Increase in Memory (CD4+CD29+ and CD4+CD45RO+) T and Naive (CD4+CD45RA+)T-Cell Subpopulations in Smokers

To examine the effects of smoking on lymphocyte subpopulations, we measured the following cell subpopulations: CD4+ T-cell subpopulations (i.e., CD4+CD29+, CD4+ CD45RO+, and CD4+CD45RA+ cells); CD8+ T-cell subpopulations (i.e., CD8+CD11a+ and CD8+CD11b+ cells); and natural killer cell subpopulations (i.e., CD16+CD57-, CD16+CD57+, and CD16-CD57+ cells). We measured these subpopulations, together with total CD4+ T, total CD8+T, total CD3+T, B (CD19+), and total lymphocytes, in 10 male heavy smokers, 38 male light-to-moderate smokers, and 33 male nonsmokers. The mean ages were 30 y, 31 y, and 32 y, respectively, and ages did not vary significantly among the smokers. CD4+CD29+ and CD4+CD45RO+ (memory T) cells in heavy smokers were significantly more numerous than those in light-to-moderate smokers and nonsmokers. Also, these memory T-cell subpopulations were significantly more numerous in light-to-moderate smokers than in non-smokers. The number of CD4+CD45RA+ (naive T) cells was significantly larger in heavy smokers than nonsmokers; numbers of CD4+CD45RO+ T and CD4+CD29+ T cells (memory T cells) were significantly correlated with daily cigarette consumption. Numbers of CD3+ T, CD4+ T, CD19+ B, and total lymphocytes in heavy smokers were significantly larger than in nonsmokers. There were significantly more CD3+ T, CD4+ T, and total lymphocytes in light-to-moderate smokers than in nonsmokers. The numbers of CD4+ T lymphocytes in heavy smokers were significantly larger than in light-to-moderate smokers. Perhaps CD4+ T cell subpopulations, especially memory T cells, are most susceptible to the effects of smoking on lymphocyte sub-populations.     

Association of low job control with a decrease in memory (CD4+ CD45RO+) T lymphocytes in Japanese middle-aged male workers in an electric power plant

To clarify the relationship between perceived job stress and lymphocyte subpopulations, a cross-sectional study was conducted in 231 male electric power plant workers (aged 40 to 60, mean 46 years). Job stress, i.e., job control, job demands, and social support at work, was assessed by means of the Japanese version of the Job Content Questionnaire. Blood samples were taken from all the workers, and numbers of CD4+ T lymphocyte subpopulations, total CD4+ T, T (CD3+) lymphocytes, CD16CD56+ natural killer (NK) cells, total lymphocytes, and white blood cells were determined. After controlling for age, number of cigarettes smoked per day, alcohol drinking, frequency of regular exercise, job demands, and social support at work by the partial correlation coefficients, numbers of memory (CD4+ CD45RO+) T, total CD4+ T, and total T (CD3+) lymphocytes were positively correlated with job control (p<0.05). Neither job demands nor social support at work showed significant correlations with lymphocyte subpopulations. It is suggested that lower job control is associated with a decrease in the number of CD4+ CD45RO+ T lymphocytes in male middle-aged workers.     

Decreases of natural killer cells and T-lymphocyte subpopulations and increases of B lymphocytes following a 5-day occupational exposure to mixed organic solvents.

The authors examined the effects of organic solvents on lymphocyte subpopulations in blood. Natural killer and T-lymphocyte subpopulations and B (CD19+) -lymphocytes were measured with flow cytometry in 16 male rotogravure printers on a Friday and on the following Monday. Numbers of all 3 subpopulations of natural killer cells (i.e., CD57+ CD16+, CD57- CD16+, and CD57+ CD16- cells), 2 subpopulations of T lymphocytes (CD4+ CD45RA+ and total CD8+ cells), and total lymphocytes on Friday were significantly fewer than those found on the following Monday. Conversely, the number of B lymphocytes on Friday was significantly larger than the number on Monday. The number of B lymphocytes was significantly correlated with blood toluene levels on Friday. The alteration in the number of CD57+ CD16+ NK cells from Friday to the following Monday was correlated inversely with the corresponding change in exposure level of toluene on Friday. The authors suggest that the effects of mixed organic solvents (primarily toluene) are recoverable decreases of natural killer cells and T lymphocytes and increases in B lymphocytes.     

Decreases of Natural Killer Cells and T-Lymphocyte Subpopulations and Increases of B Lymphocytes Following a 5-Day Occupational Exposure to Mixed Organic Solvents

The authors examined the effects of organic solvents on lymphocyte subpopulations in blood. Natural killer and T-lymphocyte subpopulations and B (CD19+) -lymphocytes were measured with flow cytometry in 16 male rotogravure printers on a Friday and on the following Monday. Numbers of all 3 subpopulations of natural killer cells (i.e., CD57+ CD16+, CD57-CD16+ and CD57+CD16- cells), 2 subpopulations of T lymphocytes (CD4+ CD45RA+ and total CD8+ cells) and total lymphocytes on Friday were significantly fewer than those found on the following Monday. Conversely, the number of B lymphocytes on Friday was significantly larger than the number on Monday. The number of B lymphocytes was significantly correlated with blood toluene levels on Friday. The alteration in the number of CD57+CD16+ NK cells from Friday to the following Monday was correlated inversely with the corresponding change in exposure level of toluene on Friday. The authors suggest that the effects of mixed organic solvents (primarily toluene) are recoverable decreases of natural killer cells and T lymphocytes and increases in B lymphocytes.     

低水平长期铅接触对作业工人淋巴细胞亚群的影响

[目的]检测淋巴细胞亚群以探讨低水平长期铅接触对免疫系统的影响。[方法]对44名铅作业工人和34名对照者采用流式细胞仪进行淋巴亚群分型及用酶联免疫法检测IgE,检测项目包括：CD3、CD4、CD8、CD45RO、CD19、HLADR、IgE。[结果]CD4^ CD45RO^ 、CD3^-HLADR^ 淋巴细胞铅接触组明显低于对照组,CD19^ 、CD4^ CD45RO^-、CD3^ HLADR^ 淋巴细胞和IgE两组间没有显著性差异。[结论]长期低水平铅接触可能影响T淋巴细胞亚群,从而影响细胞免疫功能。     

Decreases in CD8+ T, naive (CD4+CD45RA+) T, and B (CD19+) lymphocytes by exposure to manganese fume

To examine the effects of exposure to manganese (Mn) on the cellular and humoral immune system in men, T lymphocyte subpopulations, B (CD19+) lymphocytes, natural killer (NK) cells, and serum immunoglobulins (i.e., IgG, IgA and IgM) together with total T (CD3+) lymphocytes and total lymphocytes were measured in blood samples from 21 welders mainly exposed to Mn fume with blood Mn (BMn) concentrations of 0.6-2.3 (mean 1.4) microg/dl and 21 healthy controls working in the same factory (BMn concentrations: 0.7 to 1.7, mean 1.1 microg/dl). The workers engaged in welding for 6 to 36 (mean 17) yr. All the study subjects were divided into 3 equally sized groups (n=14 for each group) according to BMn concentrations. Numbers of CD8+ T, total T (CD3+), B (CD19+), and total lymphocytes were significantly lower in high-BMn group than those in low-BMn group; the numbers of CD8+ T lymphocytes were significantly lower in moderate-BMn group compared to low-BMn group. After adjusting for age and smoking, significant inverse correlations between BMn concentrations and CD4+CD45RA+ T, CD4+ T, CD8+ T, CD3+ T, and total lymphocytes were found. We conclude that T lymphocytes, especially CD8+ and CD4+CD45RA+ T lymphocytes, as well as CD19+ B lymphocytes are affected by exposure to Mn fume.     

慢性阻塞性肺疾病患者T淋巴细胞活化与凋亡的变化及临床意义

目的：探讨慢性阻塞性肺疾病（COPD）急性加重期和稳定期患者T淋巴细胞活化与凋亡的变化及临床意义。方法：将64例COPD患者分成2组：急性加重期组（34例）和稳定期组（30例），各组用荧光单抗CD3^ 、CD4^ 、CD25^ 、CD95^ 、CD3^ /CD25^ 、CD8^ /CD28^ 、CD8^ /CD28^-对淋巴细胞进行标记，用流式细胞仪计数。结果：与COPD稳定期相比，急性加重期患者体内CD3^ 、CD95^ 、CD3^ /CD25^ 、CD8^ /CD28^ T淋巴细胞减少，CD4^ 、CD25^ T淋巴细胞无明显变化，CD8^ /CD28^-T淋巴细胞增加。结论：COPD急性加重期患者T淋巴细胞总数减少，亚群发生变化，免疫调节功能紊乱，故在治疗疾病过程中，除对症处理处，必须配合使用调节细胞免疫药物，以改善免疫功能。     

Distribution of naïve (CD45RA+) and memory (CD45RO+) T-cells in HIV-infected Puerto Rican population

HIV infection usually results in a gradual deterioration of the immune system. It is evident that early recognition of progression markers during HIV infection from asymptomatic to symptomatic state is needed. In the present cross-sectional study, peripheral blood lymphocytes from 63 HIV-infected Puerto Rican individuals were analyzed by two-color flow cytometry to study the co-expression CD45RA and CD45RO on both CD4+ and CD8+ T-cells and its correlation with age, gender, CD4 count, CD4:CD8 ratio, anti-retroviral therapy, clinical status, and viral load. Measurement of T-cell subsets in these patients showed an excessive increase of CD3+CD8+, CD8+CD45RA+, and CD8+CD45RO+ T-cells as disease progresses. In contrast, it was also observed a significant decrease in CD3+CD4+, CD4+CD45RA+ and CD4+CD45RO+ T-cells. The distribution of CD8+CD45RA+ T-cells did not change significantly between HIV and AIDS cases suggesting that this T-cell subset is not a good progression marker. Interestingly, CD4+CD45RA+ T-cells were significantly difference between genders, and CD44+CD45RA+ and CD8+CD45RO+ T-cells were influenced by age. In conclusion, the distribution of na?ve/memory CD4+ T-cells and memory CD8+ T-cells significantly correlate with HIV infection in disease progression. It is also important to mention that these T-cell subpopulations may be influenced by both gender and age. Overall, these results suggest that a loss in the generation of new immune response and function may be occurring during disease progression. This study open new windows of understanding that will be beneficial for future studies on immunopathogenesis, diagnosis, prognosis, and treatment monitoring for HIV/AIDS.     

Decrease of suppressor-inducer (CD4+ CD45RA) T lymphocytes and increase of serum immunoglobulin G due to perceived job stress in Japanese nuclear electric power plant workers

To clarify the effects of perceived job stress on the immune system, a cross-sectional study was conducted in 116 male Japanese workers of a nuclear electric power plant (age, 20 to 39; mean, 31 years). Perceived job stress, i.e., psychological job demand, job control, worksite social support, and job strain, was assessed by means of the Japanese version of the Job Content Questionnaire. The job strain score was calculated as the ratio of the job demand score to the job control score. Blood samples were taken from all workers, and numbers of T and natural killer cell subpopulations, B lymphocytes, total lymphocytes and white blood cells, and serum concentrations of immunoglobulins (IgG, IgM, IgA, IgE and IgD) in their blood were measured. The workers were divided into higher and lower strain groups according to their job strain scores. The number of CD4+ CD45RA+ T lymphocytes in the higher strain group having the job strain score of 0.5 or more (41 workers) was significantly smaller than that in the lower strain group having the score of less than 0.5 (75 workers). In contrast, the serum IgG concentration in the former group was significantly higher than that in the latter group (analysis of covariance with age and smoking as covariates). Also, the numbers of total CD4+ T and total T (CD3+) lymphocytes and of white blood cells in the former group were significantly smaller than those in the latter group. After controlling for age and smoking by the partial correlation coefficient in all 116 workers, the number of CD57+ CD16+ natural killer cells was inversely correlated with job demand and with job strain; the number of CD8+ T lymphocytes was positively correlated with worksite social support; and serum IgG and IgM concentrations were positively correlated with job strain. It is suggested that higher job strain decreases the number of CD4+ CD45RA+ T lymphocytes in male Japanese workers but increases serum IgG concentrations.     

Immunophenotyping characteristic of the major lymphocyte populations and subpopulations in patients during salmonella infection

AIM: To study the quantitative changes in the major lymphocyte populations and subpopulations in the peripheral blood of patients during salmonellosis and find correlations of these changes with disease severity and bacterial clearance. MATERIAL AND METHODS: The study included 24 adult patients with culture-proven gastrointestinal salmonellosis. Flow-cytometry was used to identify CD19+ (B lymphocytes), CD2+ (total T lymphocytes), CD3(+)CD4+ (helper T cells), CD3(+)CD8+ (suppressor/cytotoxic T lymphocytes), CD4(+)CD29+ and CD4(+)CD45(-)RA+ (helper/ inducer subpopulation and naive Tlymphocytes) in the acute and the convalescent phases of disease. The absolute number and percentage of cells in 1 microl of peripheral blood were also determined. Immunophenotype analysis was conducted on an EPICS XL-MCL flow cytometer, Coulter, USA using monoclonal antibodies produced by the same firm. RESULTS: T and B lymphocytes and the immunocompetent T cells were slightly decreased transiently in the acute phase of the disease. Helper T lymphocytes were slightly increased with a significant increase observed of helper/inducer cells and decrease of the naive T lymphocytes. CONCLUSION: The increase of B lymphocytes at the height of salmonellosis bears additionally a diagnostic significance in determining the severity of the disease while the increase of the helper T lymphocytes can be a prognostic marker of early bacterial clearance.     

Flow cytometric analysis of lymphocyte subpopulations in the spleen and thymus of mice exposed to an acute immunosuppressive dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

The objective of the present studies was to determine if acute exposure to an immunotoxic dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produces alterations in the expression of lymphocyte surface markers as measured by multiparameter flow cytometry. The immunotoxicity of a single oral dose of TCDD was assessed by the anti-SRBC PFC response; an ED50 of 0.74 micrograms/kg was determined. Subpopulations in the spleen and thymus of C57B1/6 mice were analyzed 2 days following exposure to 2 micrograms/kg TCDD. In addition, splenic lymphocyte subsets were examined on Days 1-4 following SRBC challenge of mice treated with 0, 2, or 5 micrograms/kg TCDD. T and B cells were identified by single parameter analysis of Thy 1.2 and Ig expression. T cell subsets were defined by dual parameter analysis of CD4 and CD8 expression. In TCDD-treated mice, the percentage and the total number of double-positive CD4+ CD8+ thymocytes were significantly decreased while the percentage but not the total number of double-negative CD4- CD8- thymocytes was significantly increased. No changes in the percentage or total number of single positive (CD4+ CD8- or CD4- CD8+) thymocyte subsets were observed. In contrast to the thymus, lymphocyte subsets in the spleen were not significantly altered in percentage or total number 2 days following acute TCDD exposure. When splenic lymphocytes were analyzed daily following SRBC challenge, Ig+, Thy 1.2+, and CD4+ CD8- subpopulations remained relatively unchanged in both control and TCDD-treated animals. A small but significant decrease in the percentage of CD4- CD8+ T cells was observed on Day 3 in mice treated with 2 or 5 micrograms/kg TCDD when compared to that of vehicle-treated mice. The total number of CD4- CD8+ splenocytes was also significantly lower in the 5-micrograms/kg group on Day 3. However, this effect appeared to result from an elevation of the CD4- CD8+ subset in the controls rather than from a reduction in the TCDD-treated groups. Double-positive (CD4+ CD8+) lymphocytes were not detected in either control or TCDD-treated spleens. These results indicate that an acute dose of TCDD which reduced the splenic anti-SRBC response by 65-80% did not cause detectable changes in major splenic lymphocyte subpopulations. This is an important finding from the standpoint of utilizing lymphocyte subset analysis to screen for potential immunotoxic effects of TCDD. Specifically, the absence of subset changes does not preclude the presence of functional immunosuppression.     

儿童感染肺炎支原体后细胞免疫状态的变化及临床意义

目的:探讨儿童感染支原体肺炎后细胞免疫功能的变化及临床意义。方法:分别采用流式细胞术和细胞酶免疫分析法,对38例肺炎支原体感染患儿的T淋巴细胞亚群(CD3+、CD4+、CD8+CD28+、CD8+CD28-)的表达和红细胞补体受体1(CR1,即CD35)进行分子定量检测,45例普通肺炎患儿作为对照组检测上述指标。结果:支原体肺炎组患儿急性期红细胞CRl表达明显下降,CD3+、CD4+、CD8+CD28+表达减少,而CD8+CD28-表达升高,与对照组比较有显著性差异(P<0.01)。在恢复期上述情况有所改善,但与对照组相比仍有显著性差异(P<0.05),相关分析表明红细胞CR1与CD8+CD28-呈负相关(R=-0.512,P<0.05)。结论:支原体肺炎儿童存在红细胞免疫功能低下及T淋巴细胞活化异常,其中CD8+CD28-细胞群的活化障碍和红细胞免疫功能的持续异常,可能是发生继发性过敏性咳嗽的重要细胞免疫学基础。     

急性有机磷农药中毒并发多器官功能障碍综合征患者T淋巴细胞亚群的研究

目的 探讨急性有机磷农药中毒(AOPP)并发多器官功能障碍综合征(MODS)患者T淋巴细胞亚群的变化及其临床意义。方法 用荧光单抗CD3^ 、CD4^ 、CD8^ 、CD25^ 、CD28^ 对62名AOPP患者和30名健康人外周血淋巴细胞进行标记,在流式细胞仪下计数。结果 AOPP并发MODS患者体内CD3^ 、CD3^ /CD25^ 、CD8^ /CD28^ 明显减少(P＜0．01或P＜0.05);CD4^ 无明显变化(P＞0.05);CD95^ 、CD8^ /CD28^-明显增加(P＜0．01)。结论 AOPP并发MODS患者T淋巴细胞因大量凋亡而总数减少,亚群发生变化,造成免疫功能低下和紊乱,提示免疫失衡可能参与了AOPP后MODS的发病过程,因此在临床治疗过程中须重视改善患者免疫功能。     

接触苯女工淋巴细胞亚群及免疫状态调查研究

Peripheral blood from 29 female subjects occupationally exposed to benzene for an average duration of 8.6 years were analysed with monoclonal antibodies (McAbs). Acid alpha-naphthyl acetate esterase (ANAE)-positive cells among lymphocytes and serum IgG, IgA and IgM levels were determined simultaneously. The results showed a decreased total number of lymphocytes, reduction of percentages and absolute numbers of both CD2+ and CD4+ cells, decreased CD8+ and CD57+ cell numbers without significant changes in their percentages, a decreased CD4+/CD8+ ratio, an increased CD20+ cell percentage without significant change in its absolute number and a decreased serum IgM level. ANAE(+)-cell percentages of lymphocytes were of marked positive correlation to CD2+ cell percentages. These results indicate that benzene can cause immunosuppressive effects to the exposed subjects and the analysis of lymphocyte subpopulations by means of McAbs may be useful for evaluating early adverse health effects on workers exposed to the toxicant.     

肺结核患者细胞免疫功能与CD4＋T淋巴细胞凋亡相关性研究

目的 检测肺结核患者外周血CD4＋T淋巴细胞凋亡及免疫功能状态,探讨其与结核病发病的临床意义.方法 分离结核病患者和正常人外周血单个核细胞,标记后用流式细胞仪测定CD4＋T淋巴细胞凋亡率;用链霉亲和素碱磷酶法（SAP法）检测其外周血CD3＋T、CD4＋T、CD8＋T淋巴细胞及CD4/CD8比值;采用酵母菌花环法检测其红细胞受体花环率及红细胞免疫复合物花环率.结果 结核病患者外周血CD4＋T淋巴细胞凋亡率（15.882 ±4.65）％、CD8＋T淋巴细胞比例（27.69±0.74）％、红细胞免疫复合物阳性率（19.40±0.58）％显著高于对照组（P＜0.01）,CD3＋T淋巴细胞比例（46.48±1.34）％、CD4＋T淋巴细胞比例（28.12±0.69）％,CD4/CD8比值（1.0223±0.09362）和红细胞C3b受体阳性率（17.73±0.63）％明显降低（P＜0.01）;结核病患者CD4＋T淋巴细胞凋亡率与CD4＋T淋巴细胞比例之间以及T淋巴细胞亚群与红细胞免疫功能之间存在一定的相关性.结论 结核病患者CD4＋T淋巴细胞凋亡率显著增加致CD4＋T淋巴细胞数减少,T淋巴细胞免疫功能与红细胞免疫功能存在正相关,且均有所下降,可能与肺结核的免疫发病有关.     

Decreases of CD4- and CD8-positive T lymphocytes in retired chromate workers

To investigate the effects of chromates on the human immune system, we measured total T lymphocytes and their two major subpopulations (CD4 + and CD8 + T lymphocytes) in the peripheral blood of 19 retired male workers who had been exposed to chromate at a chemical plant. The results indicated that both CD4 + and CD8 + T lymphocytes were significantly decreased, resulting in decreases in total T lymphocytes and total lymphocytes.     

Repeated high-intensity Wingate cycle bouts influence markers of lymphocyte migration but not apoptosis

Studies have shown significant changes in lymphocytes during continuous exercise, but little has been shown on the effect of repeated high intensity bouts. This study was designed to examine the effect of repeated intermittent bouts on lymphocyte subset cell count, apoptosis, and migration. A series of 6 Wingate anaerobic cycle tests were performed by participants (N = 8) with blood samples attained before, immediately following, and after a designated recovery period (excess postexercise oxygen consumption (EPOC)) to observe lymphocyte changes. Lymphocyte subsets (CD4+, CD4/CD45RA+, CD8+, CD8+/CD45RA+, CD19+) were assessed for apoptosis (annexin V+) and cellular migration (CX(3)CR1). Our results indicate that the CD8+ and CD8+/CD45RA+ subsets were significantly influenced by the repetitive Wingate cycling protocol such that cell counts increased with exercise, and then decreased at EPOC termination (p = 0.016). The observed postexercise decrease in CD8+ and CD8+/CD45RA+ cells was accompanied by a significant change in the CX(3)CR1 cell migration receptor (p = 0.019), but not apoptosis (p = 0.87). This indicates that with repetitive high-intensity cycling, the response in CD8+ cells following the bout is likely due to cell migration rather than cell death.     

煤烟型大气污染对儿童免疫功能的影响

为了研究煤烟型大气污染对儿童免疫功能的影响 ,在煤烟型大气污染城市太原市的三个污染水平不同的研究区选取居住 3年以上 4 - 5年级的小学生测试T淋巴细胞亚群分类 (CD3+、CD4+、CD8+)、唾液溶菌酶含量和免疫球蛋白含量。结果发现小学生的唾液溶菌酶含量和免疫球蛋白 (IgG、IgA、IgM)均低于对照区 ,且有显著性差异 (P <0 .0 5) ;T淋巴细胞亚群分类 (CD3+、CD4+、CD8+百分含量 )有同样的趋势 ,但差异不显著 (P >0 0 5)。结果表明太原市煤烟型大气污染对小学生的非特异性免疫、体液免疫产生一定的影响 ,对细胞免疫影响不显著     

大鼠急性胰腺炎模型脾脏免疫状态的研究

目的 检测大鼠急性胰腺炎模型外周血及脾脏T淋巴细胞亚群，探讨急性胰腺炎病情发展过程中脾脏免疫功能状态的改变。方法 雄性SD大鼠随机分为对照组和实验组，胰管内逆行注射4％牛磺胆酸钠建立实验组胰腺炎模型，两组分别在3、6、12h分3批处死，每批12只。每只大鼠取胰腺组织观察病理改变，取股静脉血2ml及脾脏2g制成单细胞悬液，用流式细胞仪测定T淋巴细胞亚群CD3^ 、CD4^ 、CD8^ 及CD4^ ，／CD8^ 比值。结果 在胰腺组织炎性水肿阶段T淋巴细胞亚群无明显改变，在出血坏死阶段外周血CD3^ 、CD4^ 降低、CD8^ 轻度升高、CD4^ ／CD8^ 明显降低，脾脏细胞与外周血相比CD3^ 、CD4^ 及CD4^ ／CD8^ ，明显降低，脾脏呈现负性免疫状态，且随着炎症的加重变化更加明显。结论脾脏在重症急性胰腺炎中起负性免疫作用，加重SAP病情发展。     

Effects of L-arginine on the proliferation of T lymphocyte subpopulations

BACKGROUND: Dietary supplementation of L-arginine as a mechanism to enhance cellular immune response (T lymphocytes), has slowly gained approval, and appears especially important during critical illness. Despite its clinical use, little is known as to the direct effects of L-arginine on the different T lymphocyte subpopulations. METHODS: Lymphocytes were harvested from spleens of C57 B1/6 mice, and proliferation was induced with anti-CD3 in the presence of different concentrations of L-arginine ranging from 0 to 1000 micromol/L. Flow cytometry was used to evaluate the effect of L-arginine on T lymphocyte subpopulations. Interleukin-2 production was measured by ELISA and gene expression by RT-PCR. RESULTS: L-Arginine at or greater than 100 micromol/L significantly enhanced anti-CD3 stimulated T lymphocyte proliferation (p = .01). L-Arginine was essential for adequate T lymphocyte (CD3+) cellular maturation (p = .01). Proliferation of Helper T cells (CD4+) was not dependent on L-arginine. In contrast, Cytotoxic T cells (CD8+) showed a dose dependent proliferation in response to L-arginine (p = .01). Of the CD8+ cells, an increase in the CD45RA negative CD8 positive (memory) T cell subpopulation was observed with the addition of L-arginine. In addition, the number of cell surface CD8 receptors (CD8R) and CD3 receptors (CD3R) increased in the presence of L-arginine (p = .01, p = .04). Interleukin-2 receptor (IL-2R) expression was not up-regulated by L-arginine. L-Arginine modestly increased IL-2 production and had pronounced effects on its disappearance from the culture media (p < .0001). Interleukin-2 mRNA expression was not dependent on L-arginine. CONCLUSIONS: The requirements for L-arginine for the proliferation of CD3 stimulated T lymphocytes vary widely, and have to be taken into account when studying the mechanism of how L-arginine enhances cellular proliferation. L-Arginine may increase cellular proliferation by increasing specific receptor expression and the utilization of interleukin-2.