[Genetic and environmental factors of asthma and allergy: Results of the EGEA study]. / Facteurs génétiques et environnementaux de l'asthme et de l'allergie: synthèse des résultats de l'étude EGEA.

INTRODUCTION AND METHODS: The EGEA study (epidemiological study on the genetics and environment of asthma, bronchial hyperresponsiveness and atopy), which combines a case-control and a family-based study of asthma case (n=2120 subjects) with three surveys over 20 years, aims to identify environmental and genetic factors associated with asthma and asthma-related phenotypes. We summarize the results of the phenotypic characterization and the investigation of environmental and genetic factors of asthma and asthma-related phenotypes obtained since 2007 in the EGEA study (42 articles). RESULTS: Both epidemiological and genetic results confirm the heterogeneity of asthma. These results strengthen the role of the age of disease onset, the allergic status and the level of disease activity in the identification of the different phenotypes of asthma. The deleterious role of active smoking, exposure to air pollution, occupational asthmogenic agents and cleaning products on the prevalence and/or activity of asthma has been confirmed. Accounting for gene-environment interactions allowed the identification of new genetic factors underlying asthma and asthma-related traits and better understanding of their mode of action. CONCLUSION: The EGEA study is contributing to the advances in respiratory research at the international level. The new phenotypic, environmental and biological data available in EGEA study will help characterizing the long-term evolution of asthma and the factors associated to this evolution.

[The relevance of diagnostic criteria for latent tuberculosis before initiation of TNF-alpha inhibitors in psoriasis patients]. / Pertinence des critères diagnostiques de tuberculose latente avant traitement du psoriasis par anti-TNF-alpha.

BACKGROUND: Initiation of anti-TNF-alpha therapy requires prior screening for and treatment of tuberculosis. Diagnosis of relating to tuberculosis is based primarily on measurement of the papule induced by intradermal reaction to tuberculin (IDR). In this article, we discuss the validity of this criterion and the potential consequences of its use in relation to 15 patients. PATIENTS AND METHODS: This was a retrospective case study of patients presenting psoriasis and eligible for antibiotic therapy in whom latent tuberculosis was diagnosed and who received combined prophylactic antitubercular treatment for three months. All patients underwent thorough questioning and clinical examination, chest x-ray and QuantiFERON (QTF) testing, and all except one were tested for IDR. RESULTS: Thirteen patients were considered carriers of latent tuberculosis based on IDR greater than 5 mm, and on positive QTF for two others, one of whom had a documented history of primary tubercular infection. Six of these 15 patients (40%) developed hepatic cytolysis ascribable to their antitubercular treatment. DISCUSSION: Analysis of the respective characteristics of the IDR and QTF tests showed that only five of the 15 patients in our study were in fact presenting authentic latent tuberculosis, thereby suggesting that the diagnostic criteria for latent tuberculosis recommended by the French Medicines Agency (AFSSAPS), which are based solely on the size of the papule arising from IDR, are unsuitable for patients with psoriasis pending anti-TNF therapy. In our view, screening for latent tuberculosis in this patient population should involve both IDR for its sensitivity and QTF for its specificity, thereby avoiding overdiagnosis of tuberculosis leading to pointless exposure of patients to the risk of hepatic toxicity associated with antitubercular medication. CONCLUSION: We strongly recommend a change in the recommendations for prevention of tuberculosis by antibiotic therapy in patients with psoriasis, and that the review panels should include at least one dermatologist.

17q21 variants modify the association between early respiratory infections and asthma.

Single nucleotide polymorphisms (SNPs) at chromosome 17q21 confer an increased risk of early-onset asthma. The objective was to study whether 17q21 SNPs modify associations between early respiratory infections and asthma. Association analysis was conducted in 499 children (268 with asthma, median age 11 yrs) from the Epidemiological Study on the Genetics and Environment of Asthma (EGEA). The 12-yr follow-up data were used to assess persistent or remittent asthma in young adulthood. Respiratory infection before 2 yrs of age was assessed retrospectively. For the 12 17q21 SNPs studied, the odds ratios (OR) for association between infection and early-onset asthma (age at onset

[Environmental factors for asthma severity and allergy: results from the EGEA study]. / Facteurs environnementaux de l'asthme sévère et de l'allergie: résultats de l'étude EGEA.

INTRODUCTION: EGEA (Epidemiological study on the genetics and environment of asthma, bronchial hyperresponsiveness and atopy), a case control and family study including 2048 individuals, was initiated to look for environmental and genetic risk factors for asthma. A synthesis of the results obtained since 2002 on phenotypic and environmental aspects of asthma severity and allergy are presented in this article. METHODS AND RESULTS: The results support a role for hormonal factors in asthma severity and in various allergic markers of asthma. A greater body mass index was related to a more severe asthma in women with early menarche. Associations between markers of allergy (eosinophils, IgE and atopy) and hormonal dependent events in women (premenstrual asthma, menopause and oral contraceptive use) have been found. In asthmatics, exposure to agents known to be associated with occupational asthma, active and passive smoking were associated with an increased clinical asthma severity score. The study underlines the protective role of country living and exposure to pets in early life on allergy markers in adulthood, supporting the hygiene hypothesis. CONCLUSIONS: New hypothesis will be tested in the near future from the second stage of this survey.

[Sweet's syndrome associated with squamous cell bronchial carcinoma. Neutrophilic dermatosis and non-small cell lung cancer]. / Syndrome de Sweet révélant un carcinome bronchique épidermoïde. Cancer bronchique et dermatose neutrophilique.

INTRODUCTION: Sweet's syndrome, one of the neutrophilic dermatoses, is idiopathic in most cases. In 10-20% of cases it is paraneoplastic, associated with a solid tumour or haematological malignancy. An association with carcinoma of the bronchus has been only rarely described. CASE REPORT: We report the case of a 56 year old man who presented with Sweet's syndrome two months before the diagnosis of a squamous cell carcinoma of the bronchus. The dermatosis responded well to corticosteroids. The progress of the tumour was favourable, with stabilisation following 3 courses of chemotherapy and local radiotherapy. DISCUSSION: This case report updates this rare association and underlines the importance of undertaking appropriate thoracic investigations in the presence of this dermatosis. A paraneoplastic secretion of interleukin-8, GM-CSF and/or G-CSF by the bronchial tumour cells facilitating the recruitment of neutrophils, particularly in the skin, may account for the pathophysiology of this condition.

[Epidemiological study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy (EGEA) - First results of a multi-disciplinary study]. / Etude Epidémiologique sur les facteurs Génétiques et Environnementaux de l'Asthme, l'hyperréactivité bronchique et l'atopie (EGEA). Premiers résultats d'une étude multidisciplinaire.

The French co-operative epidemiological study EGEA realised in 1991/95 combines a case control study and a study of the families of asthmatic cases. A synthesis of the results already obtained is presented. Smoking was related to IgE, even in asthmatics and was clearly related to the clinical severity of asthma, an aspect insufficiently taken into account. The relationships of occupational exposures to asthma have been assessed using a job exposure matrix. Segregation analyses on IgE have shown, after correction for the mode of ascertainment, the existence of a dominant major gene and familial residual correlation. A systematic genome screen realised in families with 2 asthmatic siblings showed linkage of various regions in the genome implicated to asthma or related phenotypes (1p, 11p, 11q, 12q, 13q, 17q, 19q), coherent with genome screens realised in other studies. Regarding candidate genes, no association was evidenced between asthma and the AF508 mutation of the cystic fibrosis gene. The analysis is still in progress by studies on the heterogeneity of asthma with refined genetic studies and by searching to integrate results regarding environmental and genetic factors and studying their interactions.

[Neoadjuvant chemoradiotherapy and peroperative radiotherapy for non-small-cell lung cancer of the apex. A study of 5 cases]. / Chimio-radiothérapie néoadjuvante et radiothérapie per-opératoire dans les carcinomes non à petites cellules (CBNPC) de l'apex. Etude dur 5 cas.

The management of superior sulcus tumors with Pancoast 's syndrome is not well defined, especially in view of their low frequency. Even if surgery performed by "en bloc" resection of the tumor and the chest wall is recommended, neoadjuvant treatment could have a potential benefit on the resecability and pain control. We report five cases of Pancoast tumors (NSCLC), treated by radiotherapy and chemotherapy before surgery. Four tumors was on stage IIIb. A regimen with radiotherapy (50 Gy) and chemotherapy (cisplatinum + etoposide) was initially performed. Four tumors were resected, with 2 complete pathologic responses and good control on pain. Three patients received radiotherapy during surgery. No toxic reaction was observed. This regimen may be discussed with locally advanced tumors and poor prognosis.

[Epidemiological study of genetic and environmental factors in asthma, bronchial hyperresponsiveness and atopy. Protocol and potential selection bias]. / Etude épidémiologique des facteurs génétiques et environnementaux de l'asthme, l'hyperréactivité bronchique et l'atopie (EGEA). Protocole et biais de sélection potentiels.

BACKGROUND: The EGEA study combines a case-control study and a family study to assess genetic and environmental risk factors and their interactions for asthma, bronchial hyperresponsiveness and atopy. Information is scanty regarding potential selection biases, in particular regarding familial ressemblance in epidemiological surveys of this kind. METHODS: Asthmatic probands (adult and paediatric) were recruited in chest clinics of six clinical centres. Controls were mostly population-based (electoral rolls) for adults and recruited in surgery departments for children. RESULTS: The population examined includes 348 nuclear families ascertained by one asthmatic and 416 controls, totalling 1847 subjects (EGEA I) and an additional sample of 40 families ascertained by two asthmatic siblings (EGEA II). Potential biases for the various types of analyses have been studied. Quantification of the consequences of the greater participation of probands with a parental history of asthma shows it does not introduce a major bias in the estimates of familial resemblance. Cases and controls showed a good comparability regarding sex, age, area of residence and familial geographical origin, allowing proper associations studies for environmental and candidate genetic factors. CONCLUSIONS: The case-control component of the study will allow to perform studies on environmental factors and association studies for various genetic polymorphisms. Using the family base collected, segregation and genetic linkage/association analyses with DNA markers may be performed.

CD40 expression by human bronchial epithelial cells.

CD40 is a 50-kDa protein expressed on B cells, dendritic cells, monocytes and epithelial cells, but the distribution of CD40 expression in humans is not completely known. It binds to a ligand (CD40L) which is expressed essentially on activated T cells. The interaction between CD40 and CD40L plays important roles in immune responses. CD40 expression was investigated on bronchial tissues and human bronchial cell lines using immunohistochemistry, immunofluorescence staining and analysis with a cytometer, respectively. Constitutive CD40 expression, but not that of CD40L, was slightly detectable on normal human bronchial epithelial cells (HBEC) in situ and on an adult lung adenocarcinoma (SKLU1) cell line, while another cell line, a bronchial transformed SV40 cell line (WI26VA4), was negative for CD40. Among the various cytokines tested, only interferon (IFN)-gamma was found to induce CD40 expression on WI26VA4. Tumour necrosis factor (TNF)-alpha was the best cytokine able to up-regulate CD40 in SKLU1 cells. A combination of IFN-gamma and TNF-alpha was slightly more effective than the cytokine alone at up-regulating CD40 expression on both cell lines. We further investigated the functional consequences of CD40 ligation on both cell lines. These bronchial cells expressed CD40, HLADR and CD54 under basal conditions or when stimulated by cytokines. Stimulation through CD40 did not affect cell-surface-antigen expression on either cell line. The production of cytokines such as interleukin (IL)-6 and granulocyte macrophage-colony stimulating factor (GM-CSF) by HBEC has been described. SKLU1 and WI26VA4 cells released IL-6 and GM-CSF spontaneously. Whatever the case, CD40 engagement did not modulate spontaneous or TNF-alpha-induced production of these two cytokines. These data indicate for the first time that normal HBEC express CD40 in situ. Further investigations are required in order to determine the role of CD40 on normal HBEC.

RU 41740 (Biostim) stimulates the production of granulocyte macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro.

1. In this study, we observed the effects of RU 41740 (Biostim) on the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-8 (IL-8) in human bronchial epithelial cells in vitro. 2. Cytokine production was assessed by enzyme-linked immunosorbent assay. 3. We report that epithelial cells spontaneously released both cytokines and that RU 41740 induced a significant increase in production of IL-8 and GM-CSF. 4. This is the first observation of a stimulatory effect of an immunostimulating compound used in humans on cytokine production by epithelial cells.

Uptake of 12-HETE by human bronchial epithelial cells (HBEC): effects on HBEC cytokine production.

12-HETE, the major lipoxygenase end-product of platelets and macrophages, may be released in contact of bronchial epithelium in inflammatory diseases of the lung. We have studied the outcome of 12-HETE in presence of human bronchial epithelial cells (HBEC). When HBEC were incubated with [3H]12-HETE for 30 minutes, 27.5% of total radioactivity was found in HBEC and 72.5% in supernatants. Unesterified 12-HETE accounted for 22.4% of total radioactivity, 4.5% being recovered in phospholipids, preferentially in phosphatidylcholine and phosphatidylethanolamine. No incorporation in neutral lipids was detected. 72.9% of the incubated radioactivity was recovered in un identified metabolites. As 12-HETE has been shown to modulate the expression and production of various proteins, the consequence of the 12-HETE uptake on the release of GM-CSF and IL8 by HBEC was assessed. HBEC from control subjects were cultured for 24 hours with 12-HETE (10(-9) to 10(-7)M) in the presence or absence of TNF alpha. Detectable amounts of both cytokines were released in the supernatant in basal conditions at 24hr, and TNF alpha increased significantly the release of GM-CSF. 12-HETE at 10(-7)M weakly but significantly decreased the TNF-induced release of GM-CSF from HBEC. Thus the uptake of 12-HETE could affect the epithelial cell function in some situations.

Antihistamines and production of granulocyte-macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro: evaluation of the effects of loratadine and cetirizine.

1. In this study, we compared the effects of two antihistamine drugs on the production of granulocyte-macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro. 2. Cytokine production was assessed by the use of an enzyme-linked immunosorbent assay. 3. Epithelial cells spontaneously released both cytokines and tumor necrosis factor alone induced a significant increase in this production but loratadine and cetirizine had no effect at the various concentrations studied. 4. The antihistamines have no effect and this suggests that histamine plays no role in cytokine production under these conditions.

Increased respiratory burst and phosphodiesterase activity in alveolar eosinophils in chronic eosinophilic pneumonia.

A 43 year old woman presented with chronic eosinophilic pneumonia characterised by a high alveolar eosinophilic count, which allowed biochemical study of these cells. Alveolar eosinophils spontaneously produced high amounts of oxygen free radicals and exhibited an increased level of cyclic adenosine monophosphate (cAMP) phosphodiesterase (PDE) activity compared to blood eosinophils from control or allergic subjects. This activity was preferentially located in the plasma membrane, whilst the PDE activity of blood eosinophils from asthmatics or controls predominated in the cytosol. Because of the potential role of phosphodiesterase during eosinophil activation and recruitment, phosphodiesterase inhibitors may be useful in the treatment of eosinophilic pneumonia.

Leukotriene B4 production by blood neutrophils in allergic rhinitis--effects of cetirizine.

BACKGROUND: Mucosal inflammatory processes in late phase of allergic diseases involve cytokine production, cell adhesion molecule overexpression and release of inflammatory mediators with chemotactic activity, such as leukotriene B4 (LTB4). We had previously observed increased production of LTB4 by neutrophils in patients with allergic rhinitis and discussed the role of granulocyte macrophage-colony stimulating factor (GM-CSF) priming. Some antihistaminic compounds were shown to diminish the production of leukotrienes by neutrophils. OBJECTIVES: In a first step, we evaluated in ex vivo and in vitro studies, the effects of cetirizine on LTB4 production by blood neutrophils from allergic and healthy subjects. In a second step, we studied the in vitro effect of cetirizine on LTB4 production by neutrophils from healthy subjects during GM-CSF priming of these cells. METHODS: Neutrophils from both populations were purified from venous blood and LTB4 production was measured using high performance liquid cromatography (HPLC) method. RESULTS: In ex vivo studies, cetirizine treatment induced a decreased LTB4 production by neutrophils in allergic rhinitis. This effect of decreased LTB4 production was reproduced in vitro with 10(-8)-10(-6)M cetirizine. Nevertheless, this anti-H1 compound had no effect on neutrophil priming with GM-CSF. CONCLUSION: As LTB4 is an important chemotactic factor, Cetirizine could act on inflammatory cell recruitment by inhibiting LTB4 production by neutrophils.

Granulocyte-macrophage colony stimulating factors (GM-CSF) and interleukin 8 (IL-8) production by human bronchial epithelial cells (HBEC) in asthmatics and controls. Lack of in vitro effect of salbutamol compared to sodium nedocromil.

The bronchial epithelium produces cytokines that could contribute to inflammatory events in airways. In this study we determined the basal and TNFalpha stimulated productions of GM-CSF and IL-8 by human bronchial epithelial cells (HBEC) collected from 12 control and six asthmatic patients. Spontaneous and TNFalpha-induced GM-CSF or IL-8 released levels increased significantly with time. Epithelial cells from asthmatic patients spontaneously released high levels of GM-CSF (24 h). TNFalpha potentiated GM-CSF and IL-8 release in control subjects and only the IL-8 production in asthmatics. Nedocromil sodium, an antiinflammatory drug, and salbutamol, a beta2-agonist, are commonly used in asthma. They were evaluated on the spontaneous and TNF-induced expression of GM-CSF and IL-8 in cultured bronchial epithelial cells. Nedocromil sodium, at the concentration of 10(-6) M, reduced the TNF-induced increase in GM-CSF but not the IL-8 release. Salbutamol, at the concentration of 10(-6) or 10(-5) M, did not affect the constitutive or stimulated production of both cytokines.

Antibiotics and production of granulocyte-macrophage colony-stimulating factor by human bronchial epithelial cells in vitro. A comparison of cefodizime and ceftriaxone.

Cultured human bronchial epithelial cells (HBEC) produce both granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 8 (IL-8). The influence of cefodizime (CAS 69739-16-8), a new broad spectrum cephalosporin with immunostimulatory effects, and ceftriaxone on the production of GM-CSF and IL-8 in HBEC primary cultures was investigated. HBEC were isolated from biopsy specimens obtained during fibreoptic bronchoscopy in 12 patients (most frequent diagnosis: chronic bronchitis). Confluent monolayers of HBEC cultured on collagen were incubated for 24 h in a medium without study drugs (spontaneous production) or containing cefodizime or ceftriaxone at the clinically relevant concentrations of 1, 10 and 100 mg/l, with or without tumor necrosis factor alpha (TNF alpha, 100 U/ml). GM-CSF and IL-8 were measured in supernatant by ELISA technique. TNF alpha alone led to a significant (p < 0.005) increase in both GM-CSF and IL-8 production. Cefodizime induced a significant (p < 0.05), dose-dependent increase in GM-CSF release. No additive effect of cefodizime with TNF alpha was observed. Cefodizime did not affect IL-8 production and ceftriaxone had no influence on cytokine production. This is the first report of a stimulatory effect of a beta-lactam antibiotic on cytokine production by epithelial cells. GM-CSF production by epithelial cells is an important immunological step for neutrophil and monocyte recruitment and cell priming during lung defence. Previous studies with cefodizime in immunodepressed subjects have shown activation of phagocytosis and phagocytosis-related functions in non-lung phagocytes. An indirect mechanism of action, similar to that indicated by our results, may have been responsible for these stimulatory effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired G-proteins and cyclic nucleotide phosphodiesterase activity in T-lymphocytes from patients with sarcoidosis.

Among the various immune abnormalities which characterize active sarcoidosis, a low proliferative response of peripheral blood lymphocytes to mitogenic lectins has long been observed. Since membrane-associated G-proteins are very likely to be crucial elements in lectin signal transduction, we investigated the binding of 5'-guanylylimidodiphosphate (GppNHp), a non hydrolyzable GTP analogue, to blood total lymphocyte membranes and to blood T-lymphocyte membranes from patients with active sarcoidosis, and from healthy control subjects. GppNHp binding was markedly decreased in peripheral cells from patients with sarcoidosis as compared to controls, suggesting the occurrence of a defect at the level of G-protein(s). A further characterization of G-proteins in these cells by means of ADP-ribose-labelling in the presence of bacterial toxins brought forward a significant decrease in the labelling of a 40 kDa protein, the major pertussis toxin substrate, in membranes from sarcoid patients, while the labelling of the major 44 kDa cholera toxin substrate proved to be unchanged with respect to control membranes. It is hypothesized that, in sarcoid lymphocytes, a defect in the negative control of adenylate cyclase mediated by the inhibitory G-protein Gi, prevents the lowering of cAMP necessary to normal mitogenic response of blood lymphocytes to stimulation. cAMP degradation by the specialized enzyme phosphodiesterase constitutes another critical step in the control of cAMP levels. Both cAMP and cGMP phosphodiesterase activities were found decreased in blood total lymphocyte preparations from sarcoid patients. With purified T-cells, although the mean cAMP and cGMP phosphodiesterase activities from sarcoid patients were found more markedly decreased with respect to healthy donors, only the decrease in cGMP phosphodiesterase was found statistically significant. The role these defects in cyclic nucleotide degradation potentially play in the disturbance of blood lymphocytes response associated with sarcoidosis is discussed.

Pretreatment staging evaluation in small cell lung carcinoma. A new approach to medical decision making.

The real need for extensive staging at the time of diagnosis is discussed in regard to small cell lung carcinoma. We performed a decisional retrospective analysis on a series of 182 patients, based on three staging steps: the first step included physical examination and routine biologic tests. The second step consisted of liver ultrasonography and needle aspiration of any clinically detectable tumor mass, and the third step included bone marrow examination, radionuclide bone scan, thoracic, abdominal, and brain CT scan. A stepwise multivariate logistic regression performed on 11 variables considered in the first step shows that a four-parameter model can predict the spread of the disease (limited or extensive): weight loss, performance status, and elevated LDH or alkaline phosphatase levels. Limited disease can be predicted in two ways: (1) elevated LDH with normal alkaline phosphatases, no weight loss, and good performance status, or (2) normal LDH and alkaline phosphatases. In this series, 28 percent of patients can be predicted as having extensive disease and can be treated with chemotherapy alone without chest irradiation. After the second step, the probability of disease being extensive is only 25 percent, and only 84 (46.15 percent) patients would need to undergo the third step of staging procedures (brain CT scan, bone marrow aspiration and biopsy, radionuclide bone scan) with this method. We conclude that a multistep approach represents a simple staging method and offers the advantage of harmlessness and lower costs for patients not to be evaluated in prospective clinical trials.

[T-lymphocytes disorders in pulmonary sarcoidosis]. / Perturbations lymphocytaires T au cours de la sarcoïdose pulmonaire.

Sarcoidosis is a granulomatous disorder of unknown aetiology accompanied by variable immunological changes which concern both the monocyte and lymphocyte cell line. During the course of this disease anomalies of distribution (with accumulation in the disease tissue contrasting with a peripheral lymphopenia) and also of T cell functions (a predominance of CD4 T lymphocytes within the lesions and spontaneous expression of activation criteria) have been described. Recent works show some disturbances of T cell function and evoke the possibility of the initial pathology being related to this cell. Some current hypotheses place the T cell receptor for the antigen and the interleukin 2 receptor whose dysfunction will lead to an anomaly of the transduction of the activating signal of the T lymphocyte. The intrinsic origin (genetically determined) or extrinsically (retroviral) of these disturbances remains however to be determined.

Alteration of membrane phospholipid methylation by adenosine analogs does not affect T lymphocyte activation.

Membrane phospholipid methylation has been described during activation of various immune cells. Moreover recent data indicated modulation of immune cells functions by adenosine. As S-Adenosyl-methionine and S-Adenosyl-homocysteine are adenosine analogs and modulators of transmethylation reactions, the effects of SAH and SAM were investigated on membrane phospholipid methylation and lymphocyte activation. SAM (10(-5) M) was shown to induce the membrane phospholipid methylation as assessed by the 3H-methyl-incorporation in membrane extract. This effect was inhibited by SAH. In contrast SAM and SAH did not affect the phytohemagglutinin-induced proliferative response of peripheral blood mononuclear cells. SAH neither modified the early internalization of membrane CD3 antigens nor did it prevent the late expression of HLA-DR antigens on lymphocytes activated by phytohemagglutinin. These results indicate that in vitro alteration of phospholipid methylation does not affect subsequent steps of human T lymphocyte activation and proliferation.