骨髓增生异常综合征和再生障碍性贫血患者T淋巴亚群及CD34阳性细胞的研究

目的：对骨髓增生异常综合征（MDS）和再生障碍性贫血（AA）患者的外周血T淋巴细胞亚群、NK细胞及骨髓CD34阳性细胞占单个核细胞（MNC）的比率进行测定,探讨两者细胞免疫异常及骨髓CD34阳性细胞与发病机制的关系。方法：用流式细胞术（FCM）对15例MDS患者,11例AA患者,12例正常对照组T淋巴细胞亚群、NK细胞及CD34阳性细胞占MNC的比率进行测定。结果：MDS患者外周血CD3＋T、CD4＋ T、CD8＋T淋巴细胞均较正常人组明显降低,CD4＋/CD8＋倒置。NK细胞CD16＋56也较正常人组低。AA患者CD4＋ T淋巴细胞稍低于正常人组,但CD8＋T淋巴细胞明显升高,表现为CD4＋/CD8＋也倒置。NK细胞正常。MDS患者CD34＋占骨髓MNC的比率明显高于正常组,AA患者骨髓MNC的比率低于正常组。结论：MDS和AA患者均存在免疫功能状态紊乱,二者的发病机制不同。CD34＋率的测定有助于二者的鉴别诊断,同时是判断MDS预后的简便、可靠的方法。     

再生障碍性贫血雄激素受体与T细胞亚群的变化

目的:检测慢性再生障碍性贫血(CAA)患者骨髓单个核细胞(MNC)雄激素受体(AR)以及骨髓中T细胞亚群水平,探讨AR在CAA免疫病理机制中的作用。方法:①免疫细胞化学SP法检测CAA患者骨髓MNC内AR的表达水平;②流式细胞术检测CAA骨髓中T细胞亚群(CD3 CD4 细胞、CD3 CD8 细胞)的含量。结果:①CAA患者骨髓MNC中AR阳性水平[(35．18±8．78)个／200个MNC]显著低于对照组[(48．46±9．82)个／200个MNC];不同性别间AR的含量差异无统计学意义。②CAA患者骨髓中的CD3 CD8 细胞含量为(28．54±7．57)％,显著高于对照组。③CAA患者骨髓中的AR阳性水平与骨髓中的CD3 CD8 细胞呈负相关(r=-0．576,P<0．01);而与CD3 CD4 细胞含量未见明显的直线相关关系。结论:CAA患者骨髓AR的表达减少,从而使雄激素刺激造血的作用减弱。患者AR的表达与CD3 CD8 细胞含量呈明显负相关,表明AR的异常可能在一定程度上参与了CAA发病机制中的细胞免疫。     

TNF-alpha and IFN-gamma are overexpressed in the bone marrow of Fanconi anemia patients and TNF-alpha suppresses erythropoiesis in vitro

In Fanconi anemia (FA) C mice tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) have key roles in the pathogenesis of bone marrow failure. In FA subjects TNF-alpha was found to be increased in the serum and overproduced by patient-derived B-cell lines. In acquired aplastic anemia, a disease in which, similarly to FA, marrow failure occurs, TNF-alpha and IFN-gamma act as late mediators of the stem cell damage and are overexpressed in patient marrow lymphocytes. This study evaluated in marrow mononuclear cells (MNCs) of patients with FA, the expression of negative modulators of the hematopoiesis, such as TNF-alpha, IFN-gamma, macrophage inflammatory protein 1alpha (MIP-1alpha), and surface Fas ligand, and the role of TNF-alpha on FA erythropoiesis in vitro. TNF-alpha and IFN-gamma were significantly overexpressed in stimulated marrow MNCs of FA patients as compared to healthy controls. MIP-1alpha and Fas ligand were undetectable in patients and controls. In bone marrow cultures, the addition of anti-TNF-alpha increased the size and significantly increased the number of erythroid colony-forming units and erythroid burst-forming units grown from FA patients but not from healthy controls. This indicates that FA subjects have a marrow TNF-alpha activity that inhibits erythropoiesis in vitro. TNF-alpha has a relevant role in the pathogenesis of erythroid failure in FA patients.     

再生障碍性贫血患者联合免疫治疗前后IL-8表达水平的改变

目的:观察急性和慢性再障患者联合免疫疗法治疗前、后外周血和骨髓中白细胞介素8(IL-8)的含量变化和临床意义,并探讨其对监测再障疗效的可行性。方法:应用实时定量PCR和ELISA法检测外周血和骨髓IL-8的含量,流式细胞术分析外周血中CD4/CD8阳性细胞比值变化。结果:急性和慢性再障患者外周血和骨髓中IL-8含量均远高于正常对照者,且CD4/CD8出现倒置。抗淋巴细胞球蛋白(ALG)加环孢素A(CsA)加雄激素较CsA加雄激素治疗效果明显,总有效率分别为83.3%和62.5%。ALG加CsA加雄激素治疗重症再障较CsA加雄激素疗效显著。细胞因子水平改变和疗效明显相关。实时定量PCR和ELISA法正相关,但前者较易测出和量化。结论:ALG联合CsA治疗急、慢性再障疗效显著。细胞因子IL-8可以作为急、慢性再障的疗效监测指标。     

Hepatitis-associated aplastic anemia preceded by a hemophagocytic syndrome-like state

A 21-year-old man was admitted to our hospital for acute hepatitis of unknown cause. His liver function improved with rest, but worsened 2 months later. He developed a high fever and pancytopenia. The serum level of cytokines including TNF-alpha, IFN-gamma, IL-6, and M-CSF was elevated, and hemophagocytes were seen in bone marrow. These findings suggested a hemophagocytic syndrome-like state. With prednisolone, gamma-globulin, and G-CSF, the high fever disappeared and the patient's liver function gradually recovered. However, the severe pancytopenia persisted. The bone marrow became acellular with a small number of hemophagocytes, and hepatitis-associated aplastic anemia was diagnosed. After immunosuppressive therapy with ATG, CyA and G-CSF was started, and the patient showed hematopoietic reconstitution. The bone marrow CD4+/CD8+ lymphocyte ratio recovered to within the normal range, and the serum cytokines including TNF-alpha and IFN-gamma decreased. The increase in serum cytokines, particularly TNF-alpha and INF-gamma, as well as the presence of activated T cells associated with the preceding hemophagocytic syndrome-like state may have predisposed this patient to aplastic anemia.     

In vitro effects of interferon-gamma and tumor necrosis factor-alpha on CD34+ bone marrow progenitor cells from aplastic anemia patients and normal donors

Acquired aplastic anemia is characterized by loss or dysfunction of hematopoietic stem and progenitor cells. The proinflammatory cytokines Tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) may be responsible for the immune-mediated pathology observed in some patients. The CD34+ population of bone marrow mononuclear cells contains primitive cells responsible for hemopoiesis. We investigated the response of CD34+ cells from aplastic anemia patients to a combination of IFN-gamma and TNF-alpha, and compared them to cells from normal volunteer donors. This was to determine whether aplastic CD34+ cells are more sensitive than normal cells to IFN-gamma/TNF-alpha-mediated effects, and whether cytokine-induced CD95 expression can explain the high levels of apoptosis observed in CD34+ cells from aplastic patients. CD34+38- cells were most affected by overnight incubation with these cytokines, their proportion and numbers being reduced in both normal donors and patients. There was no evidence for increased apoptosis, suggesting that this effect may be due to differentiation. IFN-gamma/TNF-alpha induced upregulation of CD95 on both normal and aplastic CD34+ cells, although the basal level of CD95 expression was increased in aplastic cells. However, CD95 induction did not make cells from normal donors or aplastic anemia patients susceptible to induction of apoptosis by agonistic anti-CD95 antibodies, soluble CD95 ligand, or membrane-bound CD95L. In vivo CD95L is required for CD95 induced apoptosis. No forms of this protein were detectable in lymphocytes from aplastic patients. We conclude that increased apoptosis in aplastic CD34+ cells is not due to increased sensitivity to IFN-gamma/TNF-alpha. We further show that normal and aplastic CD34+ cells are resistant to CD95 apoptosis, even in the presence of mCD95L.     

Analysis of T-cell repertoire and mixed chimaerism in a patient with aplastic anaemia after allogeneic bone marrow transplantation

We analysed 26 T-cell receptor (TCR) beta chain subfamilies (VB) of a patient with aplastic anaemia (AA) who underwent allogeneic bone marrow transplantation (allo-BMT). The patient developed pancytopenia at d 80. The patient's T cells were skewed in 10 of 26 TCR-VB on d 83. These TCR-VB, especially VB15, which were almost entirely CD8-positive cells, were skewed throughout her clinical course. Chimaerism analysis of the CD8-positive cells indicated that they were of recipient origin. Therefore, some immune responses induced by the recipient CD8-positive T cells had an important role in pancytopenia in AA patients after allo-BMT.     

CD8+ T cells suppress autologous megakaryocyte apoptosis in idiopathic thrombocytopenic purpura

To investigate the effect and mechanism of the CD8⁺ T cells in bone marrow on autologous megakaryocytopoiesis in idiopathic thrombocytopenic purpura (ITP) patients, we prepared bone marrow mononuclear cells (MNCs) from 15 chronic ITP patients and 13 controls. MNCs were cultured in vitro directly (MNC group) or after depleting CD8⁺ T cells (CD8⁺ T-dep group) or adding purified autologous CD8⁺ T cells to CD8⁺ T-dep MNCs (Coculture group) or adding dexamethasone to the coculture (DEX group) all in semi-solid and liquid culture systems. The quantity and quality of megakaryocytes were measured. The megakaryocyte count was increased in the presence of autologous CD8⁺ T cells of patients with chronic ITP, while platelet production was reduced. In addition, lower percentages of polyploidy and apoptotic megakaryocytes, and higher levels of soluble Fas (sFas) in supernatant were observed. Dexamethasone successfully corrected this effect of CD8⁺ T cells on autologous megakaryocytopoiesis. These studies provide evidence that activated CD8⁺ T cells in bone marrow of patients with chronic ITP might suppress megakaryocyte apoptosis, leading to impaired platelet production. Megakaryocyte apoptosis would be a novel target for the management of ITP.     

T-cell suppression mediated by mesenchymal stem cells is deficient in patients with severe aplastic anemia

OBJECTIVE: To compare the suppressive effect of mesenchymal stem cells (MSC), derived from normal individuals or severe aplastic anemia patients (SAA), on T-cell activation. PATIENTS AND METHODS: We studied bone marrow MSC from 19 healthy donors and 23 SAA patients in different phases of the disease: at diagnosis (n = 3), following immunosuppressive therapy (IS) (n = 16), or after a bone marrow transplant (BMT) (n = 4). MSC were tested for T-cell suppression in the following assays: mixed lymphocyte reaction (MLR), phytohemaglutinin (PHA)-primed cultures, activation surface markers, gamma-IFN production, hematopoietic colony formation (CFC), production of cyclic ADP-ribose (cADPR). RESULTS: The abnormalities of SAA MSC included: 1) significantly lower suppression of T-cell proliferation induced by alloantigens (p = 0.009) or PHA (p = 0.006); 2) impaired capacity to suppress CD38 expression on PHA-primed T cells (p = 0.001); 3) impaired ability to suppress gamma-IFN production in PHA cultures, resulting in an 11-fold higher gamma-IFN concentration; 4) no preventive effect on T cell-mediated inhibition of CFC; and 5) significantly reduced (p = 0.009) production of cADPR, a universal calcium mobilizer. MSC-mediated suppression of PHA-induced T-cell proliferation was restored to control levels in 3 of 4 patients post-BMT. CONCLUSION: The ability of MSC to downregulate T-cell priming, proliferation, and cytokine release is deficient in patients with SAA, persists indefinitely after immunosuppressive therapy, but seems to be restored after BMT. Whether these abnormalities are relevant to the pathogenesis of aplastic anemia remains to be determined.     

In aplastic anemia progenitor cells have a reduced sensitivity to the effects of growth factors.

We have recently shown that in patients with aplastic anemia (AA) recovering following immunosuppressive therapy, the persistent reduction in the bone marrow clonogenic potential is unrelated to suppressive effects of the myeloid stroma and intrinsic to the hematopoietic progenitors. We examined the mechanisms of this defect by determining the response of the aplastic CD34+ clonogenic precursors to proliferative signals induced by hematopoietic growth factors and comparing their results with those of a control population. Light density bone marrow mononuclear cells were lymphocyte and monocyte depleted and enhanced for the CD34+ progenitors by immunomagnetic selection. Selected progenitors were then cultured in the mixed colony assay with incremental concentrations of combinations containing erythropoietin (Epo), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3) and c-kit ligand. Bone marrow from aplastic patients had significantly fewer light density cells displaying the CD34 antigen (mean 0.65%, SD 0.35 vs. 1.62%, SD 1.4; p=0.002). Dose response studies on aplastic CD34+ cells demonstrated that at low concentrations of Epo, IL-3 and GM-CSF, clonogenic growth was significantly impaired but achieved normal values at concentrations giving plateau growth in control cultures. However, for all colony types, responses to effective concentrations of c-kit ligand corresponded with those of controls. These data suggest abnormalities at the receptor or signal transduction levels.     

再生障碍性贫血骨髓和外周血FL、SCF测定及临床意义

目的 :测定再生障碍性贫血 (AA)骨髓及外周血FL含量 ,并观察其与临床疗效的相关性。方法 :采用常规Elisa法测定AA骨髓和外周血Flt3 配体 (FL)含量 ,应用单色和双色免疫荧光标记流式细胞仪分析FL的分泌细胞。结果 :AA患者骨髓和外周血FL含量显著升高 ,约为正常的 2 5倍以上 ,外周血和骨髓浓度无区别 ;FL含量变化与疗效密切相关 ,治疗有效者 ,BM及PB中FL水平降低 ,与无效者相比区别显著 (P <0 .0 1)。治疗前后干细胞因子 (SCF)水平则无改变。正常人CD3 + 细胞内贮存有大量FL ,而CD3 + 细胞以膜型FL为主 ,胞内基本无FL存在。结论 :AA患者骨髓和外周血FL水平显著升高 ,主要由CD3 + 细胞产生 ,其含量与临床疗效密切相关。     

The role of Wilms' tumor gene peptide-specific cytotoxic T lymphocytes in immunologic selection of a paroxysmal nocturnal hemoglobinuria clone

OBJECTIVE: To clarify an expansion mechanism of a paroxysmal nocturnal hemoglobinuria (PNH) clone with the Wilms' tumor gene (WT1). MATERIALS AND METHODS: In PNH patients with the HLA-A*2402 allele, frequencies of peripheral blood (PB) WT1 peptide-specific and HLA-A*2402-restricted CD8+ cells and WT1 peptide-stimulated interferon-gamma-producing mononuclear cells (MNCs), cytotoxicity of WT1 peptide-specific and HLA-A*2402-restricted cytotoxic T lymphocyte (CTL) clone (TAK-1) cells on bone marrow (BM) MNCs, and after co-incubation with TAK-1 cells, changes in colony-forming unit granulocyte-macrophage colony formation of CD34+ cells and in CD59 expression in viable CD34+ cells were investigated. RESULTS: The frequencies of PB WT1 peptide-specific and HLA-A*2402-restricted CD8+ cells (p < 0.005) and WT1 peptide-stimulated interferon-gamma-producing MNCs (p < 0.02) were significantly higher in 5 PNH patients than 8 healthy volunteers (HV). In 5 PNH patients or 3 HV, TAK-1 cells significantly killed BMMNCs and suppressed colony formations of CD34+CD59+ and/or CD34+CD59- cells in the absence and presence of a WT1 peptide or only in the presence of the peptide, respectively, in an HLA-restricted manner. After co-incubation with TAK-1 cells, reduction rates of colony formation of CD34+CD59- cells were significantly less than those of CD34+CD59+ cells in 5 PNH patients (p < 0.002) and proportions of viable CD34+CD59- cells from 5 PNH patients significantly increased in the absence (p < 0.01) and presence (p < 0.01) of a WT1 peptide in an HLA-restricted manner. CONCLUSION: WT1 peptide-specific and HLA-restricted CTLs may play an important role in expansion of a PNH clone during immunologic selection and/or in the occurrence of BM failure via interferon-gamma in PNH.     

Aplastic anemia associated with systemic lupus erythematosus.

Hematologic complications of systemic lupus erythematosus (SLE) usually involve peripheral destruction of blood cells. We report a case of aplastic anemia associated with SLE observed during the remission phase of SLE 3 months after the beginning of treatment. CD8+ T cells in the patient's bone marrow may have suppressed maturation of hematopoietic progenitor cells, which may have induced the aplastic anemia associated with SLE. Repeated therapy with high-dose methylprednisolone resulted in lasting remission.     

Increased production of tumor necrosis factor-alpha by peripheral blood mononuclear cells in the patients with aplastic anemia

The activity of tumor necrosis factor-alpha (TNF-alpha) in the supernatant of cultured peripheral blood mononuclear cells (PBMC) was measured in patients with aplastic anemia. It was significantly higher in patients with aplastic anemia than in normal controls, both when PBMC were unstimulated or when they were stimulated with PHA. Results from aplastic anemia patients were also significantly higher than patients who had received allogeneic bone marrow transplants. In aplastic anemia patients, the TNF-alpha value produced by PBMC upon stimulation and the platelet count were inversely correlated, as well those patients who had high TNF-alpha values tended to have lower hemoglobin and leukocyte values although this was not significant statistically. These results suggest that the increased production of TNF-alpha by PBMC plays a role in the severe suppression of hematopoiesis in aplastic anemia.     

再生障碍性贫血患者CD8+细胞表面Fas的表达及其临床意义

目的探讨再障患者体内活化的T淋巴细胞数量的增多和功能的异常是否与其凋亡减少有关。方法应用流式细胞术检测特发性再障（n=36）、因苯中毒导致的继发性再障（n=16）、表现为全血细胞减少的骨髓增生异常综合征患者（n=8）和正常对照（n=9）的骨髓及外周血中CD8^＋细胞表面Fas的表达。结果再障患者CD8^＋细胞Fas的表达显著低于正常对照；治疗后病例中的有效组的表达显著高于特发性再障初治组、低于正常对照。骨髓单个核细胞（BMMNC）中CD8^＋细胞表面Fas的表达与外周血单个核细胞（PBMNC）中CD8^＋细胞表面Fas的表达成正相关，且均与外周血中性粒细胞水平成正比。结论再障患者体内异常活化的细胞毒性T淋巴细胞（CTL）通过Fas／FasL途径介导的自身凋亡减少，导致其数量增多，同时还存在功能亢进。     

CXCR4 chemokine receptors (CD184) and alpha4beta1 integrins mediate spontaneous migration of human CD34+ progenitors and acute myeloid leukaemia cells beneath marrow stromal cells (pseudoemperipolesis)

Marrow stromal cells play an important role in regulating the development and proliferation of haematopoietic stem cells (HSC) within the marrow microenvironment. However, the molecular mechanisms of stem cell-stromal cell interactions are not fully understood. We observed that mobilized peripheral blood and cord-blood-derived CD34+ progenitor cells, or CD34+ acute myeloid leukaemia (AML) cells spontaneously migrated beneath marrow stromal cells, an in vitro migration phenomenon termed pseudoemperipolesis. In contrast, the CD34+ myeloid leukaemia cell line, Kasumi-1, did not display pseudoemperipolesis. Cord blood CD34+ cells had a higher capacity than granulocyte-colony-stimulating-factor-mobilized CD34+ cells for pseudoemperipolesis (28.7 +/- 12%vs 18.1 +/- 6.1% of input cells within 24 h, mean +/- SD, n = 8), whereas 9.4 +/- 12.6% (mean +/- SD, n = 10) of input AML cells displayed this phenomenon. Pseudoemperipolesis of CD34+ progenitor and AML cells was significantly inhibited by pertussis toxin and antibodies to the CXCR4 chemokine receptor (CXCR4, CD184), but not control antibodies. Moreover, CD34+ and AML cell migration was significantly inhibited by a CS1 peptide that blocks alpha4beta1 integrin binding, but not by a control peptide, in which the fibronectin binding motif was scrambled. Pseudoemperipolesis was associated with an increased proliferation of migrated CD34+ progenitor cells but not AML cells within the stromal layer, demonstrated by cell cycle analysis and cell division tracking. We conclude that alpha4beta1 integrin binding and CXCR4 chemokine receptor activation are prerequisites for the migration of CD34+ haematopoietic progenitors and AML cells beneath marrow stromal cells. These observations suggest a central role of marrow stromal cells for HSC trafficking and homing within the marrow microenvironment.     

A trial of recombinant human interleukin-1 in patients with severe refractory aplastic anaemia

We report here the effects of in vivo administration of recombinant interleukin-1 alpha (rIL-1 alpha) to patients with severe, idiopathic aplastic anaemia. Four patients who were refractory to immunosuppressive therapy and were not bone marrow transplantation candidates received daily doses of 0.03 microgram/kg and 0.10 microgram/kg intravenously as 5 d courses. No significant changes in either peripheral blood counts or bone marrow cellularity were observed at either dose during or following therapy. Two patients showed increased numbers of bone marrow progenitor colonies. Lymphocyte phenotyping demonstrated an elevated percentage of CD8+/DR+ activated suppressor T lymphocytes prior to therapy. After rIL-1 alpha administration, the percentage of CD8+/DR+ cells was reduced or returned to normal in all patients. Significant side-effects included fever, rigours, fatigue, headache and nausea. Transient hypotension was observed at both doses in all patients. These results suggest that while rIL-1 alpha can be safely administered, no significant haematologic improvement was observed in patients with severe aplastic anaemia.     

Excessive production of tumor necrosis factor-alpha by bone marrow T lymphocytes is essential in causing bone marrow failure in patients with aplastic anemia

Aplastic anemia (AA) is regarded as an immunological disorder because of the clinical effect of immunosuppressive therapy. Recent studies have reported that cytokines play an important role in the development of AA. In the present study, we measured levels of T-cell derived intracellular cytokine production in peripheral blood and bone marrow (BM) of patients with AA. We demonstrated that BM lymphocytes, particularly CD4(+) and CD8(+) T cells, in patients with AA produced significantly higher amounts of tumor necrosis factor-alpha (TNF-alpha), compared with lymphocytes in normal controls. We have previously reported that expression of TNF receptor (R)1 and TNFR2 in the CD34(+) CD38(-) and CD34(+) CD38(+) fractions of patients with AA is significantly higher than those in normal control. These results indicate that BM stem cells in patients with AA may possess high sensitivity to TNF-alpha. This in turn suggests that TNF-alpha affects hematopoiesis at an earlier stage in AA patients than in normal controls. We strongly support the hypothesis that a simultaneous increase in TNF-alpha production by BM lymphocytes and sensitivity of stem cells to TNF-alpha leads to BM failure in AA.     

Ex vivo expansion of CD34<Superscript>+</Superscript> and T and NK cells from umbilical cord blood for leukemic BALB/C nude mouse transplantation

CBSCT with low incidence of GVHD is associated with higher rates of delayed engraftment and relapse compared with other stem cells transplants. The immune-mediated effect of NK and cytotoxic T cells against residual tumor cells was shown to prevent relapse and reinduce remission after bone marrow transplantation. We expanded CD34⁺ and T and NK cells ex vivo in cord blood with different cytokines combination and transplanted into leukemic BALB/C nude mouse. The results showed significant expansion of MNCs and CD34⁺ cells. The CD3⁺ T cells increased in the groups containing cytokines cocktail, especially in the group with IL-7 or IL-2. CD56⁺ NK cells number increased significantly only in a medium containing IL-2. Of the 20 engrafted BALB/C nude mice, 14 survived after 6 weeks transplantation, and the numbers in each group were from 3 to 4. Human CD3⁺ cells in the bone marrow of the survived mice were analyzed by flow cytometry and showed existing evidences. RT-PCR was used to detect leukemic fusion bcr/abl gene; all mice that experienced expanded cord blood transplantation could not be found to have expression of fusion bcr/abl gene. These suggest that T, NK cells as well as CD34+ cells could be expanded from CB MNCs in the same medium with the combination of cytokines. The expanded CB MNCs could reconstitute hematopoiesis and eliminate minimal residue leukemia disease in transplanted mice.     

Multiple myeloma: altered CD4/CD8 ratio in bone marrow

The expression of CD3, CD4 and CD8 antigens was simultaneously evaluated in peripheral blood and bone marrow lymphocytes from 22 multiple myeloma (MM) patients. The coexpression of CD11b and HLA-DR antigens was also analyzed within the CD4+ and CD8+ subpopulations in 4 MM patients. In peripheral blood the percentage of CD3+ and CD8+ cells was in the normal range, and the percentage of CD4+ was slightly reduced, leading to an altered CD4/CD8 ratio (less than 1) in only 7 patients. On the contrary, in bone marrow the percentage of CD4+ was profoundly reduced, leading to an altered CD4/CD8 ratio in all MM patients. As we previously reported in peripheral blood, an expansion of the CD11b+ and HLA-DR+ lymphocytes was observed within the CD4+ and CD8+ bone marrow T-cell subpopulations. A T-lymphocyte subset imbalance is more evident in bone marrow than in peripheral blood, and it is not due to a different lymphocyte distribution within the hematological compartments.