[Clinical characteristics of hospitalized children with respiratory syncytial virus infection and risk prediction of severe illness during the post-COVID-19 era in Kunming].

Objective: To compare the epidemiological and clinical characteristics of hospitalized children with respiratory syncytial virus (RSV) infection in Kunming among the pre-and post-COVID-19 era, and to establish a prediction model for severe RSV infection in children during the post-COVID-19 period. Methods: This was a retrospective study. Clinical and laboratory data were collected from 959 children hospitalized with RSV infection in the Department of Pulmonary and Critical Care Medicine at Kunming Children's Hospital during January to December 2019 and January to December 2023. Patients admitted in 2019 were defined as the pre-COVID-19 group, while those admitted in 2023 were classified as the post-COVID-19 group. Epidemiological and clinical characteristics were compared between the two groups. Subsequently, comparison of the clinical severity among the two groups was performed based on propensity score matching (PSM). Furthermore, the subjects in the post-COVID-19 group were divided into severe and non-severe groups based on clinical severity. Chi-square test and Mann-Whitney U test were used for pairwise comparison between groups, and multivariate Logistic regression was applied for the identification of independent risk factors and construction of the prediction model. The receiver operating characteristic (ROC) curve and calibration curve were employed to evaluate the predictive performance of this model. Results: Among the 959 children hospitalized with RSV infection, there were 555 males and 404 females, with an onset age of 15.4 (7.3, 28.5) months. Of which, there were 331 cases in the pre-COVID-19 group and 628 cases in the post-COVID-19 group. The peak period of RSV hospitalization in the post-COVID-19 group were from May to October 2023, and the monthly number of inpatients for each of these months were as follows: 72 cases (11.5%), 98 cases (15.6%), 128 cases (20.4%), 101 cases (16.1%), 65 cases (10.4%), and 61 cases (9.7%), respectively. After PSM for general data, 267 cases were matched in each group. The proportion of wheezing in the post-COVID-19 group was lower than that in the pre-COVID-19 group (109 cases (40.8%) vs. 161 cases (60.3%), χ2=20.26, P<0.001), while the incidences of fever, tachypnea, seizures, severe case, neutrophil-to-lymphocyte ratio (NLR), C-reactive protein and interleukin-6 levels were all higher than those in the pre-COVID-19 group (146 cases (54.7%) vs. 119 cases (44.6%), 117 cases (43.8%) vs. 89 cases (33.3%), 37 cases (13.9%) vs. 14 cases (5.2%), 69 cases (25.8%) vs. 45 cases (16.9%), 3.6 (1.9, 6.4) vs. 2.3 (1.8, 4.6), 9.9 (7.1, 15.2) vs. 7.8 (4.5, 13.9) mg/L, 20.5 (15.7, 30.4) vs. 17.2 (11.0, 26.9) ng/L, χ2=5.46, 6.36, 11.47, 6.42, Z=4.13, 3.06, 2.96, all P<0.05). There were 252 cases and 107 cases with co-infection in the post-and pre-COVID-19 groups, respectively. The proportion of triple and quadruple infection in the post-COVID-19 group was higher than that in the pre-COVID-19 group (59 cases (23.4%) vs. 13 cases (12.1%), 30 cases (11.9%) vs. 5 cases (4.7%), χ2=5.94, 4.46, both P<0.05). Among the 252 cases with co-infection in post-COVID-19 group, the most prevalent pathogens involving in co-infections, in order, were Mycoplasma pneumoniae 56 cases (22.2%), Influenza A virus 53 cases (21.0%), Rhinovirus 48 cases (19.0%), Parainfluenza virus 35 cases (13.9%), and Adenovirus 28 cases (11.1%).The result of multivariate Logistic regression showed that age (OR=0.70, 95%CI 0.62-0.78, P<0.001), underlying diseases (OR=10.03, 95%CI 4.10-24.55, P<0.001), premature birth (OR=6.78, 95%CI 3.53-13.04, P<0.001), NLR (OR=1.85, 95%CI 1.09-3.15, P=0.023), and co-infection (OR=1.28, 95%CI 1.18-1.38, P<0.001) were independently associated with the development of severe RSV infection in the post-COVID-19 group. The ROC curve of the prediction model integrating the above five factors indicated an area under the curve of 0.85 (95%CI 0.80-0.89, P<0.001), with an optimal cutoff of 0.21, a sensitivity of 0.83 and a specificity of 0.80. The calibration curve showed that the predicted probability in this model did not differ significantly from the actual probability (P=0.319). Conclusions: In the post-COVID-19 era in Kunming, the peak in pediatric hospitalizations for RSV infection was from May to October, with declined incidence of wheezing and increased incidence of fever, tachypnea, seizures, severe cases, and rates of triple and quadruple co-infections. Age, underlying diseases, premature birth, NLR, and co-infection were identified as independent risk factors for severe RSV infection in the post-COVID-19 period. In this study, a risk prediction model for severe pediatric RSV infection was established, which had a good predictive performance.

[Spatio-temporal distribution of pulmonary tuberculosis and influencing factors in Beijing, 2008-2018].

Objective: To understand the spatiotemporal distribution of pulmonary tuberculosis (TB) and influencing factors in Beijing from 2008 to 2018. Methods: The incidence data of pulmonary TB in Beijing from 2008 to 2018 were from Tuberculosis Information Management System of Chinese Disease Prevention and Control Information System. Software ArcGIS 10.2 was used to visualize the spatiotemporal distribution of pulmonary TB incidence. Getis's Gi* statistic was applied to analyze the spatial clustering of pulmonary TB incidence at street/township scale. Bayesian spatiotemporal model was applied to analyze factors affecting its spatiotemporal distribution, including urbanization rate, GDP per capita, number of hospital beds per thousand population, permanent migrant population and population density. Results: The reported pulmonary TB incidence showed a downward trend in the past 11 years in Beijing, from 58.64/100 000 to 30.43/100 000. The incidences were higher in Tongzhou, Changping and other newly developed urban districts, with the hot spots concentrated in local areas of these districts. The incidences of pulmonary TB were lower in Dongcheng, Xicheng and other old urban districts-with the cold spots also concentrated in these area. The risk for the incidence of pulmonary TB was associated with the urbanization rate and the permanent migrant population. For every 1% increase in the urbanization rate, the relative risk of pulmonary TB would increase by 1%. For every 10 000 person increase of permanent migrant population, the relative risk of pulmonary TB would increase by 0.6%. Conclusions: In Beijing, the current pulmonary TB prevention and control needs to be focused on the newly developed urban areas. Due to the accelerated process of urbanization, it is necessary to strengthen TB prevention and control in permanent migrant population to reduce the incidence of TB in Beijing.

[Epidemiological characteristics of adenovirus infection in hospitalized children with acute respiratory tract infection in Kunming during 2019].

Objective: To investigate the epidemiology and clinical characteristics of adenovirus (ADV)-caused acute respiratory tract infection among hospitalized children in Kunming, China. Methods: Clinical and laboratory data were collected from 467 children with adenovirus infection who were hospitalized from January 1, 2019 to December 31, 2019 in 6 grade A class Ⅲ hospitals in Kunming area. The basic characteristics, epidemiology, mixed infection and adenovirus genotypes of the patients were retrospectively analyzed. The patients diagnosed with adenovirus pneumonia (AP) were divided into two groups, severe AP (SAP) group and general AP(GAP) group according to the severity of illness. Mann-Whitney U test or χ2 test was used for comparison between groups, while multivariate regression was applied to analyze the risk factors of SAP. Results: Among 15 635 hospitalized children with respiratory tract infection, 467 cases were adenovirus positive, with a detection rate of 2.99%. Of the 467 patients with adenovirus infection, 284 were male and 183 female, the age was 2.4 (1.1,3.9) years, including 44 cases (9.4%) < 0.5 years, 59 cases (12.6%) of 0.5 to<1.0 years, 176 cases (37.7%) of 1.0 to <3.0 years, 150 cases (32.1%) of 3.0 to <7.0 years, and 38 cases (8.1%) of 7.0 to 14.0 years. Adenovirus infection was common in autumn and winter, and the high incidence months were October to December, which accounted for 51.6% (241/467) of the whole year cases. Co-infection was detected in 226 cases (48.4%) out of 467 patients, in which one pathogen co-infection was the most frequent form (172 cases, 76.1%). Of the 262 pathogen detected 108 (41.2%) were Mycoplasma pneumoniae. In 144 of ADV-positve cases (30.8%) were taken geno-typing was done by PCR amplification, the results showed that 74 cases (51.4%) were ADV 3, 7 subtypes and 65 cases (45.1%) of ADV 1, 2,6 subtypes. Of the 467 cases of ADV infection, 320 (68.5%) were diagnosed with pneumonia, 82 (17.6%) with upper respiratory tract infection and pharyngeal tonsillitis, and 65 (13.9%) with bronchitis, laryngeal bronchitis, and asthmatic bronchitis. Among the 320 patients with AP, 56 cases were severe and 264 cases were general. Two cases (3.6%) in severe group died. Compared with the GAP group, the age was young [17 (11,42) months vs. 24 (14,44) months, Z=2.222, P=0.026], the fever duration was long [8 (5,14) days vs. 6 (3,9) days, Z=3.380, P<0.01], and the proportions of preterm birth and having underlying diseases were high [respectively 19.6% (11/56) vs. 6.1% (16/264), 26.8% (15/56) vs. 10.2% (27/264), χ2=8.965,11.109, P<0.05] in SAP group. Referring to laboratory markers, white blood cell count, C-reactive protein, creatine kinase-MB and lactate dehydrogenase were significantly increased in SAP group as compared to GAP group(all P<0.05). Multivariate Logistic regression analysis showed that preterm birth (OR=3.284, 95%CI 1.079-9.993, P=0.036), underlying disease (OR=3.284, 95%CI 1.079-9.993, P=0.036), fever duration ≥10 d (OR=2.523,95%CI 1.195-5.328, P=0.015) and C-reactive protein ≥50 mg/L (OR=3.156, 95%CI 1.324-7.524, P=0.010) were positively correlated with the risk of SAP. Conclusions: The incidence of adenovirus infection among hospitalized children in Kunming was lower than the national level, and no outbreak occurred in 2019. Subtype 3 and 7 of ADV are the predominant strains for infection, which usually occurs in autumn and winter and mainly causes pneumonia. Premature birth, underlining diseases, long fever duration and markedly increased C-reactive protein are the risk factors for developing into severe pneumonia. This paper presents the prevalence and clinical characteristics of adenovirus infection in children at high altitude area.

[Effect of Bmi1 gene overexpression on hematopoietic differentiation colony-forming assay of human embryonic stem cells].

Objective: To study the effect of Bmi1 gene overexpression on hematopoietic differentiation colony-forming assay of human embryonic stem cells. Method: Human embryonic stem cell H1 was co-cultured with mouse bone marrow mesenchymal stem cells OP9 to simulate hematopoietic differentiation in vitro. On the eighth day of co-culture, CD34(+) hematopoietic progenitor cells were selected for colony- forming assay to induce hematopoietic colonies. The expression of Bmi1 gene and BMI1 protein in the process of H1 in vitro hematopoietic differentiation to CD34(+) precursor cells was respectively detected by real-time PCR and Western Blot. The human embryonic stem cell H1 which overexpress Bmi1 gene was subjected to hematopoietic differentiation in the same way. Compare the colonies generated by hematopoietic differentiation of the two types of H1 cells. Results: The expression of Bmi1 gene was first increased and then decreased in the process of in vitro hematopoietic differentiation to CD34(+) hematopoietic progenitor cells of human embryonic stem cells. Colony-forming assay showed H1 cells which overexpress Bmi1 gene produced significantly more erythroid colony forming units and mixed colony forming units than normal H1 cells. Conclusion: Overexpression of Bmi1 gene promote the production of erythroid and mixed colony forming units during hematopoietic differentiation of human embryonic stem cell H1.

Oridonin-induced apoptosis in leukemia K562 cells and its mechanism.

Oridonin, an extract from the Chinese herb Rabdosia rubescens, is currently one of the most important traditional Chinese herbal medicines. Recently oridonin has been reported to have anti- tumor effects in a large variety of malignant diseases. In this study, we investigated the apoptotic inducing effect of oridonin in leukemia K562 cells and its mechanism. Cell growth inhibition was measured using a microculture tetrazolium assay, apoptosis was measured by flow cytometry and electron microscopy as well as by DNA fragmentation analysis. Telomerase activity was measured by TRAP-enzyme- linked immunosorbent assay, and the expression of Bcl-2 and Bax proteins was detected by western blot analysis. The results showed that oridonin could inhibit the proliferation and induce apoptosis on leukemia K562 cells remarkably. Telomerase activity as well as Bcl-2 expression was down- regulated, while Bax expression was up-regulated concurrently, when apoptosis ocurred. We therefore conclude that oridonin demonstrated anti-proliferative and apoptosis-inducing effects on K562 cells in vitro, and that changes in bcl-2 and bax protein levels as well as telomerase activity may play an important role in its mechanism of action.

Expression of survivin and bax/bcl-2 in peroxisome proliferator activated receptor-gamma ligands induces apoptosis on human myeloid leukemia cells in vitro.

The present study was undertaken to investigate the mechanisms of peroxisome proliferator activated receptor-gamma (PPAR-gamma) ligand-induced apoptosis on human myeloid leukemia K562 and HL-60 cell lines. The results revealed that both 15-deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2) and troglitazone (TGZ) have significant anti-proliferation- and apoptosis-inducing effects on these two kinds of leukemia cells. Marked morphological changes of cell apoptosis including condensation of chromatin and nuclear fragmentation were observed clearly using Wright's and Hoechst 33258 staining. Reverse transcription-PCR and western blot analyses demonstrated that both survivin and bcl-2 expression were downregulated markedly, while bax expression was upregulated concurrently when apoptosis occurred. We therefore conclude that 15d-PGJ2 and TGZ have significant apoptosis effects on K562 and HL-60 cells in vitro, and that upregulation of bax as well as downregulation of survivin and bcl-2 expression may be the important apoptosis-inducing mechanisms. The results suggest that PPAR-gamma ligands may serve as potential therapeutic agents for both acute and chronic myeloid leukemia.

Anti-proliferative effects of oridonin on SPC-A-1 cells and its mechanism of action.

Oridonin, an extract from the Chinese herb Rabdosia rubescens, is currently one of the most important traditional Chinese herbal medicines. We investigated the anti-proliferative effect of oridonin on the lung cancer cell line SPC-A-1 and its mechanism of action. Growth inhibition was measured using a microculture tetrazolium assay and apoptosis was measured by several standard methods. Western blot analysis measured the expression of bcl-2 and bax proteins. Oridonin (> 28 micromol/l) inhibited the growth of SPC-A-1 cells and induced apoptosis. Marked morphological changes indicative of apoptosis were observed, especially in cells treated with oridonin for 48 - 60 h. Western blot analysis revealed downregulation of bcl-2 and upregulation of bax proteins following treatment with oridonin for 48 h. We conclude that oridonin demonstrated anti-proliferative and apoptosis-inducing effects on SPC-A-1 cells in vitro, and that changes in bcl-2 and bax protein levels may play an important role in its mechanism of action.

Tumor necrosis factor modulates CD 20 expression on cells from chronic lymphocytic leukemia: a new role for TNF alpha?

Tumor necrosis factor alpha (TNF alpha) is a pleiotropic cytokine that is constitutively produced by leukemic cells in B Chronic Lymphocytic Leukemia (B-CLL). It has been shown to have autocrine and paracrine functions in normal B cells and in B lymphoproliferative diseases. This study was conducted to determine the effect of TNF alpha (in vitro) on CD20 expression on cells from patients with B-CLL. Currently, anti-CD20 monoclonal antibody therapy is becoming a second line treatment in the management of B cell disorders like low-grade non-Hodgkin's lymphoma (NHL) and B-CLL. Our results demonstrate amply that very low doses of TNF alpha (0. 0125 ng/ml) can be used to significantly increase CD20 expression on cells from patients of B-CLL as evidenced by increases in both percentage positivity and mean fluorescence intensity. The upregulation is evident as early as 24 hours and is maintained for up to 72 hours. We propose that the upregulation is a direct result of in vitro differentiation stimulated by TNF alpha. The results presented can be exploited in the designing of priming protocols prior to antibody therapy and this is discussed.

SCF, IL-1beta, IL-1ra and GM-CSF in the bone marrow and serum of normal individuals and of AML and CML patients.

This study compared cytokine transcript and protein levels in BM cells of normal individuals and leukemic patients. AML differed from normal in that: (1) AML marrow cells contain more IL-1beta protein than normal cells, (2) IL-1ra transcripts are absent from AML marrow cells, (3) AML marrow serum contains less IL-1ra protein than normal, (4) peripheral blood and marrow serum of AML patireents contains more SCF protein than normal serum, and (5) SCF transcripts have been detected in AML marrow biopsies and not in aspirate cells. These data suggest that unbalanced cytokine production may make a significant contribution to the abnormal behaviour of AML cells.

Telomerase activity in preleukemia and acute myelogenous leukemia.

The development of acute leukemia from preleukemia involves the appearance of clones with increasing proliferative potential. The studies described here demonstrate that telomerase activity progressively increases as the bone marrow cells acquire increasing proliferative potential. This was demonstrated by measuring telomerase activity in normal bone marrow, in post-treatment lymphoma marrows with skewed Lyonization, and in MDS and AML marrows. The greater telomerase activity in myelodysplastic marrow than in normal marrow is not due to a higher proportion of blast cells or to a higher proliferative rate of the MDS marrow. These data demonstrate that the increasing proliferative potential of the marrow which occurs during the development of AML is associated with a simultaneous increase in telomerase activity.

Suppression of telomerase activity and cytokine messenger RNA levels in acute myelogenous leukemia cells in vivo in patients by amifostine and interleukin 4.

High levels of telomerase activity and high rates of cell proliferation are associated with a poor prognosis in acute myelogenous leukemia. Furthermore, cytokine production by leukemia cells is believed to play an important role in determining the proliferative characteristics of leukemia. The in vivo effects of two noncytotoxic agents on these parameters were determined in 33 acute myelogenous leukemia patients. Three daily doses of interleukin (IL) 4 or a single dose of amifostine reduced telomerase activity in the leukemia marrow cells in 7 of 9 and 11 of 13 patients, respectively. The administration of a single dose of amifostine resulted in a reduction in tumor necrosis factor alpha and IL-6 transcript levels in the marrow cells of 10 of 13 and 12 of 13 patients in which these transcripts were present. The administration of only three doses of IL-4 or a single dose of amifostine has a significant effect on leukemia cell parameters, which are believed to have a significant impact on the in vivo biology of the disease and on its response to remission induction therapy.

Patients with myelodysplastic syndromes benefit from palliative therapy with amifostine, pentoxifylline, and ciprofloxacin with or without dexamethasone.

Thirty-five patients with myelodysplastic syndrome (MDS) were registered on protocol MDS 96-02 and were receiving continuous therapy with pentoxifylline 800 mg 3 times a day and ciprofloxacin 500 mg twice a day by mouth; dexamethasone was added to the regimen for the partial responders and the nonresponders after 12 weeks at a dose of 4 mg by mouth every morning for 4 weeks. Amifostine was administered intravenously 3 times a week at 3 dose levels (200 mg/M(2), 300 mg/M(2), and 400 mg/M(2)) to cohorts of 10 patients each. Therapy has been continued for 1 year in responders. Twenty-nine have completed at least 12 weeks of therapy and are available for response evaluation. Of the 21 men and 8 women (median age, 67 years), 20 had refractory anemia (RA), 3 had RA with ringed sideroblasts (RARS), 5 had RA with excess blasts (RAEB), and 1 had chronic myelomonocytic leukemia (CMMoL). Five had secondary MDS. No differences were noted in response rates among the 3 dose levels. Seven patients did not respond at all, and 22 showed an improvement in cytopenias (76%). Three had a triple lineage response, 10 had a double lineage response, and 9 had a single lineage response (8 of 9 in absolute neutrophil count [ANC] and 1 had more than a 50% reduction in packed red blood cell transfusions). Fifteen patients responded only after the addition of dexamethasone, whereas 7 responded before. When examined by lineage, 19 of 22 showed improved ANC, 11 of 22 demonstrated more than 50% reduction in blood transfusions, improved Hb levels, or both, and 7 of 22 showed improvement in platelet counts. Interestingly, the responses were frequently slow to appear, and continued improvement in counts was seen up to 12 months of therapy and beyond. This study supports the feasibility of treating patients with MDS with the unique approach of cytoprotection and anticytokine therapies as well as the principle that prolonged commitment to treatment is desirable when noncytotoxic agents are administered. (Blood. 2000;95:1580-1587)

Biological characteristics of myelodysplastic syndrome patients who demonstrated high versus no intramedullary apoptosis.

Spontaneous intramedullary apoptosis was measured in bone marrow (BM) biopsies of 175 patients with myelodysplastic syndromes (MDS) using in situ end-labeling (ISEL) of fragmented DNA. Two groups of high (n=71) versus low (n =43) levels of apoptosis were identified while 61 patients were ISEL-negative. Semiquantitative assessment of 3 cytokines, the number of macrophages and in vivo labeling indices (LI) were also determined from consecutive sections of the biopsy. Patients with high apoptosis levels tended to have a high LI (p=0.013), more macrophages in their BM biopsies (p=0.006) and higher tumor necrosis factor alpha (TNF-alpha) levels (not significant) compared to patients with no apoptosis. In addition, low risk MDS patients had significantly lower rates of apoptosis (p = 0.047) and lower levels of TNF-alpha (p = 0.055) compared to high-risk MDS patients. We conclude that the genesis of cytopenias in MDS is of multifactorial origin and that cytokine-associated apoptosis clearly identifies a distinct biological subgroup of patients who may benefit selectively by use of anti-cytokine therapies.

Role of protein phosphorylation in EPO-mediated early signal transduction: analysis in the EPO-reactive cell line ELM-I-1 transfected with a c-fos-enhancer/promoter-luciferase reporter gene.

To investigate the role of protein phosphorylation in the early phase of EPO-mediated signal transduction, we EPO-stimulated a murine erythroid cell line ELM-I-1 transformed by plasmids comprised of the c-fos enhancer/promoter linked to the luciferase gene. Using this reporter gene system, we previously showed that EPO-induced activation of the c-fos promoter can be detected rapidly and sensitively as an elevation of cellular luciferase activity. In this study, we first examined the role of protein tyrosine phosphorylation. The tyrosine phosphatase inhibitor orthovanadate not only induced luciferase activity by itself but enhanced the action of EPO. On the other hand, the tyrosine kinase inhibitors erbstatin and herbimycin suppressed the effect of EPO. Next, the role of protein kinase C (PKC) in the EPO response was assessed. The PKC activator phorbol myristate acetate (PMA) not only induced luciferase activity by itself but enhanced the action of Epo. On the other hand, the PKC inhibitor 1-(5-isoquinolynyl-sulfonyl)-2-methylpiperazine (H7) suppressed the effect of Epo and PMA, whereas a nonspecific protein kinase inhibitor, N-(2-Guanidinoethyl)-5-Isoquinolinesulfornamine (HA1004) inhibited the action of neither Epo nor PMA. Another known PKC inhibitor staurosporine (STSP) did not inhibit but rather enhanced the effect of Epo. This action of STSP was blocked by H7 but not by HA1004. These results suggest that the EPO-mediated early signal transduction pathway leading to c-fos expression involves protein-tyrosine phosphorylation, is modulated by tyrosine phosphatase activity and is positively regulated by PKC.

A new system that analyzes erythropoietin-mediated early signal transduction: transfection of the c-fos enhancer.promoter-luciferase gene into a murine erythroid cell line.

Erythropoietin (Epo) exerts its effects by binding specific receptors on the surface of reactive cells. However, the signal transduction system after binding has not been well described. To develop a system to analyze the steps of signal transduction, we transfected the human c-fos-enhancer/promoter linked with the Photinus pyralis luciferase gene (pfosluc2) into a murine erythroleukemia cell line ELM-I-1, in which we previously showed that c-fos mRNA is rapidly induced upon Epo-stimulation. A stable transfectant was obtained. The cells transfected with pfosluc2 were stimulated with Epo and luciferase activity in the cells was measured as light intensity. The light intensity integrated for 2 min (LI2.0) was 3202 +/- 80 unit/1.5 x 10(5) cells before stimulation. This increased up to 5869 +/- 321 unit/1.5 x 10(5) cells by incubating the cells with 5 U/ml Epo for 2 h. After Epo stimulation, light intensity began to increase at 30 min, reached a peak (about 1.8 times the basal level) at 120 min, and then gradually dropped. The effect of Epo was dose-dependent; significant action occurred at as low as 0.5 U/ml, with a maximum at 5 U/ml. A similar response was observed when the cells were stimulated with interleukin-3 (IL-3) although the response was apparently lower than that with Epo. It was also found that IL-3 had an additive action with Epo on c-fos activity in this system. Thus, the above method was proven to be simple, rapid and sensitive enough to use to determine the early phase of signal transduction of Epo.

Interleukin-2 prevents programmed cell death in chronic lymphocytic leukemia cells.

When B-cell chronic lymphocytic leukemia (B-CLL) cells derived from peripheral blood are cultured in vitro, a substantial proportion die spontaneously by programmed cell death (PCD). In this study, we reexamined this phenomenon with both B-CLL and T-CLL cells, using a serum-free culture system. After 48 h of culture, in B-CLL cells, 23.3% +/- 6.7% (mean +/- S.E.M., n = 3) of total DNA was fragmented, while in 2 cases of T-CLL, this value was 32% and 45%, respectively. Analysis by electrophoresis indicated that the DNA of the B-CLL and T-CLL cells had been cleaved into regular oligonucleosome fragments comprising approximately 180-200 base pairs. This process was significantly promoted by methylprednisolone and the protein kinase A (PKA) activator Sp-cAMPS in at least some cases. Since B-CLL and T-CLL cells often possess interleukin-2 (IL-2) receptors on their cell membranes, we assessed the effects of IL-2 on spontaneous PCD. After a 48-h culture PCD was inhibited by 100 units/ml IL-2 by 31.7% +/- 6.6% in B-CLL (n = 3) and by 47% in one of 2 cases of T-CLL. This protective effect of IL-2 against spontaneous PCD was dose- and time-dependent. These findings suggest that the viability of B-CLL and T-CLL cells in vivo is regulated both positively and negatively by intrinsic IL-2, glucocorticoids, and regulators of PKA activity. This process of cell death may be involved in the development of CLL.

Interleukin-2 prevents programmed cell death in adult T-cell leukemia cells.

Adult T-cell leukemia (ATL) is a prototype of the lymphoma/leukemia syndromes involving immunologically mature T-lymphocytes. The first retrovirus described in humans, HTLV-1, is causally related to the disease. In this study, we examined whether ATL cells die in vitro through programmed cell death (PCD), which has been shown to occur in cells affected by several other acute and chronic leukemias. When ATL cells from peripheral blood were cultured in serum-free complete medium, a substantial proportion of them spontaneously died by PCD. After 48 h of culture, approximately 30% of the total DNA was fragmented. Electrophoresis indicated that the DNA of the ATL cells had been cleaved into regular oligonucleosome fragments each comprising approximately 180-200 base pairs. This process was significantly promoted by methylprednisolone and the protein kinase A (PKA) activator Sp-cAMPS in at least some cases. Since all ATL cells possess interleukin-2 receptors on the cell membrane, the effect of IL-2 on spontaneous PCD was assessed. PCD after 48 h of culture was inhibited by 30-50% by 100 U/ml interleukin-2 (IL-2). This effect of IL-2 to prevent spontaneous PCD was dose- and time-dependent. These findings suggest that the viability of ATL cells in vivo is regulated positively and negatively by intrinsic IL-2, glucocorticoid and regulators of PKA activity. Furthermore, the process of cell death may be involved in the development of the disease.