Incidence of traumatic spinal cord injury in Italy during 2013-2014: a population-based study.

STUDY DESIGN: Observational prospective population-based incidence study. OBJECTIVES: The main objective of this study was to assess the incidence of traumatic spinal cord injuries (TSCIs) and incidence rates, in order to provide estimates by age, gender, characteristics and cause. SETTING: This study was conducted at acute-care spinal cord injury (SCI) hospitals and SCI centers from 11 Italian regions, between 1 October 2013 and 30 September 2014. METHODS: Data of all consecutive patients with acute TSCI who met the inclusion criteria were obtained through case reporting by clinicians. The data were collected into a web database. Incidence rates and incidence rate ratios were calculated and stratified by age, gender, cause, level and completeness. RESULTS: From 50% of the entire population of Italy, 445 new cases of TSCI were included. The crude incidence rate of TSCI was 14.7 cases per million per year (95% CI: 13.4-16.4); the overall male to female ratio was 4:1 and the mean age was 54. Complete information was available in 85% of the sample and revealed tetraplegia in 58% and incomplete lesion in 67% of cases. The leading cause of TSCI was falls (40.9%) followed by road traffic accidents (33.5%). The leading cause was falls for patients over 55 and road traffic accidents for patients under 55. CONCLUSION: The changing trend of TSCI epidemiology concerns the increase in the average age of TSCI people and the increase of both cervical and incomplete lesions. The etiology shows the primacy of falls over road traffic accidents and suggests the need for a change in prevention policies.

Occurrence and predictors of employment after traumatic spinal cord injury: the GISEM Study.

STUDY DESIGN: Multicenter, prospective study. OBJECTIVES: To assess the occurrence and predictors of return to work after traumatic spinal cord injury (SCI). SETTING: Italian rehabilitation centers. METHODS: We evaluated patients previously included in the Italian Group for the Epidemiological Study of Spinal Cord Injuries study. A standardised telephone interview was used to collect data after a mean follow-up of 3.8 years. The main outcome measure was employment at the end of follow-up. RESULTS: A total of 403 patients, 336 men and 67 women, with a mean age of 41.8±16.3 years, were included in the follow-up. In all, 42.1% of patients were employed at the moment of the interview, though 62% reported a worsening in their employment level. Predictors of employment were education (P<0.0001), bowel continence (P=0.02), independence in mobility (P=0.0004), ability to drive (P<0.0001), participating in the community (P=0.0001) and ability to live alone (P<0.0001) while age (P<0.0001), being married (P<0.0001), tetraplegia (P=0.03), occurrence of recent medical problems (P=0.002), re-hospitalization (P=0.02), presence of architectonic barriers (P=0.009) and having a public welfare subsidy (P<0.0001), predicted unemployment. On the basis of multivariate analysis, younger age, education, absence of tetraplegia, ability to drive, ability to live alone, previous employment were independent predictors of employment after SCI. Employment at follow-up was related to several indicators of quality of life. CONCLUSION: Employment after SCI was rather frequent and was related to several patient characteristics and social factors. Specific interventions on the patient and on the social environment may favor employment after SCI and improve quality of life.

Sport, free time and hobbies in people with spinal cord injury.

STUDY DESIGN: Prospective, multicenter follow-up (F-U) observational study. OBJECTIVES: To investigate the changes in participation and sports practice of people after spinal cord injury (SCI) and their impact on perceived quality of life (QoL). METHODS: The questionnaire investigated the health status and management of clinical conditions and attendance of social integration, occupation, autonomy, car driving, sentimental relationships and perceived QoL in a SCI population 4 years after the first rehabilitation hospitalization. RESULTS: Respondents were 403, 83.4% male; 39% was tetraplegic. At F-U, 42.1% worked and studied, 42.2% still held their jobs or studies, and 69% drove the car. In all, 77.2% had bowel continence and 40.4% urinary continence. The results showed that for the 68.2% of respondents, the attendance of friends, relatives and colleagues during their free time was the same or increased compared with the time before the injury, whereas 31.8% showed a decrease. The amount of time the 52.1% of respondents left home was the same or increased compared with before the trauma, whereas 50.6% of the respondents said that the time they were engaged in hobbies was either the same or increased. CONCLUSION: SCI people who perceived their QoL as being higher, and whose attendance, autonomy and time was increased in respect to hobbies, were mainly men with an age range between 36 and 40 years, unmarried, paraplegic and with A-B Asia Score. Regarding the amount of time dedicated to practicing sports, the only difference was the most of that respondents, who indicated a decrease, were women.

[Occupational therapy and return to work of the people with traumatic spinal cord injury (TSCI)]. / Terapia Occupazionale e reinserimento lavorativo delle persone con esiti di mielolesione (TSCI).

The aim of this study was to evaluate the employment condition of persons with TSCI 4 years after discharge from rehabilitation facilities, as well as the factors related to better outcome. In the follow-up we interviewed 403 persons. We recorded the following variables: current employment status, causes of unemployment and their correlation with demographic status, clinical status and other information. In our results 51.4% of the interviewed persons were unemployed, 34.7% had a job and 7.2% were students. Among the unemployed persons 34% had suffered an accident at work, 31% had been unable to find suitable work and 31% were retired. Employment significantly correlated with younger age, single status, being paraplegic, being autonomous in bladder/bowel management, driving a car and a better quality of life. In the multivariate analysis the factors predicting better outcome were younger age, ability to drive and a better quality of life.

Pharmacological interventions for spasticity following spinal cord injury: results of a Cochrane systematic review.

UNLABELLED: The aim of this paper was to assess the effectiveness and safety of baclofen, dantrolene, tizanidine and any other drugs for the treatment of long-term spasticity in spinal cord injury (SCI) patients, as well as the effectiveness and safety of different routes of administration of baclofen. A systematic review of randomised controlled trials (RCTs), within the Cochrane Collaboration Injuries Group, was carried out. The Cochrane Injuries Group Specialised Register, the Cochrane Controlled Trials Register, MEDLINE, EMBASE and CINAHL were searched up to July 2006 without language restriction. Drug companies and experts active in the area were also contacted to find other relevant studies. Two investigators independently identified relevant studies, extracted data and assessed methodological quality of studies resolving disagreement by consensus. Nine out of 55 studies met the inclusion criteria. The heterogeneity among studies did not allow quantitative combination of RESULTS: Study designs were: 8 crossover, 1 parallel-group trial. Two studies (14 SCI patients) showed a significant effect of intrathecal baclofen in reducing spasticity (Ashworth score and activities of daily living [ADL] performances), compared to placebo, without any adverse effect. The study comparing tizanidine to placebo (118 SCI patients) showed a significant effect of tizanidine in improving Ashworth score but not in ADL performances. The tizanidine group reported significant rates of adverse effects (drowsiness, xerostomia). For the other drugs (gabapentine, clonidine, diazepam, amytal and oral baclofen) the results do not provide evidence for a clinical significant effectiveness. This systematic review indicates that there is insufficient evidence to assist clinicians in a rational approach to antispastic treatment for SCI. Further research is urgently needed to improve the scientific basis of patient care.

Follow-up in persons with traumatic spinal cord injury: questionnaire reliability.

UNLABELLED: AIM. The aim of this study is to show the compliance and the test-retest reliability of the questionnaire. METHODS: Construction of a structured questionnaire to perform a phone follow-up in 511 persons with traumatic spinal cord injury (SCI) 4 years after discharge from the first rehabilitative hospitalization. The questionnaire is structured in 24 items, comprising exclusion (closed questions) answers and 3 analogic scale answers, divided into 7 aspects: clinical conditions, sentimental relationships, quality of life, autonomy, mobility, occupation, social reintegration. A pilot survey on 20 subjects with SCI, hospitalized in different periods in 2 rehabilitation centers, was performed to check the questionnaire's feasibility and reproducibility. The persons were interviewed twice by telephone, with an interval of about one month, by a psychologist. The questionnaire was completed during one single phone conversation. RESULTS: No missing answers were recorded. The test run for this questionnaire showed high reproducibility based on the large numbers of questions with 100% correspondence between the answers ''before'' and ''after''. For most of the other questions this factor ranged between 80% and 99%, and for 2 questions on the analogic scale between 30% and 50%. CONCLUSIONS: The data collected by this pilot survey show the reliability of this questionnaire for all answers, save for the quantification of subjective variables.

Inhibition of human breast cancer cell (MCF-7) growth in vitro by the somatostatin analog SMS 201-995: effects on cell cycle parameters and apoptotic cell death.

Somatostatin (SS) and SS analogs have been shown to exert an antiproliferative effect on several transplantable tumors in animals and to reduce the growth of pancreatic, pituitary, and mammary tumor cells in vitro. We evaluated the effects that the SS analog SMS 201-995 exerts on growth, cell-cycle parameters, and suicidal cell death (apoptosis) of human breast cancer cells (MCF-7) in vitro. SMS 201-995 significantly reduced the MCF-7 cell growth induced by serum, estradiol, insulin, and insulin-like growth Factor-I in both short term and long term experiments. The effect was maximal when 10 nM estradiol was used as mitogen in long term cultures. SMS 201-995 treatment produced a slight but transient accumulation of cells in the G2/M phase but did not cause any noteworthy reduction in the percentage of proliferating cells. There was, instead, a time-related increase in the number of cells with the flow-cytometric characteristics of apoptosis in the cultures treated with the SS analog, which correlated well with its growth-inhibiting activity. It would, therefore, seem that SMS 201-995 exerts its inhibitory effect on MCF-7 cell growth in vitro mainly by enhancing the rate of programmed (or suicidal) cell death in the culture.

Growth-inhibitory effects of the natural phyto-oestrogen genistein in MCF-7 human breast cancer cells.

Genistein, a natural isoflavonoid phyto-oestrogen, inhibits the tyrosine kinase activity of growth factor receptors and oncogene products, as well as the in vitro growth of some tumour cell lines. The low incidence of breast cancer in countries with a flavonoid-rich soy-based diet and the protection afforded by soy-derived products against experimental mammary tumours in rats suggest that genistein and other isoflavonoid compounds may exert an anti-tumour activity. We analysed the effects of genistein on cell number and cell cycle progression (flow cytometric analysis of propidium iodide-stained nuclei) of human breast cancer cells (MCF-7) in vitro. Genistein produced a significant, dose-dependent inhibition of MCF-7 cell growth with an ID50 of approximately 40 microM after 72 h of incubation. Cell cycle analysis showed a reversible G2/M arrest in cell cycle progression at 10 microM genistein concentrations, whilst a marked fall in S-phase cell percentage associated with a persistent arrest in G2/M phase was observed in cultures treated with genistein doses equal to or greater than 50 microM. These effects were significant at 24 h of incubation; flow cytometric analysis at later times (48 and 72 h) revealed a population of cells with decreased DNA content and nuclear fragmentation characteristic of apoptosis. Thus, the growth inhibitory activity of genistein in MCF-7 cells results from the sum of cytostatic and apoptotic effects. Since the mitogenic action of insulin and insulin-like growth factor (IGF)-I in MCF-7 cells is a tyrosine kinase-dependent phenomenon, we analysed the genistein impact on S-phase entry produced by insulin in cultures partially synchronised in G0/G1 phase by serum deprivation. Insulin addition after a 36-h culture period in serum-free medium produced a strong increase in the percentage of S-phase cells (from 18.4 +/- 2.3 to 46.2 +/- 4.1 after 24 h) which was almost completely blocked by 100 microM genistein (20.1 +/- 3.1). Immunofluorescence analysis with a fluoresceine isothiocyanate (FITC)-conjugated anti-phosphotyrosine antibody revealed a strong increase in MCF-7 cell staining after insulin stimulation, but not when genistein was added with insulin. In conclusion, the dietary phyto-oestrogen genistein inhibits in vitro growth of MCF-7 human breast cancer cells through blocks in the "critical checkpoints" of cell cycle control and induction of apoptosis. These effects are likely to depend on impairment in the signal transduction pathway from tyrosine kinase receptor(s).

Genistein inhibits tumour cell growth in vitro but enhances mitochondrial reduction of tetrazolium salts: a further pitfall in the use of the MTT assay for evaluating cell growth and survival.

The natural isoflavone genistein inhibits the growth of a number of tumour cell lines in vitro. During investigations on the antiproliferative effects of genistein we observed that, with respect to direct cell counting, a tetrazolium (MTT) colorimetric assay consistently underestimated the growth inhibitory activity of the substance. Cell proliferation was markedly inhibited by genistein in three tumour cell lines (MCF-7, human breast tumour; Jurkat cells, human T-cell leukaemia; L-929, mouse transformed fibroblasts) when cell number was evaluated by direct counting, whereas a 72-h MTT assay failed to reveal any growth-inhibitory effect. Cell cycle analysis by propidium iodide staining and flow-cytometry revealed a G2/M cell cycle arrest after genistein treatment. Genistein-treated cells displayed an increase in cell volume and in mitochondrial number and/or activity, as revealed by enhanced formazan generation and increased uptake of the vital mitochondrial dye rhodamine 123. These results suggest that alterations in cell cycle phase redistribution of tumour cells by genistein may significantly influence mitochondrial number and/or function and, consequently, MTT reduction to formazan. This may constitute an important bias in analysing the effects of genistein, and possibly other drugs that block the G2/M transition, on growth and viability of cancer cells in vitro by MTT assay.

A rapid and simple method for measuring thymocyte apoptosis by propidium iodide staining and flow cytometry.

Corticosteroids, calcium ionophores and anti-CD3 monoclonal antibodies kill mouse thymocytes incubated in vitro. Cell death is preceded by extensive DNA fragmentation into oligonucleosomal subunits. This type of cell death (apoptosis), which physiologically occurs in the intrathymic process of immune cell selection, is usually evaluated by either electrophoretic or colorimetric methods which measure DNA fragmentation in the nuclear extracts. These techniques are unable to determine the percentage of apoptotic nuclei or recognize the apoptotic cells in a heterogeneous cell population. We have developed a flow cytometric method for measuring the percentage of apoptotic nuclei after propidium iodide staining in hypotonic buffer and have compared it with the classical colorimetric and electrophoretic techniques using dexamethasone (DEX)-treated mouse thymocytes. Apoptotic nuclei appeared as a broad hypodiploid DNA peak which was easily discriminable from the narrow peak of thymocytes with normal (diploid) DNA content in the red fluorescence channels. When the DEX-induced apoptosis was inhibited by either low-temperature (4 degrees C) incubation or cycloheximide treatment, no hypodiploid DNA peak appeared. Similarly, thymocyte death induced by sodium azide, a substance with cell-killing activity through non-apoptotic mechanisms, did not result in any variation in the normal DNA peak. The flow cytometric data showed an excellent correlation with the results obtained with both electrophoretic and colorimetric methods. This new rapid, simple and reproducible method should prove useful for assessing apoptosis of specific cell populations in heterogeneous tissues such as bone marrow, thymus and lymph nodes.

The natural tyrosine kinase inhibitor genistein produces cell cycle arrest and apoptosis in Jurkat T-leukemia cells.

Genistein, a natural isoflavonoid phytoestrogen, is a strong inhibitor of protein tyrosine kinases. We analyzed the effects of genistein on in vitro growth, cell-cycle progression and chromatin structure of Jurkat cells, a T-cell leukemia line with a constitutively increased tyrosine phosphorylation pattern. Exposure of in vitro cultured Jurkat cells to genistein resulted in a dose-dependent, growth inhibition. Cell-cycle analysis of genistein-treated cells revealed a G2/M arrest at low genistein concentrations (5-10 micrograms/ml), while at higher doses (20-30 micrograms/ml) there was also a perturbation in S-phase progression. The derangements in cell-cycle control were followed by apoptotic death of genistein-treated cells. Immunocytochemical analysis of cells stained with a FITC-conjugated anti-phosphotyrosine monoclonal antibody showed that 30 micrograms/ml genistein effectively inhibit tyrosine kinase activity in cultured Jurkat cells. Our results indicate that the natural isoflavone genistein antagonizes tumor cell growth through both cell-cycle arrest and induction of apoptosis and suggest that it could be a promising new agent in cancer therapy.

Protein tyrosine kinase inhibition and cell proliferation: is the [3H]-thymidine uptake assay representative of the T-lymphocyte proliferation rate?

T-cell growth is controlled to a large degree by extracellular signals that bind to specific receptors on the surface of cells. A number of these receptors have intrinsic protein tyrosine kinase (PTK) activity. Their action on second messenger generation, and thus on cell proliferation, has been indirectly demonstrated by the decrease in [3H]-thymidine (TdR) uptake that follows co-stimulation of T-cells with mitogens and PTK inhibitors such as genistein (GEN). In this paper we report that the [3H]-TdR uptake assay is not a valid and reliable tool for investigating the proliferative activity of certain T-cell lines. In fact, a concomitant assessment of both [3H]-TdR uptake and cell cycle progression demonstrated that GEN is able to block G2/M progression of Jurkat T-lymphocytes even at doses (5 micrograms/ml) that do not influence [3H]-TdR uptake. Pretreatment with sodium o-vanadate (100 nM) could not reverse the GEN-related cell cycle perturbation, but was able to restore optimal [3H]-TdR uptake. Finally, GEN treatment was able to induce concentration-dependent apoptotic cell death of Jurkat T-cells. The control of cell activation, proliferation and programmed cell death is undoubtedly influenced by receptor-associated PTKs. The final effect on cell survival is almost entirely dependent on the activation state of the cell. The [3H]-TdR uptake assay seems to be inadequate for a correct interpretation of the expected results.

A multicentre follow-up of clinical aspects of traumatic spinal cord injury.

STUDY DESIGN: Prospective, multicentred follow-up (FU) observational study. OBJECTIVES: Prospectively evaluate survival, complications, re-admissions and maintenance of clinical outcome in people experiencing traumatic spinal cord injury (SCI). SETTING: Seven spinal units and 17 rehabilitation centres participating in the previous GISEM (ie Italian Group for the Epidemiological Study of Spinal Cord Injuries) study. METHOD: A total of 511 persons with SCI, discharged between 1997 and 1999 after their first hospitalisation, were enrolled. A standardised questionnaire was administered via telephone. RESULTS: Of the 608 persons originally enrolled, 36 died between discharge and follow-up (mean 3.8+/-0.64 years). Of the remainder, 403 completed telephone interviews, 72 refused to participate and 97 could not be contacted. More than half of the patients interviewed (53.6%) experienced at least one SCI-related clinical problem in the 6 months preceding interview; the most frequent being urological complications (53.7%). At least one re-admission was recorded in 56.8% of patients between discharge and FU interview. Of the patients interviewed, 70.5% reported bowel autonomy and 86% bladder management autonomy. On multivariate analysis, lack of bowel/bladder autonomy was the most common variable with a strong predicting value for mortality, occurrence of complications and re-admissions. CONCLUSION: Re-admission and major complications seem common after SCI and should be considered when planning facilities. Failure to obtain bowel/bladder autonomy upon discharge from rehabilitation proved to be the most common predictive factor of poor outcome during the period between discharge and FU interview.

Dexamethasone and interleukins modulate apoptosis of murine thymocytes and peripheral T-lymphocytes.

Glucocorticoid hormones (GCH) induce apoptotic cell death in immature thymocytes through an active process, characterized by extensive DNA fragmentation into oligonucleosomal subunits. This requires macromolecular synthesis and is inhibited by interleukins (ILs). We performed experiments to analyse the possible effect of GCH on more differentiated lymphocytes, i.e. peripheral (from lymph nodes and spleen) T-lymphocytes. The results show that in vitro dexamethasone (DEX) induces DNA fragmentation and cell death not only in thymocytes but also in mature T cells. We also tested the possible role of interleukins (ILs) in the modulation of apoptotic cell death. We show that DEX-induced apoptosis is inhibited by IL-2 and IL-4 and that the IL-4 induced inhibition correlates with induction of c-jun (a component of AP-1 transcription factor). Furthermore high doses of IL-2 are able to induce apoptosis in both thymocytes and peripheral T cells. These data indicate that both thymocytes and peripheral T cells undergo apoptosis in response to appropriate stimuli and suggest that GCH and ILs interact in regulating T-lymphocytes apoptotic death.

Interleukin-4 protects double-negative and CD4 single-positive thymocytes from dexamethasone-induced apoptosis.

Glucocorticoid hormones (GCH) and anti-CD3 monoclonal antibodies (MoAbs) induce in mouse thymocytes and T-cell tumor lines an active process of cell death called apoptosis. Interleukins (IL), including IL-1 and IL-2, have been reported to inhibit such apoptosis. In this study we show that IL-4 also reduced the DNA fragmentation characteristic of dexamethasone (DEX)-induced apoptosis in thymocytes. This effect, studied in both time-course and dose-response experiments, was also detected at low IL-4 concentrations (1 U/mL) and against high DEX levels (10(-7) mol/L). The effect of IL-4 was blocked by an anti-IL-4 but not by an anti-IL-1 alpha MoAb, and was thus both specific and direct. Phenotypic analysis showed that IL-4 protects predominantly CD4-CD8- and CD4+CD8- cells. Our findings suggest that intrathymic T-cell development may be influenced by IL-4.

Cellular stress and glucocorticoid hormones protect L929 mouse fibroblasts from tumor necrosis factor alpha cytotoxicity.

Adaptive responses to the environment depend on the induction of the "stress response" in less differentiated organisms and cultured cells and the activation of the hypothalamic-pituitary-adrenal axis in animals and humans. This indicates that adrenal steroids and stress proteins play an important role in regulating cell survival in response to noxious stimuli. In an in vitro model, we analyzed the effects of either dexamethasone (DEX) treatment or environmental changes which can elicit a stress response, on the survival of cultured L-929 mouse fibroblasts exposed to the cytotoxic cytokine tumor necrosis factor alpha (TNF-alpha). DEX treatment produced a significant reduction in the apoptotic death of L-929 cells produced by TNF-alpha. Abrogation of the protective effect of DEX by actinomycin D and cycloheximide demonstrated that protection against TNF-alpha requires de novo synthesis of mRNA and proteins. The results were similar when L-929 cells were exposed to metabolic (serum starvation) or thermal (heat shock) stresses before TNF-alpha treatment. In both cases the stress process afforded significant protection against TNF-alpha cytotoxicity. Inhibition of mRNA and protein synthesis abrogated the protection exerted by stress (serum starvation) or produced massive death during the stress event (heat shock). The similarities in the protective activities of DEX and stress response and the reported interactions between heat shock proteins and glucocorticoid hormones suggest that stress proteins and glucocorticoids both belong to an ancient evolutionary pathway which controls cell survival.

Intestinal pseudoobstruction secondary to hypothyroidism. Importance of small bowel manometry.

Hypothyroidism may lead to secondary pseudoobstruction. We report a patient with intestinal symptoms from hypothyroidism in which previous conventional examinations were negative. Gastrointestinal manometry disclosed features of pseudoobstruction, and we discuss the importance of performing functional studies in selected cases, in as much as symptoms seemed to resolve on replacement therapy.

Cytostatic and cytotoxic effects of tumor necrosis factor alpha on MCF-7 human breast tumor cells are differently inhibited by glucocorticoid hormones.

To investigate the mechanisms of growth inhibition exerted by TNF-alpha on tumor cells in vitro, we analyzed the cytokine effects on growth and cell-cycle parameters of cultured MCF-7 human breast cancer cells. TNF-alpha exerted a dose-dependent inhibition of MCF-7 cell growth, which reached its maximum at 1000 U/ml TNF-alpha concentrations. Flow-cytometric analysis of cell nuclei revealed two main components in TNF-alpha activity: an earlier cytostatic effect (G1/S block), was followed by nuclear shrinkage and cytolysis. The 55-60-kDa TNF-alpha receptor is involved in the growth inhibitory activity of the cytokine, since the H398 anti-55-kDa receptor antibody significantly counteracted the cytostatic and cytotoxic effects of TNF-alpha while an antibody (htr-9) with agonistic activity on the same receptor produced both cytostasis and cytolysis. Culture conditions strongly influenced the MCF-7 cell response to TNF-alpha. Serum deprivation of log-growing (i.e., high S phase percentage) cultures potentiated the cytotoxic effect, while reduction in S phase cell percentage by preculture in serum-free medium resulted in a significant inhibition of TNF-alpha action. Mitogenic hormones, such as insulin and 17 beta-estradiol+insulin, restored the sensitivity of MCF-7 cells precultured in serum-free medium to both the cytostatic and cytolytic effects of TNF-alpha. The synthetic glucocorticoid hormone dexamethasone, at micromolar concentrations, counteracted the TNF-alpha effect on MCF-7 cell growth. Flow-cytometric analysis showed that dexamethasone did not antagonize the cytostatic activity of either TNF-alpha or htr-9 agonistic antibody, but only the subsequent cytolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-2 induces apoptosis in mouse thymocytes.

Interleukins play a role in the process of T-cell development and, like other cytokines, seem able to modulate apoptosis. Interleukin-2 has been reported to inhibit apoptotic cell death of thymocytes induced in vitro by either activation of CD3/TCR complex or treatment with glucocorticoid hormone. We demonstrate here that IL-2 can provoke DNA fragmentation and cell death of CD4+ CD8+ mouse thymocytes by activating an endogenous apoptotic pathway. Thymocytes, incubated with high IL-2 concentrations in vitro, showed the morphological characteristics of apoptotic cells, including reduction in nuclear size, derangement in chromatin structure, and DNA fragmentation in oligonucleosomal subunits. Inhibition of mRNA and protein synthesis and addition of the PKC-inhibitor H-7, Zn2+ ions, and IL-4 counteracted the IL-2 effect. These data suggest that high IL-2 concentrations may induce an active process of cell death on mouse thymocytes in vitro.

Glucocorticoid-induced DNA fragmentation: role of protein-kinase-C activity.

Glucocorticoid hormones (GCH) and IL-2 induce apoptotic cell death by a PKC-dependent mechanism. IL-4 counteracts apoptosis by inhibiting PKC activity. GCH and IL-2 show antagonistic effects on apoptosis when administered together. These data indicate that PKC activation in response to different stimuli can both enhance or reduce thymocyte survival.