Heterogeneity of peripheral blood T-cell colony-forming cells in patients with T-cell malignancies

Some peripheral blood clonogenic T-cells from patients with T-cell malignancies can generate colonies in methylcellulose in the absence of added growth factors or mitogen stimulation (T-CFC_S). T-CFC from these patients were also able to form colonies in semi-solid media in the presence of added growth factors (T-CFC_i. T-CFC_S, in contrast to T-CFC_i, were highly clonogenic cells possessing self-renewal capacity in the absence of added growth factors. T-CFC₅ were in cell cycle and more sensitive to Ara-C or ADM (D₁₀ = 0.009 and 0.025 μg/ml respectively) than T-CFCi (D₁₀ = 1 and 2 μg/ml respectively). Furthermore, T-CFC₅ were more radiosensitive (D_o < 1.1 Gy) than T-CFC. (D_o <5 Gy). T-cell precursors from patients with immature blast cells (E⁻, OKT3⁻, OKT6⁺, OKT10⁺) were independent of added growth factors for their in vitro proliferation whereas in cases with mature blast cells (E⁺, OKT3⁺) T-CFC were significantly more dependent. These observations strongly suggest that T-CFC₅ and T-CFC_i represent different cell subsets.

The phenotype of pooled induced and spontaneous T-cell colonies was highly individualized. However, colonies contained a significant proportion of relatively immature T-cells as assessed by the proportion of OKT6⁺, OKT10⁺, OKT3⁺ and E⁺ cells. The phenotype of colony cells was quite similar to that observed on fresh leukemic cells suggesting a defect of the in vitro differentiation of both T-CFC₅ and T-CFC_i.     

T-cell colony formation in patients with T-cell malignancies: growth factor requirements for in-vitro proliferation of peripheral blood T-cell colony-forming cells

Peripheral blood T colony-forming cells (T-CFC) from patients with T-cell malignancies are capable of proliferation in methylcellulose, in the absence of added growth factors or mitogenic stimulation. We show here that based on the spontaneous plating efficiencies of their T-CFC, two groups of patients can be established: Group A (10 patients) with a high colony number (more than 100 colonies/10(5) seeded cells), and group B (12 patients) with less than 100 colonies/10(5) cells. The addition of interleukin 2-(IL2) containing PHA-leukocyte conditioned medium enhanced colony growth from group B but not group A patients. Moreover, both biochemically purified and recombinant IL2 induced the colony growth from group B but not group A patients without any other stimulation. In addition, a monoclonal antibody (moAb) against the IL2 receptor (IL2-R; anti-Tac) inhibited the spontaneous colony formation from T-CFC of both groups of patients. These observations strongly suggest that IL2-R are involved in the spontaneous colony growth of T-CFC. To determine whether IL2 is also involved in the spontaneous colony formation, media conditioned (LCM) by unstimulated leukemic cells were tested for IL2 activity. A constitutive release of IL2 was detected in LCM from only 2 out of 10 patients tested, and some of them were capable to inhibit thymidine incorporation by IL2-dependent cells cultured in the presence of highly purified IL2. However, most of these LCM contained a T-cell colony-promoting activity (TCPA) inducing colony formation from both normal resting and PHA-stimulated E+ clonogenic cells without added IL2 or mitogenic stimulation. TCPA-containing LCM induced the expression of functional IL2-R and IL2 release by normal resting lymphocytes. TCPA was constitutively released by blast-enriched cell fractions suggesting that it is released by the leukemic cells.     

卵巢恶性肿瘤患者细胞免疫状免疫状态的研究及临床价值：COKT McAb...

Blood samples from 79 subjects (27 cases of ovarian malignancy, 2 ovarian borderline epithelial tumor, 38 benign gynecologic disease and 12 healthy women) were measured for peripheral blood T-cell subsets using monoclonal antibodies and SPA-Ig rosette technique. It was found that in patients with ovarian malignancy, the percentage of OKT4+ cells was significantly reduced whereas the percentage of OKT8+ cells was markedly increased as compared with those in the healthy women and patients with benign gynecologic disease; OKT4/OKT8 ratio declined obviously; which were more pronounced in patients with advanced or recurrent tumor.     

Interleukin 2 activity in peripheral blood mononuclear cells of patients with gynecologic malignancies

We studied production of, absorption of and response to interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMC) from 66 patients with gynecologic malignancies, in addition to measurement of the OKT 4/OKT 8 cell ratio. Patients with benign tumor served as controls. The OKT 4/OKT 8 cell ratio in patients with advanced (but not early) gynecologic malignancies was significantly lower than that in patients with benign tumor. PBMC from advanced cancer patients activated with phytohemagglutinin (PHA) had significantly lower IL-2 production compared to that from patients with benign tumors, while significant changes in their ability to respond to IL-2 and to absorb IL-2 were not observed. Absolute numbers of OKT 8 positive cells in PBMC of patients with good prognosis were significantly decreased after surgery and chemotherapy, while those of OKT 4 positive cells remained unchanged. Although IL-2 production in PBMC of patients with good prognosis was significantly elevated after chemotherapy, that in PBMC of patients with poor prognosis declined to about a half of pre-operative levels. The ability of PBMC to respond to IL-2 was significantly elevated not only in patients with good prognosis but also in patients with poor prognosis after termination of chemotherapy. On the other hand, the ability of PBMC to absorb IL-2 remained unchanged during the course of treatment. These findings may contribute to the understanding of tumor-induced immune suppression.     

Interleukin 2 activity in peripheral blood mononuclear cells of patients with gynecologic malignancies

We studied production of, absorption of and response to interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMC) from 66 patients with gynecologic malignancies, in addition to measurement of the OKT 4/OKT 8 cell ratio. Patients with benign tumor served as controls. The OKT 4/OKT 8 cell ratio in patients with advanced (but not early) gynecologic malignancies was significantly lower than that in patients with benign tumor. PBMC from advanced cancer patients activated with phytohemagglutinin (PHA) had significantly lower IL-2 production compared to that from patients with benign tumors, while significant changes in their ability to respond to IL-2 and to absorb IL-2 were not observed. Absolute numbers of OKT 8 positive cells in PBMC of patients with good prognosis were significantly decreased after surgery and chemotherapy, while those of OKT 4 positive cells remained unchanged. Although IL-2 production in PBMC of patients with good prognosis was significantly elevated after chemotherapy, that in PBMC of patients with poor prognosis declined to about a half of pre-operative levels. The ability of PBMC to respond to IL-2 was significantly elevated not only in patients with good prognosis but also in patients with poor prognosis after termination of chemotherapy. On the other hand, the ability of PBMC to absorb IL-2 remained unchanged during the course of treatment. These findings may contribute to the understanding of tumor-induced immune suppression.     

Adenosine deaminase activity in peripheral blood cells of patients with haematological malignancies.

Adenosine deaminase (EC 3.5.4.4, ADA) has been assayed in lymphocytes, granulocytes and erythrocytes from 45 patients with haematological malignancies. Activities were uniformly low in lymphocytes from patients with chronic lymphocytic leukaemia. Variable, but abnormal activities were frequently found in multiple myeloma, untreated lymphoma and leukaemic reticuloendotheliosis. High values were observed in lymphocytes from patients with lymphoma during intensive combination chemotherapy. ADA levels in lymphocytes were not correlated with levels in granulocytes or erythrocytes. ADA was elevated in blasts of patients with acute lymphocytic and myelogenous leukaemias but the ranges of activities per cell were so similar that ADA assay is unlikely to be of major help in distinguishing the two diseases.     

Simultaneous presence of EBNA-positive and colony-forming cells in peripheral blood of patients with infectious mononucleosis.

EBNA-positive lymphoblast cells were detected in 0.1 to 0.9% of the T-cell-depleted lymphocytes obtained from peripheral blood samples of five patients with infectious mononucleosis (IM). The same blood specimens from four of the five patients contained cells that formed EBNA-positive colonies in soft agar containing EBV antibodies. The ratio of the colony formers to EBNA-positive cells was higher in blood samples taken early in the disease than in those obtained in later stages of the disease. The present results strongly suggest that EBV-transformed cells are present in the peripheral circulation of IM patients and that such cells can directly give rise to immortalized cell lines in vitro.     

Factors influencing the collection of peripheral blood stem cells in patients with acute myeloblastic leukemia and non-myeloid malignancies

Factors influencing the collection of autologous peripheral blood stem cells (PBSCs) were studied in 182 mobilization procedures performed on 145 consecutive patients with acute myeloblastic leukemia (AML; n=67) and with various non-myeloid malignancies (NMM; n=78). PBSC were collected following mobilization with chemotherapy, treatment with granulocyte colony-stimulating factor (G-CSF) or chemotherapy plus G-CSF. Fewer colony-forming unit granulocyte-macrophages (CFU-GMs) were collected from patients with AML than from patients with NMM (P<0.0001), although there were no differences in the numbers of CD34+ cells collected between both groups. Multiple regression analysis showed that chemotherapy alone was predictive of a low CD34+ yield in patients with NMM (regression coefficient (RC)=-2.1; P=0.003). In addition, the interactions "diagnosis mutliple myeloma (MM)xmobilization with chemotherapy" (RC=2.9; P=0.004) and "diagnosis MMxmobilization with chemotherapy plus G-CSF" (RC=2.1; P=0.04) also remained in the model, both showing a favorable influence. In AML, mobilization with chemotherapy plus G-CSF was associated with higher CD34+ yields (P=0.003). In this subgroup of patients, multiple regression analysis identified the number of cycles of previous chemotherapy (< or =2 cycles; RC=1.3; P=0.03) and peripheral blood counts (WBC > or =1.5 x 10(9)/l and monocytes >20%; RC=0.8; P=0.02) as the factors most predictive of CD34+ cell yield. These findings emphasize the need to optimize harvesting technique to enhance safety and minimize morbidity and costs of this valuable procedure.     

高龄血液恶性肿瘤患者自体外周血造血干细胞动员采集的临床研究

目的探讨高龄血液恶性肿瘤患者外周血干细胞动员采集的疗效及影响因素。方法对32例高龄患者和57例中青年患者经化疗＋生长因子动员后,使用CS3000Plus血细胞分离机（Baxter公司）进行外周血干细胞采集,并进行临床观察和分析。结果所有病例均采集成功。高龄患者动员获得单个核细胞（MNC）数为（6．47±7．04）×10^9／L,中青年患者获得MNC数为（10．89±9．50）×10^9／L,差异有显著性。高龄患者采集获得的MNC及CD34^＋细胞分别为（5．24±1．05）×10^8／kg和（2．74±1．04）×10^6／kg,中青年患者采集获得MNC及CD34^＋细胞分别为（6．71±2．62）×10^8／kg和（4．82±2．62）×10^6／kg,差异具有显著性。高龄患者在采集过程中不良反应发生率明显高于中青年患者。高龄患者与中青年患者移植后造血重建时间相当。结论做好采集前的充分准备,注意并发症的预防和处理,一般会成功地动员采集高龄患者自体外周血造血干细胞。     

Accessory role of autologous T lymphocytes and adherent cells for the in vitro proliferation of T-cell colony-forming cells from patients with T-cell acute lymphoblastic leukemia

Peripheral blood T colony-forming cells (T-CFC) from patients with T-cell malignancies can proliferate in methylcellulose in the absence of added growth factors or mitogenic stimulation. Mononuclear cells (MNC) from 7 patients with T-cell acute lymphoblastic leukemia were separated into cells forming rosettes with sheep erythrocytes (E+) or not (E-). E- cells were further depleted by complement-mediated cytotoxicity with OKT3 monoclonal antibody (E-OKT3- cells). The study of their spontaneous T-cell colony-forming ability suggested that proliferation of T-CFC in the absence of added growth factors requires cellular cooperation because: (1) No colony growth was observed at low cell concentrations (up to 2 X 10(4) cells/ml) whereas at higher cell densities the number of colonies increased exponentially; (2) The plating efficiency from unfractionated MNC was higher than that from E-OKT3- or E+ cells. Irradiated autologous E+ cells enhanced the plating efficiency from blast-enriched cell fractions (E-OKT3-) when co-cultured either directly in methylcellulose or separately in a two layer assay (agar-methylcellulose), suggesting that their activity could be due to diffusible factors; (3) Adherent-cell depletion of MNC decreased colony formation. Autologous irradiated adherent cells were able to restore the plating efficiency from MNCA- cells when co-cultured directly in methylcellulose but not in separate layers; however, media conditioned by patients' A+ cells could enhance the colony growth from patients' MNCA- cells, indicating that their activity could also be mediated by constitutively released soluble factors.     

Prognostic value of T-cell receptor gamma rearrangement in peripheral blood or bone marrow of patients with peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCL) have a variable outcome. We have investigated the prognostic value of molecular staging in non-anaplastic PTCL. T-cell receptor gamma rearrangements were routinely determined in peripheral blood (n = 40) and bone marrow (n = 38) of patients with PTCL (75% unspecified) by conventional PCR at diagnosis. Tissue controls for PCR included 24 tumour biopsies. Twenty-four patients (60%) had a PCR-detectable clonal TCR gamma rearrangement in PB or BM. These TCR gamma PCR positive patients had significantly more stage IV disease (14 patients of 15 patients; P = 0.001), elevated LDH (14 of 18 patients; P = 0.04), higher IPI (16 of 21 patients; P = 0.03), more anemia (15 of 19 patients; P = 0.02) and lower platelet counts (seven of seven patients; P = 0.02). Clinical outcome of this clonal group was characterised by lower complete remission rates (37.5% vs. 62.5%), and overall response rates (58.3% vs. 87.5%; P < 0.05) as well as a significantly shorter median overall survival (12.8 vs. 30.0 months; P = 0.006). Patients with clinical stages I - III but molecular stage IV had an equally poor overall survival when compared with patients with clinical stage IV (15.8 vs. 13.9 months). In contrast, patients with CS I - III in the absence of a TCR gamma rearrangement in PB or BM had a favourable outcome with an estimated overall survival of 70% at 3 and 5 years. Molecular staging in PB and BM by TCR gamma PCR at diagnosis may serve as a useful prognostic tool in PTCL.     

Interleukin-2 activity and the response of peripheral blood lymphocytes in patients with gynecologic malignancies

The interleukin-2 (IL-2) production in peripheral blood lymphocytes (PBL), the response to IL-2, and the IL-2 absorption by PBL was studied in 34 patients with gynecologic malignancies. In addition measurement of the OKT 4/8 cell ratios were made. The OKT 4/8 cell ratio in patients with advanced gynecologic malignancies was significantly lower than that in patients with benign tumor. PBL from advanced cancer patients activated by phytohemagglutinin (PHA) had significantly lower IL-2 productivity than that from patients with benign tumors, while no significant difference was observed in its abilities to respond to IL-2 and to absorb IL-2. The OKT 4/8 cell ratio and IL-2 productivity in PBL of patients with good prognosis were significantly elevated after chemotherapy. On the other hand, PBL of patients with poor prognosis declined to about one-half of the preoperative levels. Although in patients with good prognosis the ability of PBL to respond to IL-2 was not changed before and after treatment, in patients with poor prognosis the response was significantly increased after chemotherapy. However, the ability to absorb IL-2 was not affected by treatment.     

自体外周血造血干细胞移植治疗外周T细胞淋巴瘤的临床研究

目的 探讨自体外周血造血干细胞移植对外周T细胞淋巴瘤的治疗效果的影响.方法 选取收治的191例非霍奇金淋巴瘤患者,其中外周T细胞淋巴瘤67例,符合入组条件的60例纳入研究.依据随机数字表法将患者分为治疗组及对照组各30例,治疗组患者给予常规化疗联合自体外周血造血干细胞移植后大剂量放化疗进行治疗,对照组患者给予常规化疗方案进行治疗.统计比较两组患者的血象恢复时间、疗效、生活质量情况、不良反应、生存情况.结果 治疗组患者中性粒细胞恢复≥1.5×109/L及血小板恢复≥20×109/L的时间分别为(11.63±2.86)d和(15.24±2.49)d;治疗组患者治疗过程中出现发热例数多于对照组患者,差异有统计学意义(P﹤0.05);治疗组患者生存时间和无进展生存时间均长于对照组患者,差异有统计学意义(P﹤0.05);治疗组患者的生活质量优于对照组患者,差异有统计学意义(P﹤0.05).结论 自体外周血造血干细胞移植有效提高外周T细胞淋巴瘤疗效的同时还对患者的生活质量有改善作用,延长患者生存时间和无进展生存时间,移植后有部分患者出现发热,经对症处理可缓解.     

Colony-stimulating and colony-forming cells in peripheral blood as prognostic markers in acute myelogenous leukemia.

Colony-forming cells (CFC) and colony-stimulating activity (CSA) in peripheral blood cells have been studied before and repeatedly during treatment of 32 patients with acute myelogenous leukemia. WBC obtained after Isopaque-dextran separation were cultured in vitro by a double-layer agar technique. Before treatment 19 patients out of 32 had CSA and all had CFC; both CSA and CFC were found in 19 patients. In follow-up studies during treatment, CSA was mainly unaffected during the leukopenic phase, while CFC were suppressed. No CFC were found at WBC counts below 1,000/mm3. This seems to imply that CFC are more sensitive to chemotherapy than colony-stimulating cells. 14 patients entered remission; all of them had CSA. 16 out of the 18 nonresponders lacked on or both types of cells. The presence of CSA and CFC in peripheral blood therefore appears to be a sign of favorable prognosis, while the absence of CSA and/or CFC implies lack of response to treatment. The conclusion from this study is that the presence of both CFC and CSA in peripheral WBC is a sign of a good prognosis. Absence of CFC and/or CSA in the initial sample indicates that the patient is unlikely to respond to conventional therapy with cytotoxic drugs. The presence or absence of CSA alone has a higher prognostic significance than the presence or absence of CFC.     

Prophylactic growth factor-primed donor lymphocyte infusion using cells reserved at the time of transplantation after allogeneic peripheral blood stem cell transplantation in patients with high-risk hematologic malignancies

BACKGROUND: Standard allogeneic bone marrow transplantation (BMT) offers only a small chance of cure for most adult patients with advanced hematologic malignancies. The authors postulated that allogeneic peripheral blood stem cell transplantation (PBSCT) followed by prophylactic growth factor-primed donor lymphocyte infusion (DLI) with cells reserved at harvest would maximize the graft-versus-tumor effects in patients with hematologic malignancies who had a high risk of recurrence. METHODS: Seventeen patients with hematologic malignancies who had a high risk of recurrence were allocated on an intent-to-treat basis to allogeneic PBSCT from human leukocyte antigen-matched sibling donors followed by prophylactic growth factor-primed DLI of cells reserved at harvest for transplantation. RESULTS: The median age was 37 years (range, 19-56 years). All donors underwent two or more apheresis procedures. The median numbers of mononuclear cells (MNCs), CD34 positive (CD34+) cells, and CD3+ cells, respectively, that were collected for 17 donors were 9.0 x 10(8) MNCs/kg (range, 4.9-14.4 x 10(8) MNCs/kg), 13.0 x 10(6) CD34+ cells/kg (range, 2.4-75.2 x 10(6) CD34+ cells/kg), and 5.8 x 10(8) CD3+ cells/kg (range, 3.3-9.9 x 10(8) CD3+ cells/kg) for a mean number of 2.35 apheresis procedures (range, 2.0-4.0 procedures). The median numbers of MNCs and CD3+ cells that were cryopreserved were 2.1 x 10(8) MNCs/kg (range, 0.0-4.4 x 10(8) MNCs/kg) and 1.4 x 10(8) CD3+ cells/kg (range, 0.0-3.5 x 10(8) CD3+ cells/kg). Seven of 17 patients received additional PBSCs, with a median of 5.0 x 10(7) CD3+ cells/kg (range, 3.0-9.9 CD3+ cells/kg) between Day 41 and Day 120. The reasons for inability to administer additional PBSCs in 10 patients included early death (n = 4 patients), severe graft-versus-host disease (GVHD) (n = 3 patients), disease recurrence (n = 2 patients), and harvest failure (n = 1 patient). Of seven patients, two patients died of recurrence, and one died of cytomegalovirus pneumonitis. The surviving four patients were free of disease when last assessed (median follow-up, 597 days) but were suffering from chronic GVHD (one patient had limited GVHD, and three patients had extensive GVHD). CONCLUSIONS: The authors suggest that allogeneic PBSCT with prophylactic growth factor-primed DLI may be a potentially curative strategy for the treatment of hematologic malignancies in patients with a high risk of recurrence. Their approach may offer the additional advantage of collecting enough cells at harvest for the potential use of DLI, which is easy, convenient for donors, and cost effective.     

Rapid engraftment after allogeneic transplantation of density-enriched peripheral blood CD34+ cells in patients with advanced hematologic malignancies.

BACKGROUND: Acute graft versus host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Preclinical studies have suggested that a T-cell subset with a CD4-/CD8- double-negative (DN) T-cell phenotype is capable of suppressing GVHD. Double-negative T cells can be mobilized into the peripheral blood with granulocyte colony-stimulating factor (G-CSF) and enriched by density centrifugation. The current study was performed to study the feasibility and safety of applying a density gradient separation technique for enrichment of CD34+ and DN T cells, while depleting CD4+ and CD8+ single-positive (SP) T cells from peripheral blood progenitor cells (PBPCs) for the purpose of allogeneic transplantation. METHODS: Twenty-five patients with advanced hematologic malignancies were treated with a myeloablative preparative regimen consisting of fractionated total body irradiation, etoposide, and cyclophosphamide. Human leukocyte antigen identical donors were mobilized with G-CSF PBPC collected by apheresis. The apheresis product was applied to a single-step density gradient, and the low-density cell population was collected. The low-density cell population was infused as the sole source of allogeneic cells after myeloablative therapy. Graft versus host disease prophylaxis consisted of cyclosporine with or without prednisone. RESULTS: CD34 cell recovery was efficient with a median 72% yield, providing for a median CD34+ cell dose of 6.5 x 10(6)/kg (range,1.0- 13.9 x 10(6)/kg). CD3+CD4+ or CD3+CD8+ SP T cells were depleted by a median of 94.4% (range, 58.8- 99.2%), and the ratio of CD34+:SP T cells increased 10-fold. Double-negative T cells were depleted by 92% (range, 18.8- 99.4%), thus the ratio of DN:SP T cells increased less than 2-fold in 71% of apheresis samples tested. Hematopoietic engraftment was rapid, and there was no occurrence of graft failure in examinable patients. Median time to absolute neutrophil count greater than 0.5 x 10(9)/L and platelet count greater than 20 x 10(9)/L was 10.5 and 12 days, respectively. The incidence of Grade 2-4 acute GVHD was 26% (95% confidence interval [CI], 6-45%), although not all patients were examinable due to an unexpectedly high nonrecurrence mortality that at Day 180 was 62% (95% CI, 40-83%). CONCLUSIONS: These data suggest that T-cell subset manipulation via density gradient separation is a safe procedure and allowed rapid hematopoietic recovery. Selective enrichment of a donor DN T-cell subset was observed in only a few and was not associated with a reduced incidence of GVHD. However, the low-density selected cells still resulted in GVHD, and there was a high treatment-related mortality.     

The ratio between CD4+ and CD8+ cells in the peripheral blood of patients with hematological malignancies is not altered by thalidomide

Thalidomide is thought to have anti-angiogenic and immunomodulatory properties, including suppression of tumor necrosis factor-alpha, effects on interleukins and interferons, down-regulation of some cell adhesion molecules, and changes in the proportion of lymphocyte subsets. It is unclear whether the clinical response to thalidomide in patients with multiple myeloma (MM), idiopathic myelofibrosis (IM), and myelodysplastic syndromes (MDS) is related to its ability to inhibit angiogenesis or its immunomodulatory effects. We examined the effect of thalidomide on T-lymphocyte subsets in 18 patients with MDS, 6 patients with MM, 4 patients with IM, and 3 patients with angioimmunoblastic lymphoma (AILD). These patients had either a relapse or progressive disease following cytotoxic chemotherapy including high-dose chemotherapy with autologous stem cell support. Thalidomide was first administered at 100 mg/day p.o. and increased to 400 mg/day. T-lymphocyte subsets (CD4 + , CD8 + ) were measured by fluorescence-activated cell sorter (FACS) before and during treatment with thalidomide. Twenty-six of 31 patients responded to thalidomide, most of them achieving partial remission. The median concentration of CD4 + cells was 443/μl, the median of CD8 + cells was 359/μl (CD3 992/μl). In our cohort, no significant changes in absolute numbers or proportions of CD3 + (P = 0.12), CD4 + (P = 0.668), or CD8 + (P = 0.143) cells were observed following the treatment with thalidomide. Although the CD4/CD8 ratio declined from 1.6 to 1.0 during 3 months of thalidomide treatment, this had no statistical significance (P = 0.1). Our findings show that an effect of thalidomide on the T lymphocytes studied is unlikely to be of major importance for the clinical effects.