Comorbidity and treatment decision-making in elderly non-Hodgkin's lymphoma patients: a survey among haematologists

BACKGROUND

Elderly patients with non-Hodgkin's lymphoma (NHL) are often not treated with standard immunochemotherapy and this might have a negative impact on their survival. Little is known about the determinants that play a role in treatment decision-making of clinicians regarding elderly patients with NHL. The objective of this study was to gain more insight into these determinants.

METHODS

A survey was conducted amongst haematologists in the Netherlands. The survey contained questions about comorbidity, polypharmacy, social setting, nutritional status, depression, mild cognitive impairment, dementia, activities of daily living (ADL) and instrumental activities of daily living (IADL) in relation to treatment decisions in elderly NHL patients.

RESULTS

Of all comorbidities, respondents designated cognitive disorders and cardiovascular comorbidity as the most important factors when assessing whether an older patient with NHL is eligible for curative treatment. Also in decreasing degree of importance ADL, IADL and depressive disorder are frequently included in treatment decision-making. Almost half of the respondents feel that treatment of the elderly person is complicated as a result of a lack of scientific evidence.

CONCLUSION

Haematologists are aware of coexisting problems in elderly patients and they frequently take comorbidities, cognitive disorders and functional status into consideration in treatment decision-making. Future studies are needed to determine the exact role that these factors should play in the treatment of elderly patients. Furthermore, haematologists feel that treatment of the elderly is complicated and there is a lack of scientific evidence, and therefore older adults should be better represented in clinical trials.

A survey on diagnostic methods and treatment strategies used in patients with Waldenström's macroglobulinaemia in The Netherlands

BACKGROUND

Waldenström's macroglobulinaemia (WM) is defined as a lymphoplasmacytic lymphoma primarily located in the bone marrow, accompanied by an immunoglobulin M (IgM) monoclonal protein in the serum. The symptoms are highly variable, which can sometimes lead to a diagnostic delay. Currently, there is a wide range of therapeutic options used for the management of WM but no approved therapeutic agents are available specifically for this disease.

METHODS

An online survey was prepared and sent out to haematologists and haemato-oncologists in The Netherlands, together with an invitational letter to participate. Information was gathered about the preferred methods of diagnosing and treating patients with WM in general, and about the last WM patient diagnosed in their department.

RESULTS

83 (31.8%) responses were obtained, out of which 68 (81.9%) contained responses to all three parts of the survey. The respondents most commonly used either rituximab-CVP or chlorambucil as first-line treatment, whereas rituximab in combination with purine analogues was the most frequently applied second-line treatment. The prevention of an IgM 'flare' was managed by the respondents in various ways, and rituximab maintenance treatment was not commonly used.

CONCLUSION

This survey indicates that in general the diagnostic methods and treatment options for WM are well known to a representative number of Dutch haematologists. The areas of uncertainty are knowledge about asymptomatic vs symptomatic disease, risk of hyperviscosity in relation to IgM level, and the occurrence and prevention of an IgM 'flare'. These issues should be addressed in clinical research and guidelines to improve care for WM patients in The Netherlands.

Clinical experience with different dosing schedules of decitabine in patients with myelodysplastic syndromes (MDS)

7011

Background: Decitabine, a potent DNA hypomethylating agent, has demonstrated efficacy in MDS patients using two dosing regimens: 15 mg/m2 intravenous (IV) over 3 hours (hrs) every (q) 8 hrs for 3 days q 6 weeks (wks) and 20 mg/m2 IV over 1 hr once daily for 5 consecutive days q 4 wks. Methods: Results were reviewed from two randomized phase 3 studies comparing the 3-day dosing schedule of decitabine with supportive care, D-0007 and EORTC-06011, and two phase 2 studies with the 5-day dosing schedule, DACO-020 and ID03–0180. Data from each clinical trial supporting overall improvement, duration of improvement, time to AML or death, progression-free survival (PFS), and transfusion independence was assessed. Results: Patients had IPSS classification scores of intermediate-2 or high-risk (D-0007, 70%; EORTC-06011, 93%; ID03–0180, 66%; DACO-020, 46%) and de novo MDS (D-0007, 87%; EORTC-06011, 88%; ID03–0180, 70%; DACO-020, 89%). Comparable overall improvement (complete response [CR] + partial response [PR] + hematologic improvement [HI]), time to AML or death, and PFS was observed across all trials (Table). The duration of improvement ranged between 9.2 and 11.3 months. A trend was observed for improved outcomes with an increased number of decitabine treatment cycles. Conclusions: Overall improvement rates by IWG criteria exceeded 30% in all 4 studies. Higher overall improvement rates corresponded to increased median number of treatment cycles. Increasing the number of decitabine treatment cycles administered may provide additional benefit to MDS patients.

[Table: see text]

[Table: see text]

Epigenetic therapy with decitabine for myelodysplasia and leukemia

New therapeutic approaches are being developed for the treatment of cancer patients. Increasingly, drugs are being produced based on new insight into the intracellular processes in the cancer cell. Recently the typical epigenetic changes in the tumor cell have been considered as a therapeutic target. Several drugs have shown potential epigenetic activity. Decitabine (5-aza-2´-deoxycytidine, Dacogen™) is one of the drugs that is able to induce changes in the methylation status of DNA. In this article the authors present an overview of this drug with regard to the chemistry, pharmacokinetics and the data that support its role as the new therapeutic agent in leukemia and myelodysplastic syndrome.

Splenectomy for the treatment of thrombotic thrombocytopenic purpura

Plasma exchange is the treatment of choice for patients with thrombotic thrombocytopenic purpura (TTP) and results in remission in >80% of the cases. Treatment of patients who are refractory to plasma therapy or have relapsing disease is difficult. Splenectomy has been a therapeutic option in these conditions but its value remains controversial. We report on a series of 33 patients with TTP who were splenectomised because they were plasma refractory (n = 9) or for relapsed disease (n = 24). Splenectomy generated prompt and unmaintained remissions in all except five patients, in whom remission was delayed (n = 4) or who died with progressive disease (n = 1). Four postoperative complications occurred: one pulmonary embolism and three surgical complications. Median follow-up after splenectomy was 109 months (range 28-230 months). The overall postsplenectomy relapse rate was 0.09 relapses/patient-year and the 10-year relapse-free survival (RFS) was 70% (95% CI 50-83%). In the patients with relapsing TTP, relapse rate fell from 0.74 relapses/patient-year before splenectomy to 0.10 after splenectomy (P < 0.00001). Two patients died from first postsplenectomy relapse. Although these results are based on retrospective data and that the relapse rate may spontaneously decrease with time, we conclude that splenectomy, when performed during stable disease, has an acceptable safety profile and should be considered in cases of plasma refractoriness or relapsing TTP to reach durable remissions and to reduce or prevent future relapses.

The presence of an HLA-identical sibling donor has no impact on outcome of patients with high-risk MDS or secondary AML (sAML) treated with intensive chemotherapy followed by transplantation: results of a prospective study of the EORTC, EBMT, SAKK and GIMEMA Leukemia Groups (EORTC study 06921)

This report used the framework of a large European study to investigate the outcome of patients with and without an HLA-identical sibling donor on an intention-to-treat basis. After a common remission-induction and consolidation course, patients with an HLA-identical sibling donor were scheduled for allogeneic transplantation and patients lacking a donor for autologous transplantation. In all, 159 patients alive at 8 weeks from the start of treatment were included in the present analysis. In total, 52 patients had a donor, 65 patients did not have a donor and in 42 patients the availability of a donor was not assessed. Out of 52 patients, 36 (69%) with a donor underwent allogeneic transplantation (28 in CR1). Out of 65 patients, 33 (49%) received an autograft (27 in CR1). The actuarial survival rates at 4 years were 33.3% (s.e. = 6.7%) for patients with a donor and 39.0% (s.e. = 6.5%) for patients without a donor (P = 0.18). Event-free survival rates were 23.1% (s.e. = 6.2%) and 21.5% (s.e. = 5.3%), respectively (P = 0.66). Correction for alternative donor transplants did not substantially alter the survival of the group without a donor. Also, the survival in the various cytogenetic risk groups was not significantly different when comparing the donor vs the no-donor group. This analysis shows that patients with high-risk myelodysplastic syndrome and secondary acute myeloid leukemia may benefit from both allogeneic and autologous transplantation. We were unable to demonstrate a survival advantage for patients with a donor compared to patients without a donor.

Chemotherapy only compared to chemotherapy followed by transplantation in high risk myelodysplastic syndrome and secondary acute myeloid leukemia; two parallel studies adjusted for various prognostic factors

Comparisons of the effectiveness of chemotherapy and transplantation in AML in first complete remission (CR) have focused almost exclusively on patients with de novo disease. Here we used Cox modelling to compare these strategies in patients with MDS and s-AML treated by the Leukemia Group of the EORTC or at the MD Anderson Cancer Center. All patients were aged 15-60. The 184 EORTC patients received conventional dose ara-C + idarubicin + etoposide for remission induction, and after one consolidation course, were scheduled to receive an allograft, or an autograft if a sibling donor was unavailable. The 215 MDA patients received various high-dose ara-C containing induction regimens, and in CR, continued to receive these regimens at reduced dose for 6-12 months. CR rates were 54% EORTC and 63% MDA (P = 0.09). Sixty-five of the 100 EORTC patients who entered CR received a transplant in first CR. Disease-free survival in patients achieving CR was superior in the EORTC cohort, the 4-years DFS rates were 28.9% (s.e. = 4.8%) EORTC vs 17.3% (s.e. = 3.7%) MDA (P = 0.017). Survival from CR was not significantly different in the EORTC and MDA groups, as was survival from start of treatment. After accounting for prognostic factors the conclusions were unchanged. Despite various problems with the analysis discussed below, the data suggest that neither transplantation nor chemotherapy, as currently practised, can be unequivocally recommended for these patients in first CR and that questions as to the superior modality may be less important than the need to improve results with both.

Intensive chemotherapy followed by allogeneic or autologous stem cell transplantation for patients with myelodysplastic syndromes (MDSs) and acute myeloid leukemia following MDS

This study investigated the feasibility of allogeneic (alloSCT) and autologous stem cell transplantation (ASCT) as postconsolidation therapy for patients with myelodysplastic syndromes (MDSs) or acute myeloid leukemia after MDS. Patients with a histocompatible sibling were candidates for alloSCT and the remaining patients for ASCT. Remission-induction therapy consisted of 1 or 2 courses with idarubicin, cytarabine, and etoposide, followed by one intensive consolidation course with cytarabine and mitoxantrone. Initially, bone marrow cells were used for ASCT. Subsequently, mobilized blood stem cells were used in an attempt to shorten posttransplantation hypoplasia. With a median follow-up of 3.6 years the 184 evaluable patients showed a 4-year survival rate of 26% and a median survival of 13 months. The remission-induction chemotherapy induced complete remission (CR) in 100 patients (54%). The 4-year disease-free survival (DFS) rate was 29% and the median DFS was 12 months. Twenty-eight of 39 patients (72%) with a donor were allografted in CR-1, including 2 patients who underwent transplantation in CR-1 without a consolidation course. Thirty-six of 59 patients (61%) without a donor received ASCT in CR-1. The 4-year DFS rates in the group of patients with or without a donor were 31% and 27%, respectively. The 4-year survival rates from CR were 36% and 33%, respectively. This large prospective study shows the feasibility of both alloSCT and ASCT. This treatment approach leads to a relatively high remission rate, and the majority of patients in remission received the SCT in CR-1. The ongoing study investigates whether this approach is better than treatment with chemotherapy only.

Cytogenetic responses in high-risk myelodysplastic syndrome following low-dose treatment with the DNA methylation inhibitor 5-aza-2'-deoxycytidine

Decitabine (5-aza-2'-deoxycytidine) acts as a powerful demethylating agent in vitro. Clinically, low-dose decitabine ameliorates cytopenias including induction of trilineage responses in approximately 50% of patients with high-risk myelodysplastic syndrome (MDS). We examined the incidence and kinetics of cytogenetic responses to decitabine in these patients. Of 115 successfully karyotyped patients, 61 (53%) had clonal chromosomal abnormalities prior to treatment. Major cytogenetic responses were observed in 19 patients (31% of those with abnormal cytogenetics, 17% of all patients by intention-to-treat) after a median of three courses (range, 2-6) until best cytogenetic response. Progressive decrease of the abnormal clone over time was also determined using fluorescence in situ hybridization (FISH) analysis in two patients. Median duration of cytogenetic responses was 7.5 months (range, 3-15). Analysis of response by the International Prognostic Scoring System (IPSS) cytogenetic risk groups revealed three out of five cytogenetic responses (60%) in the IPSS 'low-risk' group, 6 out of 30 with 'intermediate risk' (20%) and 10 out of 26 in the 'high-risk' group (38%). Median survival in these cytogenetic subgroups was 30, 8 and 13 months respectively. The relative risk of death in patients achieving a major cytogenetic response was 0.38 (95% confidence interval 0.17-0.88) compared with patients in whom the cytogenetically abnormal clone persisted (P = 0.0213). In conclusion, repeated courses of low-dose decitabine induce cytogenetic remissions in a substantial number of elderly MDS patients with pre-existing chromosomal abnormalties; these are associated with improved survival compared with patients in whom the cytogenetically abnormal clone persists. Patients with 'high-risk' chromosomal abnormalities may particularly benefit from this treatment.

Low-dose 5-aza-2'-deoxycytidine, a DNA hypomethylating agent, for the treatment of high-risk myelodysplastic syndrome: a multicenter phase II study in elderly patients

PURPOSE

5-Aza-2'-deoxycytidine (decitabine; DAC) is a DNA hypomethylating agent that has shown a 50% response rate in a small phase II study in elderly patients with high-risk myelodysplastic syndrome. We performed a second, multicenter phase II study in a larger group of patients to confirm our findings and to study the toxicity of DAC.

PATIENTS AND METHODS

Between June 1996 and September 1997, 66 patients (median age, 68 years) from seven centers received DAC 45 mg/m(2)/d for 3 days every 6 weeks. For patients in whom a complete response (CR) was reached after two courses, two further cycles were administered as consolidation therapy. In case of a stable disease situation, improvement, or a partial response (PR), a maximum of six cycles was administered. The primary end points were response rate and toxicity. The secondary end points were response duration, survival from the start of therapy, and overall survival.

RESULTS

The observed overall response rate was 49%, with a 64% response rate in the patients with an International Prognostic Scoring System (IPSS) high-risk score. The actuarial median response duration was 31 weeks, with a response duration of 39 weeks and 36 weeks for patients who reached a PR or CR, respectively. The actuarial median survival time from the time of diagnosis was 22 months and from the start of therapy was 15 months. For the IPSS high-risk group, the median survival time was 14 months. The median progression-free survival time was 25 weeks. Myelosuppression was rather common, and the treatment-related mortality rate was 7% and was primarily associated with pancytopenia and infection. Significant responses were observed with regard to megakaryopoiesis, with increases in platelet counts having already occurred after one cycle of DAC therapy in the majority of the responding patients.

CONCLUSION

We were able to confirm our previous observation that DAC therapy was effective in half of the studied patients with high-risk myelodysplastic syndrome and is especially active in the patients with the worst prognoses. Myelosuppression was the only major adverse effect observed.

Comparison of single and dual-platform assay formats for CD34+ haematopoietic progenitor cell enumeration

Most techniques for CD34+ cell enumeration are dual platform assays. That is, they derive absolute numbers of CD34+ cells from either the flow cytometrically assessed per cent (%) CD34+ cells within the nucleated cells and/or the white blood cell count from a haematology cell analyser. Recently, so-called single-platform assays have been developed, in which the absolute number of CD34+ cells is directly derived from a single flow cytometric measurement. The present study aims to compare the variation between eight laboratories in CD34+ cell counts from paired assays of 15 samples using a common single (ProCOUNT) and the local dual-platform method. Six laboratories used the 'SIHON' and two the 'ISHAGE' protocol for CD34+ cell enumeration. Use of the single-platform method reduced the inter-laboratory variation in per cent and absolute numbers of CD34+ cells, as measured by interquartile ranges, by half but did not lead to an appreciable reduction of the inter-laboratory variation in white blood cell counts. Thus, part of the reduced inter-laboratory variation obtained with ProCOUNT may have been a result of the use of standardized procedures and reagents to detect CD34+ cells. In order to eliminate any variation arising from the use of different local protocols for percentage of CD34+ cell assessments, a comparison was made of the ProCOUNT-derived absolute CD34+ cell numbers (i.e. single platform) with the dual-platform absolute CD34+ cell numbers calculated by multiplying ProCOUNT-derived percentage of CD34+ cells and with the corresponding haematology analyser-derived white blood cell count. Regardless, the interquartile ranges of absolute CD34+ cell numbers remained almost a factor of two smaller with the use of the single platform method. Thus, these results suggest that single-platform methodology can reduce the variation in absolute CD34+ cell numbers between laboratories.

Peripheral blood stem cell transplantation as an alternative to autologous marrow transplantation in the treatment of acute myeloid leukemia?

The clinical use of autologous marrow transplantation in acute myeloid leukemia (AML) has been hampered by the inability to collect adequate numbers of cells after remission induction chemotherapy and the notably delayed hematopoietic regeneration following autograft reinfusion. Here we present a study in which the feasibility of mobilizing stem cells was investigated in newly diagnosed AML. Among 96 AML patients, 76 patients (79%) entered complete remission. Mobilization was undertaken with low dose and high dose schedules of G-CSF in 63 patients, and 54 patients (87%) were leukapheresed. A median of 2.0 x 10(6) CD34+ cells/kg (range 0.1-72.0) was obtained in a median of three leukaphereses following a low dose G-CSF schedule (150 microg/m2) during an average of 20 days. Higher dose regimens of G-CSF (450 microg/m2 and 600 microg/m2) given during an average of 11 days resulted in 28 patients in a yield of 3.6 x 10(6) CD34+ cells/kg (range 0-60.3) also obtained following three leukaphereses. The low dose and high dose schedules of G-CSF permitted the collection of 2 x 10(6) CD34-positive cells in 46% and 79% of cases respectively (P = 0.01). Twenty-eight patients were transplanted with a peripheral blood stem cell (PBSC) graft and hemopoietic repopulation was compared with the results of a previous study with autologous bone marrow. Recovery of granulocytes (>0.5 x 10(9)/l, 17 vs 37 days) and platelets (>20 x 10(9)/l; 26 vs 96 days) was significantly faster after peripheral stem cell transplantation compared to autologous bone marrow transplantation. These results demonstrate the feasibility of PBSCT in the majority of cases with AML and the potential advantage of this approach with respect to hemopoietic recovery.

Use of recombinant GM-CSF during and after remission induction chemotherapy in patients aged 61 years and older with acute myeloid leukemia: final report of AML-11, a phase III randomized study of the Leukemia Cooperative Group of European Organisation for the Research and Treatment of Cancer and the Dutch Belgian Hemato-Oncology Cooperative Group

We conducted a prospective randomized multicenter clinical trial comparing the effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) as an adjunct to intensive chemotherapy in patients of 61 years and older with untreated newly diagnosed acute myeloid leukemia (AML). Patients were randomized to either receive daunomycin-cytosine arabinoside with GM-CSF or daunomycin-cytosine arabinoside (control arm). Based on the rationale that GM-CSF might sensitize the leukemic cells to the cytotoxicity of chemotherapy as well as enhance white blood cell regeneration, GM-CSF was given during chemotherapy as well as after chemotherapy. Patients were treated with one, and in case of a partial response, with two remission induction cycles. When a complete remission was attained they received one additional cycle of consolidation therapy. Of 318 evaluable patients with a median age of 68 years, 157 were randomized to receive GM-CSF and 161 were assigned to control therapy. The effect of GM-CSF on treatment was evaluated according to intention-to-treat. Complete remission was achieved in 56% of the patients in the GM-CSF group and 55% of the control patients (P = .98). Recovery of neutrophils was significantly faster in GM-CSF-treated patients. The median time of recovery of neutrophils towards 0.5 x 10(9)/L was 23 days in the GM-CSF group versus 25 days in the control group (P = .0002) with the percentages of patients who recovered being 81% and 71%, respectively. With a median follow-up of 36 months, the probabilities of survival at 2 years after randomization were estimated at 22% for individuals assigned to the GM-CSF treatment as well as for control patients (P = .55). Disease-free survival at 2 years compared 15% and 19% for the two treatment groups (P = .69). The number of nights spent in the hospital, number of transfusions, and frequencies and types of hemorrhages and infections did not differ either. The cytogenetic results at diagnosis of this study in elderly AML shows that there is a relatively high numerical representation of patients with abnormal cytogenetics (55% of documented cases), who showed significantly inferior response rates and survival duration. We conclude that, except for a faster neutrophil recovery, GM-CSF during and after induction chemotherapy does not improve the clinical outcome of elderly patients with AML.

A randomized phase II study on the effects of 5-Aza-2'-deoxycytidine combined with either amsacrine or idarubicin in patients with relapsed acute leukemia: an EORTC Leukemia Cooperative Group phase II study (06893)

5-Aza-2'-deoxycytidine combined with either amsacrine or idarubicin has been applied in a treatment protocol for patients with a relapse of acute myeloid or lymphocytic leukemia. Sixty-three patients received 5-Aza-2'-deoxycytidine 125 mg/m2 as a 6 h infusion every 12 h for 6 days in combination with either amsacrine 120 mg/m2 as a 1 h infusion on days 6 and 7 (n=30) or idarubicin 12 mg/m2 as a 15 min infusion on days 5, 6 and 7 (n = 33). Twenty-three patients (36.5%) obtained a complete remission (CR); eight of 30 patients treated with amsacrine and 15 of 33 treated with idarubicin. Patients with an interval of more than 1 year between initial diagnosis and start of the protocol achieved CR in 51.4%, compared to 15.4% for patients with an interval of less than 1 year. Patients with normal cytogenetics had a higher CR rate (61%) than those with abnormal cytogenetic findings (15.8%). Digestive tract and hematologic toxicity was prolonged, compared to standard induction schedules. Median disease-free survival was approximately 8 months, with only 20% of patients staying in remission for more than 1 year. 5-Aza-2'-deoxycytidine is a good antileukemic agent with considerable toxicity. Current results merit further investigations in previously untreated leukemia.

Clinical experience with fludarabine and its immunosuppressive effects in pretreated chronic lymphocytic leukemias and low-grade lymphomas

Fludarabine monophosphate (FAMP) is a new adenine nucleoside analogue with a promising efficacy in B-cell chronic lymphocytic leukemia (B-CLL) and low-grade non-Hodgkin lymphomas (NHLs). Here, the clinical experience and side effects with FAMP are reported in 77 patients with pretreated CLL (59 B-CLL, 2 T-CLL) and low-grade NHLs (9 immunocytic lymphomas including 5 Waldenström's macroglobulinaemia, 2 centrocytic (cc) and 5 centroblastic-centrocytic (cb-cc) NHLs). 70/77 patients are evaluable for response. All except 8 patients were pretreated with one to four different regimens and had progressive disease. FAMP was administered at a dosage of 25 mg/m2 daily for 5 days as 30 minute infusion every fifth week. Partial (PR) or complete remission (CR) was achieved in 38/56 (68%) and 3/56 (5%) of evaluable patients with CLL, respectively. In 7/8 (1 x CR, 6 x PR) evaluable patients with immunocytic lymphoma and in 3/6 (3 x PR) patients with cc or cb-cc lymphoma remissions were obtained. The probability of progression-free survival was 66% and the event-free survival was 25% and 22% at 12 and 18 months. The median progression-free survival until relapse or death, however, was only 7 months (2-20+). Major toxic effects included infections in 22 patients (grade 3 and 4 WHO), granulocytopenia (mainly grade 3) and nausea in 8 patients (mainly grade 1). 19/22 patients were in PR at the time of occurrence of infectious complications. Meanwhile, 14 patients died due to septicaemia, pneumonia or other infections. Nine patients developed severe septicaemia, 4 patients had pneumocystis carinii or aspergillus pneumonias. The high infection rate may not only be due to hypogammaglobulinaemia and granulocytopenia induced by FAMP but also to a remarkable decrease of CD4+ cells from a median of 2479 to 241 CD4+ cells/microliters after 6 cycles of FAMP. In one case a tumor lysis syndrome was observed. No CNS toxicity was noted. It is concluded that FAMP is effective even in patients with advanced CLL and low-grade NHLs refractory to multiple chemotherapy regimens. However, FAMP has a marked suppressive effect on granulocytes and T-lymphocytes, predominantly CD4+ lymphocytes.

Differentiation induction of HL60 cells in a long-term bone marrow culture of acute myeloid leukemia

Bone marrow stromal cells are critical for the proliferation and differentiation of hemopoietic stem cells. The hemopoietic microenvironment is reproduced in long term bone marrow culture (LTBMC). Normal LTBMC versus leukemic LTBMC and their stroma conditioned medium were compared with respect to their proliferative and differentiation-inducing capacities. Myeloid leukemic cells (HL60) were layered onto LTBMCs derived from normal volunteers and patients with AML. Differentiation was measured with a comprehensive panel of maturation parameters, i.e. morphology, cytochemistry, quantitative enzyme determination, NBT test and immunophenotyping. Inhibition of proliferation occurred in all cocultures. Clear maturation in monocytic direction was obvious in one culture of HL60 cells layered onto a leukemic stroma. As stroma-derived conditioned medium has no effect, a cellular interaction seems involved. These observations support not only the concept that normal stroma influences leukemic cell growth but also that leukemic stroma can modulate cell growth and maturation.

Low beta-adrenergic receptor concentration on human thymocytes

Several agents are known that can elevate cyclic AMP levels in lymphoid cells, e.g. isoproterenol, PGE1 and adenosine. We have studied the cyclic AMP increasing effect of these agents on thymocytes from mouse and man and on human peripheral T lymphocytes. In contrast to mouse thymocytes and human peripheral T lymphocytes, human thymocytes appeared to be insensitive to isoproterenol, but did respond to PGE1 and adenosine. Furthermore, the density of beta-adrenergic receptors on the cells was determined by measuring the specific binding of 3H-dihydroalprenolol. A correlation was found between the receptor density on the cells and the rise in intracellular cyclic AMP induced by isoproterenol: human thymocytes appeared to have very few beta-adrenergic receptors, in contrast to thymocytes from mouse or to T lymphocytes from human blood. We conclude that the development of beta-adrenergic receptors in T cell ontogeny is different for mice and human beings. Comparison of animal models with the situation in man should be made with caution.

Changes in human T lymphocytes after thymectomy and during senescence

Peripheral lymphocytes from individuals who had been thymectomized in adult life for myasthenia gravis (MG) or for other, nonimmunological reasons showed a moderate decrease in proliferative response capacity to several T-cell mitogens as compared to lymphocytes from normal individuals. The decrease of the response to mitogens and allogeneic lymphocytes was 20-30% within 5 years after thymectomy and about 50% more than 15 years after thymectomy. A comparable decrease in lymphocyte proliferative response capacity was found in healthy aged humans (68-97 years old). Analysis of T lymphocytes from both aged and thymectomized individuals with monoclonal (OKT) antibodies showed a similar pattern: the proportion of T lymphocytes binding OKT6, OKT10, or OKI1 were found. A biochemical parameter for human T-cell differentiation, the lactate dehydrogenase (LDH) isoenzyme pattern, showed a significantly lower H/M ratio in the group of elderly people compared to young individuals. Furthermore, among patients thymectomized for MG, a significant correlation was observed between the LDH isoenzyme pattern of the T lymphocytes and the proliferative response to mitogens of these cells. In contrast, in healthy thymectomized individuals the LDH isoenzyme pattern appeared to be normal. These findings indicate that, after thymectomy or involution of the thymus, at least part of the peripheral blood T lymphocytes have properties different from those of the cells of young individuals. These cells might represent immature and/or not fully differentiated lymphocytes.

Influence of adult thymectomy on immunocompetence in patients with myasthenia gravis

The influence of adult thymectomy on several parameters of immunocompetence in patients with myasthenia gravis (MG) was investigated. Since incomplete thymectomy may lead to the presence of thymic remnants, we determined the activity of a thymus-dependent factor in the sera of the MG patients. As measured by several parameters, MG patients showed a normal immunocompetence compared with healthy controls, except in the response to DNCB sensitization in vivo. When tested at least 5 years after thymectomy, MG patients were found to have decreased response to mitogens, and a decreased cytotoxic T cell response in cell-mediated lympholysis. The response to challenge with DNCB in vivo was decreased both in thymectomized and nonthymectomized MG patients. No difference was found in a) the percentage of circulating T, B, non-B/non-T cells; b) the response to allogeneic cells (MLR); c) the antibody-dependent lymphocytotoxicity; d) the production of immunoglobulins in vitro by pokeweed mitogen-stimulated cells; and e) the anamnestic response to antigens in vitro. We conclude that adult thymectomy results in a decrease in the function of some subpopulations of lymphocytes.

Influence of adult thymectomy on immunocompetence in patients with myasthenia gravis

The influence of adult thymectomy on several parameters of immunocompetence in patients with myasthenia gravis (MG) was investigated. Since incomplete thymectomy may lead to the presence of thymic remnants, we determined the activity of a thymus-dependent factor in the sera of the MG patients. As measured by several parameters, MG patients showed a normal immunocompetence compared with healthy controls, except in the response to DNCB sensitization in vivo. When tested at least 5 years after thymectomy, MG patients were found to have decreased response to mitogens, and a decreased cytotoxic T cell response in cell-mediated lympholysis. The response to challenge with DNCB in vivo was decreased both in thymectomized and nonthymectomized MG patients. No difference was found in a) the percentage of circulating T, B, non-B/non-T cells; b) the response to allogeneic cells (MLR); c) the antibody-dependent lymphocytotoxicity; d) the production of immunoglobulins in vitro by pokeweed mitogen-stimulated cells; and e) the anamnestic response to antigens in vitro. We conclude that adult thymectomy results in a decrease in the function of some subpopulations of lymphocytes.

Experiences with thymosin in primary immunodeficiency disease

Thymosin has no effect in vitro on cyclic AMP levels in thymocytes. However, when thymosin was injected into patients lacking "serum factor" (SF) activity, it induced the appearance of SF or SF-like activity and the disappearance of target cells for SF among the peripheral blood lymphocytes of the treated patients. On the other hand, when thymosin was injected into one patient with normal SF activity, it induced a marked decrease of SF activity and the appearance of target cells for SF among the peripheral blood lymphocytes of this particular patient.

Effect of a human serum thymic factor on hydrocortisone-treated thymocytes

A human serum thymic factors (SF) stimulated cyclic adenosine-3' ,5'-monophosphate (cAMP) synthesis in normal mouse thymocytes. Such stimulation was no longer observed when thymocytes were depleted of hydrocortisone (HC)-sensitive cells. It was concluded that SF selectively stimulate cAMP in HC-sensitive cells. Furthermore, incubation of thymocytes with SF enlarged the population of HC-resistant thymocytes. These results suggest that SF might act on HC-sensitive thymocytes increasing their cellular cAMP level and inducing their transformation in HC-resistant cells.

Thymosin-induced human serum factor increasing cyclic AMP

Thymosin has virtually no in vitro effect on cyclic AMP levels in thymocytes and seems not to react with either the beta-adrenergic receptor or with the putative human serum thymic factor (SF) receptor. However, when thymosin is injected into patients lacking SF activity, it induces the appearance of a serum factor which increases cellular cyclic AMP levels in thymocytes in vitro. This factor appears to act on a membrane site distinct from the beta-adrenergic receptors.