CD95 (APO-1/Fas) expression on naive CD4(+) T cells increases with disease progression in HIV-infected children and adolescents: effect of highly active antiretroviral therapy (HAART)

We studied the expression of the CD95 receptor (APO-1/Fas) on peripheral blood T cell subpopulations in 37 HIV-1-infected children and adolescents stratified according to disease stage or antiretroviral treatment regimen and compared the results to values obtained in 12 healthy age-matched control subjects. CD95 expression on CD45RA(+) CD45RO(-)/CD62L(+) (resting/naive) and CD45RO(+) CD45RA(-) (primed/memory) CD4(+) and CD8(+) T cells was assessed quantitatively by four-color and three-color flow cytometry. CD4(+) T cells contained a population of predominantly CD95(-) resting/naive cells and a population of CD95(high) primed/memory cells, whereas CD8(+) T cells had a more uniform pattern of CD95 expression. The percentage of CD95(+) CD4(+) T cells increased with disease progression because of both an augmented median fluorescence intensity on resting/na?ve cells and an increased percentage of CD95(high) cells. Patients with highly active antiretroviral combination therapy who maintained stable CD4 counts in the presence of elevated plasma viral load had nearly normal numbers of CD95(-) resting/naive CD4(+) T cells, whereas CD95 expression in the CD8(+) T cell subset was still elevated compared with control subjects. Low CD95 expression on resting/naive CD4(+) T cells may therefore indicate a low risk for disease progression in antiretrovirally treated and untreated patients.     

静脉免疫球蛋白对新生儿脐带血淋巴细胞免疫抑制机制的研究

目的从脐带血单个核细胞(CBMC)和CD3^ T淋巴细胞膜表面CD25、CD45RA、CD45RO分子表达的角度,探讨静脉免疫球蛋白(IVIG)对新生儿免疫功能的抑制机制。方法利用IVIG和植物血凝素(PHA)不同组合对CBMC或CD3^ T淋巴细胞进行刺激培养,再利用四色免疫荧光抗体标记-流式细胞技术检测细胞表面CD25、CD45RA、CD45RO分子的表达情况。结果IVIG可以抑制PHA诱导的CBMC的活化,表现为CD25分子表达的明显抑制;并且随着CD25分子表达的抑制,CD4^ 细胞表面的CD45RO分子的表达也被抑制,阻止了CBMC中的CD4^ CD45RA^ 细胞向CD4^ CD45RO^ 细胞转换。IVIG也可以抑制PHA诱导的脐带血CD3^ T淋巴细胞CD25分子和CD45RO分子的表达,但这种抑制程度远远不如对CBMC作用明显。结论IVIG可以抑制脐带血T淋巴细胞的活化过程,这种抑制作用除了与IVIG对T淋巴细胞的直接作用外,还可能通过了其他免疫细胞或免疫分子的间接介导。IVIG对CD4^ CD45RO^ T淋巴细胞的抑制作用可能是IVIG抑制B淋巴细胞免疫球蛋白释放的重要机制之一。新生儿期应用IVIG有可能使免疫功能低下加重。     

肺炎支原体感染患儿T淋巴细胞亚群检测及分析

目的　观察肺炎支原体肺炎患儿急性期外周血T淋巴细胞亚群、T淋巴细胞活化状态的改变,探讨其发病机制。方法　采用流式细胞仪技术检测了2 0 0 2年1 0月至2 0 0 3年6月就诊于上海市金山区中心医院的1 7例肺炎支原体肺炎患儿急性期外周血T淋巴细胞亚群及T细胞亚群上CD2 5+的表达和CD4+细胞上CD4+CD45RA+、CD4+CD45RO+的表达;对照组为1 0例健康体检儿童。两组年龄、性别差异无显著意义。结果　肺炎支原体肺炎患儿急性期外周血CD3 +百分率( % )为( 62 . 2 3±6 .2 7) ,较对照组( 68 .60±4. 74)低,差异有显著性意义(P <0 . 0 5) ;CD4+、CD8+百分率较对照组差异无显著性意义(P >0. 0 5) ;CD8+CD2 5+百分率( % )为( 0 . 61±0 . 58) ,较对照组( 2 .1 6±0 . 40 )降低,差异有极显著性意义(P <0 .0 1 ) ;CD4+CD45RA+/CD4+CD45RO+比值与对照组相比降低(P <0 . 0 5)。结论　肺炎支原体肺炎时存在细胞免疫失调,主要表现为总T细胞降低,T细胞活化障碍和CD4+CD45RA+/CD4+CD45RO+平衡失调。     

Staphylococcus aureus skin colonization in atopic dermatitis children is associated with decreased IFN-gamma production by peripheral blood CD4+ and CD8+ T cells.

Atopic dermatitis (AD) is a chronic inflammatory skin disorder, which is associated with an increased expression of Th2 cytokines with concomitant decrease in IFN-gamma production by circulating CD4+ and CD8+ T cells. The skin of patients with AD is often colonized by Staphylococcus aureus, which may reflect in changes in immunological parameters. The aim of the study was flow cytometric measurement of some peripheral blood lymphocyte subsets expressing naive/memory marker (RA/RO) and activation marker (CD25) as well as intracellular production of IFN-gamma by peripheral blood CD4+ and CD8+ T cells from varied severity AD children and determine the impact of S. aureus skin colonization on cytokines profiles. There was a significant increase in the percentage of CD4+ and CD8+ T cells producing IL-4 and IL-13 and decrease in the percentage of CD4+ and CD8+ T cells producing IFN-gamma upon in vitro stimulation with phorbol 12-myristate 13-acetate and ionomycin in children with AD compared to healthy ones. The absolute number of CD4+ and CD8+ T cells expressing memory marker CD45RO was elevated as compared with controls. The severity of AD was positively correlated with the percentage of lymphocyte subsets: CD45RO+, CD4+CD45RO+, and the percentage of CD3+ and CD4+ expressing CD25 as well as the number of S. aureus on the skin. In conclusion, both CD4+ and CD8+ memory T cells are involved in the immunopathogenesis of AD. S. aureus skin colonization is related with disease severity and changes in expression of CD45RO and CD25 on T cells. A decrease in the percentage of CD4+ and CD8+ T cells producing IFN-gamma in AD children may explain propensity for skin infection.     

幼年类风湿关节炎患儿血清白介素-15变化与T_H细胞亚群表达的研究

目的：探讨幼年类风湿关节炎(JRA)患儿血清白介素15变化及其TH细胞亚群CD4+CD45RA+,CD4+CD45RO+的表达变化。方法：采用ELISA方法检测39例JRA患儿的血清IL15的水平,并同期选择26例年龄、性别无差异的健康儿童为对照。对其中24例JRA患儿采用免疫荧光标记技术和流式细胞仪检测外周血CD4+T淋巴细胞亚群CD4+CD45RA+,CD4+CD45RO+的表达。结果：JRA患儿组血清IL15水平显著高于正常对照组(P<0.05);JRA常见亚型中全身型患儿血清IL15水平明显升高,与对照组比较差异有显著性(P<0.01),而少关节型、多关节型患儿IL15水平与对照组比较差异无显著性(P>0.05);治疗后IL15水平较治疗前明显下降(P<0.01);JRA患儿血清IL15水平与外周血白细胞计数呈正相关(r=0.347,P<0.05),与血沉无相关(r=0.307,P>0.05),与C反应蛋白呈显著正相关(r=0.452,P<0.01);IL15高表达组患儿外周血CD4+CD45RO+T淋巴细胞数明显高于IL15低表达组患儿(P<0.05),CD4+CD45RA+T淋巴细胞数、CD4+CD45RA+T/CD4+CD45RO+T比值略低于IL15低表达组患儿,差异无显著性(P>0.05)。结论：JRA患儿血清IL15的水平显著升高;IL15升高使JRA患儿外周血CD4+T细胞表面CD45RA分子向CD45RO分子转换,促使T淋巴细胞大量激活,进而介导组织免疫病理损伤;在临床上可通过检测IL15以判断JRA的病情状况,为JRA治疗提供理论依据。     

幼年特发性关节炎患儿外周血Th细胞亚群变化

目的探讨幼年特发性关节炎(JIA)患儿外周血CD4 T淋巴细胞及其亚群CD4 CD45RA 、CD4 CD45RO 的表达及其临床意义。方法采用免疫荧光标记技术和流式细胞仪检测36例JIA患儿外周血CD4 T淋巴细胞及其亚群CD4 CD45RA 、CD4 CD45RO 的表达,同期检测20例年龄、性别无差异的健康儿童为对照。结果JIA患儿外周血CD4 T淋巴细胞明显低于对照组(t=2.099,P<0.05),CD4 CD45RA T淋巴细胞数与对照组比较明显降低(t=3.450,P<0.01),CD4 CD45RO T淋巴细胞数明显升高(t=3.913,P<0.01),CD4 CD45RA T/CD4 CD45RO T比值明显降低(t=4.904,P<0.01);与对照组比较,JIA各亚型(全身型、多关节型、少关节型)的CD4 CD45RO T淋巴细胞数均明显升高,CD4 CD45RA T/CD4 CD45RO T比值明显降低(P<0.01);CD4 CD45RA T淋巴细胞数与正常对照组比较在全身型中显著降低(t=4.192,P<0.01);在多关节型中明显降低(t=2.214,P<0.05);在少关节型中稍有降低,但与对照组比较差异无显著性(t=1.793,P>0.05)。结论JIA患儿的免疫功能紊乱主要表现为CD4 T淋巴细胞及其亚群CD4 CD45RA T/CD4 CD45RO T失衡,这可能在JIA发病机制中起着重要的作用。     

RSV感染患儿外周血CD_4~*”CD_(45)RO~+CD_(45)RA~+表达变化的研究

目的：探讨下呼吸道感染呼吸道合胞病毒(RSV)患儿外周血辅助性T淋巴细胞(CD4),原始T细胞(CD45RA+),记忆性T细胞(CD45RO+)表达的变化。方法：用单克隆抗体免疫荧光标记,流式细胞仪检测30例RSV下呼吸道感染患儿急性期外周血单个核细胞(PBMCs)CD4+,CD45RA+细胞,其中11例同时检测CD45RO+细胞,同期检测9例年龄、性别无差异的健康儿为对照。结果：RSV下呼吸道感染组患儿CD4为(32.74±10.60)%,明显低于对照组(40.76±6.82)%,2组有显著性差异(P0.05)。结论：RSV感染急性期存在免疫功能紊乱,外周血CD4,CD45RO+下降,而CD45RA+明显增加,这可能是CD45RO+向呼吸道迁移的结果。     

Passive smoking alters circulating naïve/memory lymphocyte T‐cell subpopulations in children

Vardavas CI, Plada M, Tzatzarakis M, Marcos A, Warnberg J, Gomez‐Martinez S, Breidenassel C, Gonzalez‐Gross M, Tsatsakis AM, Saris WH., Moreno LA, Kafatos AG. Passive smoking alters circulating naïve/memory lymphocyte T‐cell subpopulations in children.
Pediatr Allergy Immunol 2010: 21: 1171–1178.
© 2010 John Wiley & Sons A/S While it has been indicated that exposure to second‐hand smoke (SHS) can cause a local in vivo response, limited evidence exists on its possible systemic effects from population‐based levels of exposure. We investigated into a possible systemic response in the immune parameters and lymphocyte subsets, i.e. B cell (CD19+), T cell (CD4+CD45RO+, CD4+CD45RA+, CD3+CD45RO+, CD3+CD45RA+) and natural killer (CD3+CD16CD56+) lymphocyte subsets relative to exposure to SHS. Blood was drawn from healthy, verified non‐smoker, adolescent subjects (n = 68, mean age 14.2) and analysed for cotinine, antioxidants and lymphocyte immunophenotyping. SHS exposure was assessed using serum cotinine. Biomarker quantified exposure to SHS was correlated with a linear dose–response reduction in the percentages of memory CD4+CD45RO+ (p = 0.005) and CD3+CD45RO+ T‐cell subsets (p = 0.005 and p = 0.003, respectively) and a linear increase in the percentage of naïve CD4+CD45RA+ and CD3+CD45RA+ T‐cell subsets (p = 0.006 and p = 0.003, respectively). Additionally, higher exposure to SHS was associated with a higher CD4+CD45RA+ count (532 vs. 409 cells/ml, p = 0.017). Moreover, after controlling for age, gender, body mass index and plasma antioxidants, SHS exposure was found to be associated with the percentage of circulating naïve and memory CD4+ and CD3+ T‐cell subpopulations, as revealed through a linear regression analysis. These findings indicate a systemic immunological response in healthy adolescents exposed to population‐based levels of SHS exposure and imply an additional biological pathway for the interaction between exposure to SHS and its adverse effects on human health.     

Transient decrease in the CD45RA expression on T lymphocytes in neonates with fetal distress

To determine the expression of CD45 isoforms on T lymphocytes in neonates with fetal distress and to evaluate its diagnostic accuracy, peripheral blood samples were examined in 53 neonates who were classified into one of three groups: group I: 'control' group (n = 23), group II: 'mild distress' group (n = 15), and group III: 'moderate distress' group (n = 15). The expression of CD3 (mean +/- SD 24.2 +/- 10.1%), CD4 (23.0 +/- 5.7%), and CD45RA (27.3 +/- 9.6%) on total lymphocytes and the expression of CD45RA on CD4+ T lymphocytes (13.7 +/- 4.7%) in group III were significantly lower than in the other two groups 0-3 days after birth. Sensitivity and specificity of the CD45RA expression on CD4+ T lymphocytes for discrimination of group III were calculated as 0.79 and 1.0, respectively, when the cutoff value was 22.7%. The low CD3, CD4, and CD45RA expression returned to normal levels 10 days and more after birth. There were no differences in the CD8 and CD45RO expression between the groups. We conclude that CD4+ T lymphocytes from neonates with fetal distress show a transient decrease in the CD45RA expression without an increase in the CD45RO expression, and, therefore, analysis of the CD45 isoform expression is useful for laboratory evaluation of fetal distress.     

Analysis of changes in the percentage of B (CD19) and T (CD3) lymphocytes,subsets CD4, CD8 and their memory (CD45RO), and naive (CD45RA) T cells in children with immune and non-immune thyroid diseases

Graves' disease (GD) is an autoimmune thyroid disease caused by immunological abnormality. The immune cells (lymphocytes T and B) which infiltrate the thyroid gland play a key role in the development of autoimmune thyroid disease (AITD). The aim of this study was to evaluate the differences between distribution of T (CD3) lymphocytes, subsets CD4, CD8, and their memory (CD45RO), and naive (CD45RA) T cells and B (CD19) lymphocytes in the peripheral blood of patients with Graves' disease (GD) (n = 33, mean age 15.9 +/- 5.9 years) and non-toxic nodular goiter (NTNG) (n = 25, mean age 15.2 years), in comparison to age- and sexmatched healthy control subjects (n = 25, mean age 15.9 years). The percentages of peripheral blood lymphocyte subsets were analyzed by three-color flow cytometry using a Coulter EPICS XL cytometer. In the untreated Graves' patients we observed an increase in the percentage of CD19+ (p<0.007, p<0.003), CD4+ (p<0.004, p<0.017), CD4+CD45RO+ (p<0.04, NS), CD4/CD8 ratio (p<0.002, p<0.001) and a decrease in the percentage of CD8+ (p<0.02, p<0.02), CD4+CD45RA+ (p<0.04, p<0.03) cells in comparison to the healthy control subjects and euthyroid Graves' patients. These abnormalities were absent in children with non-toxic nodular goiter. In addition, the levels of CD3+, CD4+CD8+, CD8+CD45RO+ T cells and CD8 lymphocytes co-expressing CD45RA and CD45RO antigens were similar in all groups and no statistically significant differences were found in comparison to the healthy controls. In the untreated Graves' patients we found a positive correlation between serum levels of fT4 and fT3 and the percentage of CD19+ lymphocytes (r = 0.45, p<0.01, r = 0.37, p<0.04), between serum level of fT4 and the percentage of CD4CD45RO (r = 0.4, p<0.02) lymphocytes and between concentration of TRAb and CD4+ (r = 0.38, p <0.04) and CD19+ (r = 0.39, p<0.016) cells. Statistically significant negative correlations existed between TRAb, TPO-Ab or TG-Ab concentration in blood serum and the percentage of CD8+ lymphocytes (r = -0.55, p<0.002; r = -0.41, p<0.02; r = -0.51, p<0.004), and between fT4 concentration and the percentage of CD8+ (r = -0.39, p<0.02) lymphocytes. No such correlation was detected in patients with non-toxic nodular goiter. We conclude that the abnormal distribution of B lymphocytes, memory and naive T cell subsets in the peripheral blood in children and adolescents with untreated Graves' disease suggests their role in the development of autoimmunity. The normalization in the percentage of these immune cells after thyrostatic treatment in comparison to newly diagnosed patients confirms the immunomodulatory effect of methimazole therapy.     

sCD40L、CD4＋CD45RA＋T细胞及CD4＋CD45RO＋T细胞在儿童ITP中的作用

目的探讨协同刺激分子可溶性CD40配体（sCD40L）及CD4＋T辅助细胞CD45RA和CD45RO亚群在儿童特发性血小板减少性紫癜中的变化。方法用ELISA法检测25例ITP患儿血浆sCD40L水平;用微量全血流式细胞术法检测ITP患儿外周血CD4＋T辅助细胞CD45RA和CD45RO的表达率;并对sCD40L与血小板计数进行相关分析。结果ITP患儿血浆sCD40L浓度明显升高,与对照组比较差异有显著性（P〈0.05）;CITP组血浆sCD40L浓度升高更为明显,与AITP组或对照组比较差异均有显著性（P〈0.05）。ITP患儿CD4＋CD45RA＋T细胞表达率下降,CD4＋CD45RO＋T细胞表达率升高,差异均有显著性意义（P〈0.05）,而AITP和CITP之间差异无显著性（P〉0.05）。血浆sCD40L与外周血小板计数无相关性（r=-0.047,P〉0.05）。结论CD40L高表达导致的CD40L/CD40信号传导通路异常可能参与ITP发病;ITP患儿存在Th细胞亚群偏移,表现为Th1细胞减少,Th2细胞增多。     

Immunophenotype of blood lymphocytes in neuroblastoma-associated opsoclonus-myoclonus

OBJECTIVE: To determine whether the distribution of peripheral blood mononuclear cells (PBMCs) is altered in paraneoplastic opsoclonus-myoclonus (POM). METHODS: PBMCs from 17 children with POM, 17 children with OM but no tumor, and 17 controls were immunophenotyped using a comprehensive panel of surface markers by dual-laser flow cytometry. All groups were matched for age and gender; POM and OM patients were matched for treatment. RESULTS: In the POM patients, the CD4+ T-cell subset was smaller in both relative size (-18%, P = 0.02) and absolute size (-41%, P = 0.03) compared with controls. The CD4/CD8 ratio also was less (-29% to -44%) and was related to POM duration (P = 0.03). The absolute but not relative size of the gammadelta T-cell subset was reduced (-44%, P = 0.02). There were no significant abnormalities of CD19+ B-cells, CD3- or CD3+ NK cells, HLA-DR+ or CD25+ T-cells, or CD45RA+ or CD45RO+ T-cells. Prior tumor chemotherapy, which was associated with a higher percentage but not number of CD8+ T-cells, did not restore the CD4+ T-cell subset. When the POM and OM groups, which were not significantly different, were combined, chemotherapy decreased both the relative and absolute size of the CD19+ B-cell pool and had small effects on other lymphocyte subsets. CONCLUSIONS: POM is characterized by T-cell abnormalities of PBMCs, the most robust of which is reduction of the CD4+ T-cell subset and the CD4/CD8 ratio. Although this reduction was found previously in cerebrospinal fluid in POM patients, PBMC subsets did not otherwise reflect cerebrospinal fluid abnormalities. Longitudinal studies will be necessary to determine whether PBMC abnormalities could serve as treatment markers.     

sCD40L、CD4~+CD45RA~+T细胞及CD4~+CD45RO~+T细胞在儿童ITP中的作用

目的探讨协同刺激分子可溶性CD40配体(sCD40L)及CD4+T辅助细胞CD45RA和CD45RO亚群在儿童特发性血小板减少性紫癜中的变化。方法用ELISA法检测25例ITP患儿血浆sCD40L水平;用微量全血流式细胞术法检测ITP患儿外周血CD4+T辅助细胞CD45RA和CD45RO的表达率;并对sCD40L与血小板计数进行相关分析。结果ITP患儿血浆sCD40L浓度明显升高,与对照组比较差异有显著性(P<0.05);CITP组血浆sCD40L浓度升高更为明显,与AITP组或对照组比较差异均有显著性(P<0.05)。ITP患儿CD4+CD45RA+T细胞表达率下降,CD4+CD45RO+T细胞表达率升高,差异均有显著性意义(P<0.05),而AITP和CITP之间差异无显著性(P>0.05)。血浆sCD40L与外周血小板计数无相关性(r=-0.047,P>0.05)。结论CD40L高表达导致的CD40L/CD40信号传导通路异常可能参与ITP发病;ITP患儿存在Th细胞亚群偏移,表现为Th1细胞减少,Th2细胞增多。     

Interleukin-6 and Thrombocytopoiesis: Probable Role of Platelets During Acute Phase Responses

Recovery of cell-mediated immunity after cessation of chemotherapy for childhood acute lymphoblastic leukemia (ALL) was investigated in 14 children to monitor the duration of immune deficiency. The numbers of blood T cells and their subsets were analyzed at 0. 1, 3, 6, 9 and 12 months after discontinuation of therapy with monoclonal antibodies and flow cytometry. The total T-cell count was low at cessation but normalized at 1 to 3 months, whereas the T-cell subsets CD4 +, CD8+ CD4+ Leu8 -, and CD4 + CD45RA + recovered differently, In children ages 3 to 6 years, the numbers of CD4 + cells and their subsets were normal at cessation, whereas in children ages 7 to 18 years, CD4+ and CD4+Leu8+ cell counts normalized only at 6 months. The numbers of CD8 + cells or activated T cells were not increased and the CD4 + /CD8 + ratio was not inverted, unlike recovery after bone narrow transplantation. Although the groups showed a mean reversion to normal values by 6 months, there were individual patients who continued to have subnormal values for I year after therapy, some of whom exhibited increased susceptibility to infections.     

Recovery of Blood T-Cell Subsets After Chemotherapy for Childhood Acute Lymphoblastlc Leukemia

Recovery of cell-mediated immunity after cessation of chemotherapy for childhood acute lymphoblastic leukemia (ALL) was investigated in 14 children to monitor the duration of immune deficiency. The numbers of blood T cells and their subsets were analyzed at 0. 1, 3, 6, 9 and 12 months after discontinuation of therapy with monoclonal antibodies and flow cytometry. The total T-cell count was low at cessation but normalized at 1 to 3 months, whereas the T-cell subsets CD4 +, CD8+ CD4+ Leu8 -, and CD4 + CD45RA + recovered differently, In children ages 3 to 6 years, the numbers of CD4 + cells and their subsets were normal at cessation, whereas in children ages 7 to 18 years, CD4+ and CD4+Leu8+ cell counts normalized only at 6 months. The numbers of CD8 + cells or activated T cells were not increased and the CD4 + /CD8 + ratio was not inverted, unlike recovery after bone narrow transplantation. Although the groups showed a mean reversion to normal values by 6 months, there were individual patients who continued to have subnormal values for I year after therapy, some of whom exhibited increased susceptibility to infections.     

Immunologic monitoring of maintenance therapy for acute lymphoblastic leukaemia in children-preliminary report

BACKGROUND: In the study we evaluated immune reconstitution during maintenance therapy for acute lymphoblastic leukaemia (ALL) in relation to different treatment protocols and response of the immune system to the accompanying infections. PROCEDURE: The study group consisted of 40 children. The BFM protocol'90 was used in the standard risk group, while the New York protocol-in the high risk group. Assessment of the immune system was based on the analysis of peripheral blood mono-nuclear cells by flow cytometry and concentrations of immunoglobulins: G, M, A and IgE. Each patient was examined at 1-3 months' intervals. RESULTS: Following cessation of intensive therapy, the successive months of maintenance treatment showed: (1) a considerable depletion of B lymphocytes, a durable decrease in IgM, IgA and gradually increasing IgG; (2) a correlation between the time passing from the cessation of intensive therapy and increased numbers and percentage of B cells, and the helper/suppressor cell ratio. In the group of children treated according to the high risk protocol, compared to the low-risk group patients, we found lower levels of the following parameters: IgG, % lymphocytes: B and T lymphocytes (including CD4/CD8 ratio and "naive"/"memory" ratio) and NK cells (% and count). During infection: (1) a significant increase was noted in the percentage of T cells with HLA co-expression and monocytes with ICAM-1 co-expression, (2) the percentage of CD3(+)CD45RO(+) "memory" T cells was found to increase. CONCLUSIONS: Our findings indicate quantitative and qualitative changes of the immunity in children with ALL during maintenance therapy.     

Production of new T cells by thymus in children: effect of HIV infection and antiretroviral therapy

The decrease in the number of CD4(+) T cells during HIV infection is the result of both peripheral destruction of cells by the virus and inadequate replacement of these cells. Aging and HIV infection lead to lower production of new T cells by the thymus, and, therefore, a complete restoration of the immune system is not generally achieved in infected adults after antiretroviral therapy. Because children have a completely functional thymus, we addressed the effects of HIV-1 infection on the production of new T cells in vertically infected children and whether the decrease of viral load after therapy results in a restoration of thymic function. To analyze the thymic function, T-cell receptor rearrangement excision circles were measured by quantitative PCR. Our results indicate that HIV-infected children have lower T-cell receptor rearrangement excision circle levels than age-matched uninfected children, likely due to an inhibitory effect of HIV on thymic function. Additionally, in some patients, the decrease in viral load after retroviral therapy allows the generation of new T cells by the thymus, thus recovering the normal number of CD4 cells.     

Age-related changes in intracellular TH1/TH2 cytokine production, immunoproliferative T lymphocyte response and natural killer cell activity in newborns, children and adults

To evaluate the development of the neonatal immune system, we measured T lymphocyte response to Con A, intracellular IL-2, IL-4, IFN-gamma and IL-10 production, and natural killer cell (NKC) activity in 12 very preterm, 12 preterm and 20 term neonates, 10 children and 10 adults. Immunoproliferation to Con A was significantly lower in cord blood than in children or adults. The percentage of CD4+ lymphocytes was significantly higher in newborns while CD8+ cells were higher at older ages, with a resulting gradual decline of the CD4+/CD8+ ratio. The percentage of IL-2-producing CD4+ and CD8+ cells was higher in all newborn groups than in children and adults, while the percentage of IL-4-producing cells was higher for CD8+ and lower for CD4+ cells in cord blood than in children and adults. Neonates had substantially lower percentages of CD4+ and CD8+ IFN-gamma-producing cells. A significant negative correlation was observed between gestational age and IFN-gamma-CD4+-, IL-2-CD8+-, and IL-10- CD4+-producing cells. In addition, a positive correlation was found between gestational age and IL-10-CD8+-producing cells. Percentages of CD4+/CD45RA+ cells were higher and CD4+/CD45RO+ percentages were lower in newborns than in children and adults. NKC activity in infants was significantly correlated with gestational age and significantly impaired compared to children and adults. On the whole, these results suggest a gradual development of immunity during gestation and show significant immaturity of cellular immune response at birth. The reduction of NKC activity, the lower proliferative response of T cells, the reduced cytotoxic response and a dysregulated cytokine production may contribute to the neonatal increased risk of infection and to the low incidence of graft-versus-host disease after cord blood transplantation.     

Lymphocyte subsets in human tonsils: The effect of age and infection

The aim of the present study was to determine the effect of repeated tonsillitis on the development of lymphocyte subsets in the tonsils and among peripheral blood lymphocytes (PBL) of children. Subsets of T- and B cells were analyzed in the tonsils and in PBL of patients undergoing tonsillecto-my for idiopathic tonsillar hypertrophy, recurrent tonsillitis, or tonsillar hypertrophy and tonsillitis. The majority of the CD4+ cells in the tonsils displayed the CD45RO+ phenotype, while the majority of those in the PBL displayed the CD45RA+ phenotype. Likewise, the proportion of CD45RO+CD8+ cells was higher in the tonsils than among PBL. The proportion of CD4 cells expressing the CD45RO marker increased with age among PBL, but not in the tonsils. B cells, detected by their CD 19, CD20, and CD21 markers, were three times more abundant in the tonsils than in the PBL. The proportion of CD38+ cells showed a negative correlation with age, both in the tonsils and among PBL. Among PBL a striking age-related reduction was seen in the proportion of CD19+, CD21+ and CD38+CD21+ B cells. In contrast, in the tonsils age-related changes could be detected only in the proportion of CD21+CD38+ cells. No difference among patients with various clinical diagnoses was detectable in any of the T- and B cell subsets in the tonsils and PBL. Thus, lymphocyte subsets evolve independently in the tonsils and peripheral blood, with the repeated antigenic challenge of tonsillar lymphocytes not influencing circulating memory cells.