoietic cell transplantation.

PURPOSE: Allogeneic haematopoietic stem cell transplantation (HSCT) is a proven treatment for patients with haematological malignancies. In this retrospective analysis, the impact of donor matching on outcome of unrelated HSCT was analysed in patients transplanted at the University of Leipzig. METHODS: From 2000 to 2009, 206 patients were transplanted from unrelated donors, of which 51 were mismatched (39 in 1 and 12 in ≥ 2 HLA-antigens), using peripheral blood or bone marrow grafts after total body irradiation and cyclophosphamide or busulfan and cyclophosphamide preparative regimens in combination with ATG. For graft-versus-host disease (GvHD) prophylaxis cyclosporine and MTX were administered. RESULTS: After a median follow-up of 49 months, outcome at 5 years in recipients of HLA-identical grafts was comparable to that of patients transplanted from HLA-incompatible donors with an overall survival (OS) of 52 % (95 % CI 43-61) versus 48 % (95 % CI 34-63), respectively (p = 0.48). Results were also comparable for event-free survival at 5 years [47 % (95 % CI 38-56) vs. 39 % (95 % CI 25-54); p = 0.44], relapse incidence (RI) [29 % (95 % CI 20-38) vs. 41 (95 % CI 25-57); p = 0.22] and non-relapse mortality [24 % (95 % CI 16-33) vs. 20 % (95 % CI 8-33); p = 0.84] in the matched versus mismatched groups. Incidence of acute and chronic GvHD was similar in both groups. Advanced disease (p = 0.02) and low-resolution typing (p = 0.04) are risk factors for OS and RI in univariate and multivariate analysis. CONCLUSIONS: Donors with one antigen mismatch are an acceptable option for patients with malignant disease for whom no fully matched donor is available.

Mito-FLAG with Ara-C as bolus versus continuous infusion in recurrent or refractory AML--long-term results of a prospective randomized intergroup study of the East German Study Group Hematology/Oncology (OSHO) and the Study Alliance Leukemia (SAL).

BACKGROUND: For patients with primary refractory or relapsed acute myeloid leukemia (AML), no treatment of choice has until now been defined to date. Cytarabine (Ara-C) is a key drug in the treatment of AML patients, there is still uncertainly regarding its optimal dose and infusion schedule. The aim of this study is to examine the impact of the Ara-C infusion schedule used as part of an intensive salvage regimen, in patients with relapsed or refractory AML. PATIENTS AND METHODS: A total of 252 adult patients (median age 59 years) with relapsed or refractory AML were randomly allocated to receive either Mito-FLAG with Ara-C as bolus (B) (1000 mg/m(2) over 1 h, every 12 h, days 1-5), or continuous infusion (CI) (150 mg/m(2) over 24 h, days 1-5) in combination with mitoxantrone, fludarabine, and granulocyte colony-stimulating factor (G-CSF). Autologous or allogeneic hematopoietic stem-cell transplantation was offered as consolidation therapy. Primary end point was the rate of complete remissions (CRs) after the first cycle of Mito-FLAG. RESULTS: The CR rates after Mito-FLAG (B) and Mito-FLAG (CI) were 54% and 43%, respectively (P = 0.1). There was no statistical difference between rates of grade 3/4 neutropenia, thrombocytopenia, mucositis, renal, and liver toxicity. More infections occurred, however, after Mito-FLAG (B) compared with Mito-FLAG (CI) (80% versus 69%, P = 0.01). The early death rate by day 42 was 13% in both arms. Median disease-free survival was comparable in the two arms (7.8 versus 7.1 months, P = 0.53) as was overall survival (7.1 versus 6.6 months, P = 0.53). CONCLUSION: A 5-day course of Ara-C 2 × 1000 mg/m(2) administered as bolus versus Ara-C 150 mg/m(2) administered by CI (in combination with mitoxantrone, fludarabine, and G-CSF), resulted in a nonsignificant trend in response rates in favor of Mito-FLAG (B) at the selected dose levels, but no differences in the survival outcome in relapsed or refractory AML. CLINICAL TRIAL NUMBER: LN_NN_2004_39/EudraCT number 2014-000083-18.

Early related or unrelated haematopoietic cell transplantation results in higher overall survival and leukaemia-free survival compared with conventional chemotherapy in high-risk acute myeloid leukaemia patients in first complete remission.

Between 1996 and 2004, a total of 708 patients were enrolled in the acute myeloid leukaemia (AML) '96 and '02 studies of the East German Study Group (OSHO). Of these, 138 patients (19.5%) had unfavourable cytogenetics defined as complex karyotype, del (5q)/-5, del (7q)/-7, abn (3q26) and abn (11q23). In all, 77 (56%) achieved complete remission 1 (CR1) after induction chemotherapy and were eligible for haematopoietic cell transplantation (HCT). HCT was performed after a median of two cycles of consolidation chemotherapy (CT) in the AML '96 and one cycle in the AML '02 study (P=0.03). After a median follow-up of 19 months, overall survival (OS) at two years was significantly better in the donor group (52+/-9%) versus the no-donor group (24+/-8%; P=0.005). Differences in outcomes were mainly because of a lower relapse incidence in patients after HCT (39+/-11%) compared with a higher relapse incidence in patients undergoing CT (77+/-10%; P=0.0005). Treatment-related mortality was low and not statistically significantly different between the two treatment groups (15+/-7 and 5+/-5% for HCT and chemotherapy, respectively; P=0.49).We conclude that early HCT from related or unrelated donors led to significantly better OS and leukaemia-free survival compared with chemotherapy in patients with unfavourable karyotype.

Treatment of invasive pulmonary aspergillosis in neutropenic patients by additional bronchoscopic amphotericin B instillation.

BACKGROUND: Invasive pulmonary aspergillosis (IPA) remains a life-threatening condition despite systemic antifungal therapy. OBJECTIVES: This retrospective analysis investigated whether additional bronchoscopic instillation of amphotericin B (amB) would improve efficacy of antifungal treatment in patients with haematological malignancies suffering from IPA. METHODS: Twenty patients (40.6 +/- 14.2 years, 14 male) with preceding chemotherapy, bone marrow or stem cell transplantation complicated by severe IPA who did not respond sufficiently to systemic antifungal therapy were additionally treated by repeated bronchoscopic instillations of amB solution (91 instillations, on average 4.6 +/- 2.2 instillations per patient over a period of 24.1 +/- 21.0 days). Therapeutic response to this combined treatment regimen was monitored by chest X-ray and CT scan. RESULTS: The mean infiltration sizes during systemic antifungal therapy alone (mean duration 11.9 +/- 9.9 days) did not change significantly. However, after additional bronchoscopic instillation of amB solution infiltration sizes were reduced significantly (p < 0.05). A total resolution of infiltrates was seen in 3 and a partial reduction in 13 of 20 patients. Mean duration of total antifungal treatment was 50.1 +/- 24.0 days. The mean follow-up period was 34.1 +/- 31.2 months. The IPA-related mortality rate was 18.8% (3 of 16 patients). CONCLUSIONS: Additional bronchoscopic instillation of amB may improve the efficacy of systemic antifungal therapy in patients with haematological malignancies complicated by severe IPA. Bronchoscopic instillation of amB should be considered as an additional treatment option in cases with IPA unresponsive to systemic therapy.

[Late effects after chemotherapy]. / Folgeerkrankungen nach Chemotherapie.

Today, about 60% of adult patients and 80% children diagnosed with cancer will survive 5 years after diagnosis. Approximately two thirds of cancer survivors will experience at least one late effect, and about one third severe or life threatening late effects. The aim of cancer treatment today is to cure the malignant disease but at the same time, to minimize the incidence of post-treatment complications. In the current overview we summarize, based on the most recent publications, typical late effects in cancer survivors.

Treatment of bendamustine and prednisone in patients with newly diagnosed multiple myeloma results in superior complete response rate, prolonged time to treatment failure and improved quality of life compared to treatment with melphalan and prednisone--a randomized phase III study of the East German Study Group of Hematology and Oncology (OSHO).

PURPOSE: This randomized phase III study compared bendamustine and prednisone (BP) to standard melphalan and prednisone (MP) treatment in previously untreated patients with multiple Myeloma (MM). PATIENTS AND METHODS: To be included, patients had to have histologically and cytologically proven stage II with progressive diseases or stage III MM. They were randomly assigned to receive BP (n=68) or MP (n=63). The primary endpoint was the time to treatment failure (TTF). Secondary endpoints included survival, remission rate, toxicity and quality of life. RESULTS: The overall response rate was 75% in the BP and 70% in the MP group. A significantly higher number of patients treated with BP achieved a complete remission than did patients receiving MP (32 vs. 13%; P=0.007), and the maximum response was achieved more rapidly in patients treated with BP compared to those receiving MP (6.8 vs. 8.7 cycles; P<0.02). TTF and remission duration were significantly longer in the BP group. Patients receiving BP had higher QoL scores and reported pain less frequently than patients receiving MP. CONCLUSION: BP is superior to MP with respect to complete remission rate, TTF, cycles needed to achieve maximum remission and quality of life and should be considered the new standard in first-line treatment of MM patients not eligible for transplantation.

Transmission of donor illness by stem cell transplantation: should screening be different in older donors?

With increasing donor age, the potential of transmitting diseases from donor to recipient reaches new dimensions. Potentially transmittable diseases from donors include infections, congenital disorders, and acquired illnesses like autoimmune diseases or malignancies of hematological or nonhematological origin. While established nonmalignant or malignant diseases might be easy to discover, early-stage hematological diseases like CML, light-chain multiple myelomas, aleukemic leukemias, occult myelodysplastic syndromes and other malignant and nonmalignant diseases might not be detectable by routine screening but only by invasive, new and/or expensive diagnostic tests. In the following article, we propose recommendations for donor work-up, taking into consideration the age of the donors. In contrast to blood transfusions, stem cells from donors with abnormal findings might still be acceptable for HCT, when no other options are available and life expectancy is limited. This issue is discussed in detail in relation to the available donor and stem cell source. Finally, the recommendations presented here aim at harmonized worldwide work-up for donors to insure high standard quality.

Hematopoietic cell transplantation from related and unrelated donors after minimal conditioning as a curative treatment modality for severe paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal disorder caused by a somatic mutation of the X-linked phosphatidylinositol glycan class A gene. Allogeneic hematopoietic cell transplantation (HCT) after high-dose conditioning is the only curative treatment; however, it is associated with high treatment-related mortality. Here, we report on allogeneic HCT for PNH after minimal conditioning. Seven adult patients with high-risk PNH underwent peripheral blood HCT from HLA-A-, -B-, -C-, -DRB1-, and -DQB1-matched related (n = 2) and unrelated (n = 5) donors. Conditioning included fludarabine 30 mg/m(2)/d on days -4 to -2 and 2 Gy of total body irradiation on day 0. After HCT, patients were given immunosuppressive therapy with oral cyclosporine starting on day -3 and mycophenolate mofetil starting on day 0. All 7 patients attained durable engraftment. After 28 days, a median of 77% (range, 53%-96%) T-cell donor chimerism was found in bone marrow and peripheral blood. T-cell chimerism increased to 91% (range, 76%-100%) on day +180 and to 100% in all surviving patients after 12 months. All 7 patients attained complete remissions of their disease. Four patients are alive 13 to 38 months after HCT. Three patients died of treatment-related mortality, 1 because of complications after acute pancreatitis and multiorgan failure, 1 because of infection related to chronic graft-versus-host disease (GVHD), and 1 because of bleeding after liver biopsy for late subacute/chronic GVHD. Allogeneic HCT from related and unrelated donors after minimal conditioning is a new and potentially curative option for patients with advanced PNH.

Filgrastim mobilization and collection of allogeneic blood progenitor cells from adult family donors: first interim report of a prospective German multicenter study.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) mobilized peripheral blood progenitor cells (PBPCs) from healthy individuals are a rapidly emerging alternative source to bone marrow for allogeneic transplantation. Although widely applied in the meantime, only limited information on feasibility and safety of mobilization and collection of PBPCs is currently available from prospective multicenter studies specifically designed to investigate this donation modality. This ongoing multicenter study on the performance as well as the short- and long-term safety profile of rhG-CSF-induced mobilization and collection of PBPCs was initiated in October 1999. The study is designed to recruit a total of 300 healthy family donors who will be followed regularly for a period of 5 years after donation. The first interim report presented here summarizes results obtained after enrollment of 150 donors from nine German institutions. The study protocol allowed the individual choice between two dose regimens of rh-CSF (10 micro g/kg per day vs 2x8 micro g/kg per day of donor body weight). The primary endpoint was defined as a yield of > or =5x10(6) CD34(+) cells/kg of recipient body weight in a single leukapheresis product. This endpoint was attained by 50% of donors receiving the lower rhG-CSF dose regimen and by 75% of donors with the higher dose regimen ( p<0.0009). A total of 478 acute adverse events attributable to the mobilization procedure were recorded and manifested predominantly as transient bone pain and headaches (80%). No persistent hematologic or nonhematologic adverse events have occurred in this study so far. Thus, the current experience in a prospective multicenter study supports previous single-center and retrospective registry reports in that the collection of PBPCs after rhG-CSF mobilization is feasible and associated with frequent, but generally mild and acceptable side effects.

Chemotherapy for mobilisation of Ph-negative progenitor cells from patients with CML: impact of different mobilisation regimens.

Mobilised peripheral blood stem cells are widely used for autografting in patients with chronic myeloid leukaemia (CML) and it is generally thought that a high proportion of Ph-negative progenitor cells in the graft is desirable. We report here the results of 91 stem cell mobilisations performed with various chemotherapy regimens followed by G-CSF. We show that mobilisation of Ph-negative cells is possible after diagnosis as well as in advanced stages of the disease. The yield of Ph-negative cells is highly dependent on the chemotherapy regimen: while the combination of idarubicin and cytarabin for 3-5 days (IC3-5) mobilised Ph-negative cells in most patients, high-dose cyclophosphamide was ineffective. Mobilisation of Ph-negative progenitor cells after IC3 was at least as effective as after IC5; however, less apheresis sessions were required, and toxicity was much reduced after IC3. Compared to historical controls, IC was equally effective as the widely used ICE/miniICE (idarubicin, cytarabin, etoposide) protocol. No correlation was found between graft quality and the cytogenetic response to subsequent treatment with interferon-alpha. We conclude that IC3 is an effective and well-tolerated regimen for mobilising Ph-negative cells that compares well with more aggressive approaches such as IC5 and ICE/miniICE.

Pericarditis after allogeneic peripheral blood stem cell transplantation caused by Legionella pneumophila (non-serogroup 1).

A case of Legionella pericarditis caused by a Legionella pneumophila isolate other than serogroup 1 is reported in a 59-year-old man after allogeneic peripheral blood stem cell transplantation. On admission a 5 mm pericardial effusion was detected on echocardiography. Antibodies were detected against L. pneumophila serogroups 7 to 14 using the antigen pool and against serogroup 12 alone. Antibodies were not detected against the serogroup 1 to 6 antigen pool. The patient's clinical condition improved dramatically after treatment with clarithromycin and an echocardiography revealed the total disappearance of the pericardial effusion.

Pulmonary nocardiosis with cutaneous involvement mimicking a metastasizing lung carcinoma in a patient with chronic myelogenous leukaemia.

We report a unique case of a man suffering from chronic myelogenous leukaemia who presented with clinical symptoms, X-ray, and bronchoscopical findings consistant with a bronchopulmonary space-occupying process which was suspected to be a central lung carcinoma as a secondary de novo malignancy. In addition, the patient developed several subcutaneous nodular livid red lesions on the left forearm which were considered to be cutaneous metastases of the presumptive lung malignancy. Treatment was started with percutaneous radiation of the mediastinum over a period of ten days with a total dose of 25 Gray. The patient died from circulatory and respiratory failure. Only post mortem pathological examination was indicative of a nocardiosis of the lungs with haematological spread to eosophagus, pleura, and subcutaneous skin of the left forearm. Unfortunately, diagnosis of nocardiosis could not finally proven by culture or molecular biological methods. A lung carcinoma or an infiltrate of residual or relapsing chronic myelogenous leukemia in the lung could be definitely ruled out.

[Pyoderma gangrenosum and portal vein thrombosis in a 33-year-old female patient]. / Pyoderma gangraenosum und Pfortaderthrombose bei einer 33jährigen Patientin.

HISTORY AND CLINICAL FINDINGS: The diagnosis of pyoderma gangraenosum (PG) was made in a 33-year-old woman with ulcerative (palm-sized) skin changes and pain of the lower leg that had developed over two weeks and was accompanied by fever (39 degrees C). Treatment with prednisolone and azathioprine was initiated. As soon as the medication was reduced new skin changes developed. Two months after onset of the illness she had to be hospitalized because of fever, epigastric pain on pressure and deteriorating general condition. Physical examination provided no significant further information. LABORATORY RESULTS: The differential count demonstrated leucocytosis (15.5 Gpt/l) with a marked monocytosis (25%) as well as anaemia (haemoglobin concentration 5.2 mmol/l). C-reactive protein was elevated (120.20 mg/l). Thromboplastin time was 60%, D-dimer 1000 micrograms/l, thrombin-antithrombin-III complex 9.7 micrograms/l. ADDITIONAL INVESTIGATIONS: Sonography and computed tomography of the upper abdomen revealed splenomegaly, ascites, thrombosis of the portal, splenic and superior mesenteric veins. Bone marrow puncture showed marked increase in blasts (14%) and monocytes (10%). TREATMENT AND COURSE: The findings indicated chronic myelomonocytic leukaemia with PG and the described venous thromboses. The cutaneous changes completely receded on administration of hydroxyurea (1.0 g/d). Other causes of the skin eruption were excluded. Phenprocoumon (INR between 2 and 3) was given in treatment of the thromboses. CONCLUSION: When PG is diagnosed, intensive search for an underlying cause must be undertaken, because of its frequent association with serious systemic disease. Only early specific treatment will improve the skin condition.

Second unrelated bone marrow transplantation without additional conditioning therapy after engraftment failure.

A 37-year-old female highly alloimmunized by multiple transfusions received a sex matched HLA-identical unrelated bone marrow transplant for hypoplastic MDS-RA with moderate myelofibrosis. Conditioning consisted of total body irradiation, cyclophosphamide and ATG, GVHD prophylaxis consisted of CsA, MTX and prednisolone. The CD34+ stem cell content of the first graft was relatively low due to an inadequate harvest. The patient appeared not to have engrafted by day 23 post-BMT. She therefore received a second sex mismatched HLA-identical unrelated bone marrow graft on day 25 after two days of 3.5 mg/kg methylprednisolone from a different donor. Over the ensuing days, the first marrow showed slow engraftment followed by engraftment of the second graft. The first graft was then rejected, as monitored by peripheral blood studies of chimerism. No signs of acute GVHD were observed. Despite successful trilineage engraftment and complete second donor chimerism, the patient died from disseminated toxoplasmosis encephalitis and pneumonia on day +104.

[Detection of mixed lymphoid chimerism after allogeneic bone marrow transplantation: demonstration by interphase cytogenetics in paraffin-embedded tissue]. / Gemischter lymphoider Chimärismus nach allogener Knochenmark-transplantation: Nachweis durch Interphase-Zytogenetik an paraffineingebettetem Gewebe.

In bone marrow transplantation (BMT) the detection of residual host lymphoid or haematopoietic cells surviving conditioning therapy is because of its association to graft-versus-host disease, graft-versus-leukemia reaction, and relapse of leukemia a matter of great interest. We studied the occurrence of this mixed lymphoid chimerism (MC) in the formol-fixed lymphatic tissue of lymph nodes and spleen from 21 autopsies after allogeneic sex-mismatched BMT (5 females, 16 males, survival 5 to 1140 days after BMT). In situ hybridisation with biotinylated centromer-specific anti-X- and anti-Y-chromosome probes was performed on pepsin-digested paraffin sections. The number of double X-, single X-, and Y-chromosome bearing cells was analysed microscopically. Because of artefacts only 14 cases remained for valid investigation. MC was detected in 6 cases (5 out of 11 males 5 days to 840 days and 1 out of 3 females 76 days after BMT). MC occurred after whole body irradiation with 10 Gy (n = 5) and 7 Gy (n = 1). In 1 autopsy relapse of leukemia caused host cell infiltration. Cases with MC did not express histological signs of acute or chronic graft-versus-host disease, but 5 out of 8 with complete lymphoid chimerism did. The sensitivity of interphase cytogenetics on paraffin embedded tissue is low.

[Immunohistologic investigations of paraffin-embedded lymph nodes after bone marrow transplantation in autopsy samples]. / Immunhistologische Untersuchungen an paraffineingebetteten Lymphknoten Verstorbener nach Knochenmarktransplantation.

A histological and immunohistochemical analysis of paraffin-embedded lymph nodes from 31 autopsies after bone marrow transplantation (BMT) was performed (20 allogeneic, 10 autologous, 1 syngeneic). Monoclonal antibodies against CD 45RB, CD 20, CD 21, CD 35. CD 43, CD 45RO, CD 76 and Ki-B3, and antisera for detection of S 100-protein and immunoglobulin isotypes were used. None of the lymph nodes showed a regular reconstitution. The lymphoid cells, scattered in a diffuse pattern, were mainly CD 43-positive. Most of them also expressed the CD 45RO antigen. CD 20- and Ki-B3 positive lymphoid cells were nearly absent within the first 100 days after BMT. After that time B cell follicles were detectable in a few cases. Surprisingly, in nearly all cases with infectious complications, numerous plasma cells could be found. The origin of this plasma cells is discussed.

T-cell depletion and haematological side effects of two cytotoxic monoclonal antibodies.

We investigated two cytotoxic monoclonal antibodies of BL-series (BL-IIIB4 and BL-IIG2) according to T-lymphocyte depletion from bone marrow. Both antibodies work together with human complement similar Campath-1, which was tested parallelly. The extent of T-cell depletion is about 95% for all three antibodies. On the other hand the haemopoietic side effects tested by CFU-GM recovery and LTBMC are for the BL-antibodies not as strong as for Campath-1, especially in view of LTBMC. T-cell regeneration could be shown in long term cultures. Our results indicate a possible suitability of the two investigated antibodies for T-cell depletion of bone marrow.