Association Between Seasonal Allergic Rhinitis and Air Pollution, Meteorological Factors, and Grass Pollen Counts in Madrid (1996 and 2009).

OBJECTIVE: The aim of this study was to assess the relationship between meteorological and pollution-related variables and the symptoms of patients with seasonal allergic rhinitis due to sensitization to grass pollen during 2 different time periods in Madrid, Spain. METHODS: Between March 23 and December 31 in 1996 and 2009, we carried out a daily count of grass pollen grains (Burkard spore trap) and recorded the rhinitis symptom scores in 2 groups of patients with a history of seasonal allergic rhinitis (n=25 in 1996 and n=23 in 2009). Descriptive statistics of the same variables during the study periods were recorded. Associations between variables were assessed using the paired-samples Wilcoxon test and categorical principal component analysis (CatPCA, SPSS24 package). RESULTS: The mean symptom score was low in 1996 and moderate in 2009. The 1996 and 2009 CatPCA analysis explained around 66.4% and 70.5% of the variance, respectively. The strongest relationships in 1996 were between symptoms and grass pollen counts (R=0.55) and between temperature and ozone (R=0.63). In 2009, the association between temperature and pollution-related variables was even stronger than in 1996 (ozone [R=0.53] and PM10 [R=0.34], with a positive sign in both cases). CONCLUSIONS: The effect of temperature and pollution (mainly ozone, even at lower atmospheric concentrations than in established guidelines for effects on health) may have contributed to the higher seasonal allergic rhinitis symptom score recorded in 2009.

Association between seasonal allergic rhinitis and air pollution, meteorological factors, and grass pollen counts in Madrid (1996 and 2009)

OBJECTIVE: The aim of this study was to assess the relationship between meteorological and pollution-related variables and the symptoms of patients with seasonal allergic rhinitis due to sensitization to grass pollen during 2 different time periods in Madrid, Spain. METHODS: Between March 23 and December 31 in 1996 and 2009, we carried out a daily count of grass pollen grains (Burkard spore trap) and recorded the rhinitis symptom scores in 2 groups of patients with a history of seasonal allergic rhinitis (n=25 in 1996 and n=23 in 2009). Descriptive statistics of the same variables during the study periods were recorded. Associations between variables were assessed using the paired-samples Wilcoxon test and categorical principal component analysis (CatPCA, SPSS24 package). RESULTS: The mean symptom score was low in 1996 and moderate in 2009. The 1996 and 2009 CatPCA analysis explained around 66.4% and 70.5% of the variance, respectively. The strongest relationships in 1996 were between symptoms and grass pollen counts (R=0.55) and between temperature and ozone (R=0.63). In 2009, the association between temperature and pollution-related variables was even stronger than in 1996 (ozone [R=0.53] and PM10 [R=0.34], with a positive sign in both cases). CONCLUSIONS: The effect of temperature and pollution (mainly ozone, even at lower atmospheric concentrations than in established guidelines for effects on health) may have contributed to the higher seasonal allergic rhinitis symptom score recorded in 2009

INTRODUCCIÓN: El objetivo de este estudio fue evaluar las relaciones de las variables meteorológicas y contaminantes en los síntomas de los pacientes con rinitis alérgica estacional con sensibilización al polen de gramíneas durante dos períodos diferentes en Madrid. MÉTODOS: Durante el período del 23 de marzo al 31 de diciembre de 1996 y 2009, se realizó un recuento diario de granos de polen de gramíneas (Burkard spore trap) y puntuación de síntomas de rinitis en dos grupos de pacientes (n = 25 en 1996 y n = 23 en 2009) con historia de rinitis alérgica estacional. Para describir cómo se relacionan las variables, se realizaron estadísticas descriptivas de las mismas variables en los períodos de estudio de 1996 y 2009, contraste no paramétrico pareado de Wilcoxon y un análisis de componentes principales (CatPCA, SPSS24). RESULTADOS: El valor medio de la puntuación de síntomas en 1996 fue bajo y en 2009 moderado. El análisis CatPCA de 1996 y 2009 explica aproximadamente el 66,4% y el 70,5% de la varianza, respectivamente. La relación más fuerte en 1996 fue entre los síntomas y los recuentos de polen de gramíneas (R = 0,55), la temperatura y el O3 (R = 0,63). En 2009, la relación entre la temperatura y las variables de contaminación fue incluso mayor que en el período de 1996: O3 (R = 0,53) y con PM10 (R = 0,34), en ambos casos con un signo positivo. CONCLUSIONES: El efecto de la temperatura y la contaminación (principalmente O3, incluso a concentraciones atmosféricas más bajas que las pautas establecidas sobre sus efectos en la salud), podría contribuir a la mayor puntuación de síntomas de rinitis alérgica estacional observada en 2009

Oral myeloid cells uptake allergoids coupled to mannan driving Th1/Treg responses upon sublingual delivery in mice.

BACKGROUND: Polymerized allergoids coupled to nonoxidized mannan (PM-allergoids) may represent novel vaccines targeting dendritic cells (DCs). PM-allergoids are better captured by DCs than native allergens and favor Th1/Treg cell responses upon subcutaneous injection. Herein we have studied in mice the in vivo immunogenicity of PM-allergoids administered sublingually in comparison with native allergens. METHODS: Three immunization protocols (4-8 weeks long) were used in Balb/c mice. Serum antibody levels were tested by ELISA. Cell responses (proliferation, cytokines, and Tregs) were assayed by flow cytometry in spleen and lymph nodes (LNs). Allergen uptake was measured by flow cytometry in myeloid sublingual cells. RESULTS: A quick antibody response and higher IgG2a/IgE ratio were observed with PM-allergoids. Moreover, stronger specific proliferative responses were seen in both submandibular LNs and spleen cells assayed in vitro. This was accompanied by a higher IFNγ/IL-4 ratio with a quick IL-10 production by submandibular LN cells. An increase in CD4+ CD25high FOXP3+ Treg cells was detected in LNs and spleen of mice treated with PM-allergoids. These allergoids were better captured than native allergens by antigen-presenting (CD45+ MHC-II+ ) cells obtained from the sublingual mucosa, including DCs (CD11b+ ) and macrophages (CD64+ ). Importantly, all the differential effects induced by PM-allergoids were abolished when using oxidized instead of nonoxidized PM-allergoids. CONCLUSION: Our results demonstrate for the first time that PM-allergoids administered through the sublingual route promote the generation of Th1 and FOXP3+ Treg cells in a greater extent than native allergens by mechanisms that might well involve their better uptake by oral antigen-presenting cells.

Occupational asthma caused by actinia equina

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Allergenome characterization of the mosquito Aedes aegypti.

BACKGROUND: Saliva and muscle-derived mosquito allergens have been purified and characterized. However, the complete set of allergens remains to be elucidated. In this study, we identified and characterized IgE-binding proteins from the mosquito species Aedes aegypti. METHODS: Serum was obtained from 15 allergic individuals with asthma and/or rhinitis and sensitized to mosquito. IgE binding was determined by ELISA. Total proteins from freeze-dried bodies of A. aegypti were extracted and IgE-reactive proteins were identified by 2D gel electrophoresis, followed by Western blot with pooled or individual sera. IgE-reactive spots were further characterized by mass spectrometry. RESULTS: Twenty-five IgE-reactive spots were identified, corresponding to 10 different proteins, some of which appeared as different variants or isoforms. Heat-shock cognate 70 (HSC-70) and tropomyosin showed IgE reactivity with 60% of the sera, lysosomal aspartic protease, and "AAEL006070-PA" (Uniprot: Q177P3) with 40% and the other proteins with <33.3% of the sera. Different variants or isoforms of tropomyosin, arginine or creatine kinase, glyceraldehyde-3-phosphate dehydrogenase (GPDH), calcium-binding protein, and phosphoglycerate mutase were also identified. The mixture of three allergens (Aed a 6, Aed a 8, and Aed a 10) seems to identify more than 80% of A. aegypti-sensitized individuals, indicating that these allergens should be considered when designing of improved mosquito allergy diagnostic tools. CONCLUSIONS: The newly identified allergens may play a role in the pathophysiology of mosquito allergy in the tropics, and some of them might be important arthropod-related proteins involved in cross-reactivity between A. aegypti and other allergenic arthropods.

MV140, a sublingual polyvalent bacterial preparation to treat recurrent urinary tract infections, licenses human dendritic cells for generating Th1, Th17, and IL-10 responses via Syk and MyD88.

Recurrent urinary tract infections (RUTIs) are one of the most common bacterial infectious diseases, especially in women. Antibiotics remain the mainstay of treatment, but their overuse is associated with antibiotic-resistant infections and deleterious effects in the microbiota. Therefore, alternative approaches are fully demanded. Sublingual immunization with MV140 (Uromune), a polyvalent bacterial preparation (PBP) of whole heat-inactivated bacteria, demonstrated clinical efficacy for the treatment of RUTIs, but the involved immunological mechanisms remain unknown. Herein, we demonstrated that MV140 endorses human dendritic cells (DCs) with the capacity to generate Th1/Th17 and IL-10-producing T cells by mechanisms depending on spleen tyrosine kinase (Syk)- and myeloid differentiation primary response gene 88 (MyD88)-mediated pathways. MV140-induced activation of nuclear factor κB (NF-κB) and p38 in human DCs is essential for the generated Th1/Th17 and IL-10 immune responses whereas c-Jun N-terminal Kinase (JNK) and extracellular-signal regulated kinase (ERK) contribute to Th1 and IL-10 responses, respectively. Sublingual immunization of BALB/c mice with MV140 also induces potent systemic Th1/Th17 and IL-10 responses in vivo. We uncover immunological mechanisms underlying the way of action of MV140, which might well also contribute to understand the rational use of specific PBPs in other clinical conditions with potential high risk of recurrent infections.

Safety of immunotherapy with glutaraldehyde modified allergen extracts in children and adults.

BACKGROUND: Glutaraldehyde-modified natural allergen extracts show significant reduction in the IgE-binding capacity and proteolytic activity. This allows the administration of higher doses in a shorter period of time, and to mix different allergen extracts. OBJECTIVE: Evaluate the safety of different concentrations and mixtures of glutaraldehyde-modified allergen extracts in a large group of paediatric and adult patients undergoing specific immunotherapy treatment. MATERIALS AND METHODS: 1855 patients (1156 adults and 699 children), suffering from rhinoconjunctivitis and/or asthma, participated in an observational multicentre cohort study, to evaluate the safety of immunotherapy using vaccines containing modified allergen extracts. Patients were monosensitised, or polysensitised, and received a therapeutic vaccine containing polymerised allergen extracts adsorbed onto aluminium hydroxide. Safety was assessed by recording all side reactions related to immunotherapy. RESULTS: The clinically relevant local reactions totalled 120, (90 immediate and 30 delayed) (1.02% of injections). Of them, 31 (0.26% of injections) occurred in children (26 immediate and 5 delayed) and 89 (0.76% of injections) in adults (64 immediate and 25 delayed). There were 38 systemic reactions. Eleven reactions were immediate (9 of grade 1 and 2 of grade 2) and 27 delayed (22 of grade 1 and 5 of grade 2). There were seven grade 2 systemic reactions (0.06% of the injections). No differences (P>0.05) in the number of reactions were observed between adults and children and between treatments were found in systemic reactions. All systemic reactions were mild and resolved spontaneously without the need of medication. CONCLUSION: Specific immunotherapy using natural modified allergen vaccines is safe to treat allergic patients, even at higher doses and in mixtures of unrelated allergen extracts. The percentage of adverse reactions detected is lower than those reported in the literature with native unmodified allergen extracts.

A 50-gene signature is a novel scoring system for tumor-infiltrating immune cells with strong correlation with clinical outcome of stage I/II non-small cell lung cancer.

PURPOSE: To identify a novel system for scoring intratumoral immune response that can improve prognosis and therapy decisions in early stage non-small cell lung cancer (NSCLC). METHODS/PATIENTS: Eighty-four completely resected stage I/II NSCLC without adjuvant therapy were classified by expression profiling using whole genome microarrays. An external cohort of 162 tumors was used to validate the results. Immune cells present in tumor microenvironment were evaluated semiquantitatively by CD20, CD79, CD3, CD8, CD4 and CD57 immunostaining. Univariate and multivariate analyses of variables associated with recurrence-free survival were performed. RESULTS: Initial molecular classification identified three clusters, one with significantly better RFS. A reduced two-subgroup classification and a 50-gene predictor were built and validated in an external dataset: high and low risk of recurrence patients (HR = 3.44; p = 0.001). Analysis of the predictor´s genes showed that the vast majority were related to a B/plasma cell immune response overexpressed in the low-risk subgroup. The predictor includes genes coding for unique B lineage-specific genes, functional elements or other genes that, although non-restricted to this lineage, have strong influence on B-cell homeostasis. Immunostains confirmed increased B-cells in the low-risk subgroup. Gene signature (p < 0.0001) and CD20 (p < 0.05) were predictors for RFS, while CD79 and K-RAS mutations showed a tendency. CONCLUSIONS: Favorable prognosis in completely resected NSCLC is determined by a B-cell-mediated immune response. It can be differently scored by a 50-gene expression profile or by CD20 immunostaining. That prognosis information not reflected by traditional classifications may become a new tool for determining individualized adjuvant therapies.

Sensitization to indigenous pollen and molds and other outdoor and indoor allergens in allergic patients from saudi arabia, United arab emirates, and Sudan.

BACKGROUND: : Airborne allergens vary from one climatic region to another. Therefore, it is important to analyze the environment of the region to select the most prevalent allergens for the diagnosis and treatment of allergic patients. OBJECTIVE: : To evaluate the prevalence of positive skin tests to pollen and fungal allergens collected from local indigenous plants or isolated molds, as well as other outdoor and indoor allergens in allergic patients in 6 different geographical areas in the Kingdom of Saudi Arabia (KSA), the United Arab Emirates, and Sudan. MATERIAL AND METHODS: : Four hundred ninety-two consecutive patients evaluated at different Allergy Clinics (276 women and 256 men; mean age, 30 years) participated in this study. The selection of indigenous allergens was based on research findings in different areas from Riyadh and adjoining areas. Indigenous raw material for pollen grains was collected from the desert near the capital city of Riyadh, KSA. The following plants were included: Chenopodium murale, Salsola imbricata, Rumex vesicarius, Ricinus communis, Artiplex nummularia, Amaranthus viridis, Artemisia monosperma, Plantago boissieri, and Prosopis juliflora. Indigenous molds were isolated from air sampling in Riyadh and grown to obtain the raw material. These included the following: Ulocladium spp., Penicillium spp., Aspergillus fumigatus, Cladosporium spp., and Alternaria spp. The raw material was processed under Good Manufacturing Practices for skin testing. Other commercially available outdoor (grass and tree pollens) and indoor (mites, cockroach, and cat dander) allergens were also tested. RESULTS: : The highest sensitization to indigenous pollens was detected to C. murale (32%) in Khartoum (Sudan) and S. imbricata (30%) and P. juliflora (24%) in the Riyadh region. The highest sensitization to molds was detected in Khartoum, especially to Cladosporium spp. (42%), Aspergillus (40%), and Alternaria spp. (38%). Sensitization to mites was also very prevalent in Khartoum (72%), as well as in Abu Dhabi (United Arab Emirates) (46%) and Jeddah (KSA) (30%). CONCLUSIONS: : The allergenicity of several indigenous pollens and molds derived from autochthonous sources was demonstrated. Prevalence studies in different regions of KSA and neighbor countries indicate different sensitization rates to these and other outdoor and indoor allergens.

Cluster immunotherapy with a glutaraldehyde-modified mixture of grasses results in an improvement in specific nasal provocation tests in less than 2.5 months of treatment.

BACKGROUND: Cluster immunotherapy is becoming increasingly used. It allows for a rapid build up phase and the administration of higher doses of allergen in a shorter period of time. OBJECTIVES: To evaluate the effect of short-term pre-seasonal immunotherapy using a glutaraldeyde-modified allergen vaccine in reducing specific nasal hyperreactivity in nasal challenge tests. MATERIALS AND METHODS: Thirty-three patients were selected. All patients had a positive history of allergic rhinitis and skin tests to grass pollen, although most of them (72.7%) were sensitized to other allergens as well. The study was conducted outside of the pollen season and the patients did not receive any pharmacological treatment during this period of time. Two randomized groups of patients were established; Group A: 22 patients (13 females and nine males) and Group B, 11 control patients (seven females and four males). Patients in Group A received immunotherapy with a vaccine containing 50% of the wild grasses Trisetum paniceum and Dactylis glomerata. All patients underwent titrated nasal provocation tests (NPT) before and after completion of the study (2.3 and 2.8 months for Groups A and B, respectively). The administration schedule consisted of 0.1 and 0.2 mL at day 1, followed by 0.3 and 0.5 mL at day 7, 0.5 mL after 2 weeks followed by 0.5 mL monthly. A single vial was used containing an allergen concentration of 10 000 TU/mL (105 microg of total protein and 24.6 microg of Group 1 plus 5 allergens/mL). A mean of 6.5 injections were administered to Group A patients between NPTs. RESULTS: There were no significant differences between both groups at the beginning of the study (P=0.48). At the end, only Group A patients needed significant greater threshold concentrations for a positive NPT than at the beginning (P=0.002). CONCLUSIONS: A short-term cluster pre-seasonal inmunotherapy with a modified vaccine containing a mixture of grass pollen is effective as determined by an objective measure after only a mean 2.3 months of treatment.

Involvement of IFNbeta on IFNgamma and nitric oxide (NO) production by bone marrow (BM) cells in response to lipopolysaccharide.

Bone marrow (BM) cells fractioned in Percoll gradients yield a low-density fraction (Fr3) highly enriched in suppressor activity. Previously, it has been demonstrated that BM associated suppressor activity was mediated by early myeloid cells, through a mechanism dependent on endogenous IFNgamma and nitric oxide production after bacterial stimuli, e.g. lipopolysaccharide (LPS). However, the mechanism(s) through which the IFNgamma is produced in BM has not yet been fully elucidated. Therefore, in the present study we investigated the involvement of IL-12, IL-18 and IFNbeta on the production of IFNgamma and nitric oxide in cultures of BM Fr3 cells, and characterized the IFNgamma-producing cells, in response to LPS. The results show that both IL-12 and IFNbeta, but not IL-18, are involved on IFNgamma production. However, only IFNbeta appears to be critical on nitric oxide production. Furthermore, we found that cells of the Thy1.2+CD3+ phenotype produce IFNgamma and are tightly involved on nitric oxide production by BM Fr3 cells. In conclusion, IFNbeta appears to be critical on IFNgamma- and nitric oxide production by BM cells in response to LPS, through a mechanism that is dependent on Thy1.2+CD3+ IFNgamma-producing cells.

Living in towers as risk factor of pollen allergy.

BACKGROUND: The effects of fluctuations in pollen counts have important implications for health services. Little research on the clinical implications of the vertical distribution of pollen in allergy symptoms has been carried out. METHODS: We have investigated the allergic symptoms of a population of 17 171 patients coming from our health area (Valladolid, Spain) and living in the city and villages. We compared the prevalence of sensitization to different pollens: Graminae, trees and shrub in relation with the floor of the building where they were living. RESULTS: Relative risk of pollen sensitization (confidence index, CI 95%) was higher in patients who were living at high floors than in those patients who were living in lower floors or at street level, independently of rural or urban conditions The chi-square showed a lineal trend in this relationship in the case of sensitization to grass pollen: chi(2): 1794, P > 0.00001 CONCLUSIONS: On the basis of our local investigations, natural pollen sensitization appears to increase with height where the patient lives. This paper reports clinical results on the influence of vertical pollen distribution in pollen allergy.

Trisetum paniceum (wild oats) pollen counts and aeroallergens in the ambient air of Madrid, Spain.

BACKGROUND: Madrid has a short but intensive grass pollen season, in which 79% of the total grass pollen load is released from the middle of May to the middle of June. The main objectives of this study were to quantify Trisetum paniceum (wild oats) aeroallergen in the atmosphere in Madrid from February to December 1996 and to correlate the aeroallergen concentrations with grass pollen counts. METHODS: Two different samplers were used to assess allergen exposure; a Burkard spore trap was used to collect pollen grains and a high-volume air sampler to collect airborne particles. A total of 182 air filters were collected and extracted in 1 ml of PBS and analysed by ELISA inhibition, using pooled sera from highly allergic individuals. RESULTS: T. paniceum aeroallergens were detected not only during the grass pollen season, but also before and after. Wild oat allergens had two main peaks of 1 and 1.9 microg/m(3), occurring in late May and July, respectively. The time series analysis established the existence of lags between the two main variables pollen counts and aeroallergen activity. Analysis of the data by the Spearman rank test and linear regression showed a weak correlation between grass allergenic activity and grass pollen counts (Spearman's rho = 0.29). Data obtained from time series analysis demonstrated that grass allergenic activity correlated strongly with current and 5-week-old grass pollen grain counts (r(2) = 0.73). CONCLUSIONS: Wild oats allergenic activity was detected during the entire year and not only during the pollen season. This fact is an important aspect to be considered in the clinical follow-up and treatment of grass pollen-sensitised patients in Madrid.

La producción de óxido nítrico por células supresoras mieloides puede ser resistente o sensible a la acción de los glucocorticoides dependiendo del tipo de co-estimulación. El efecto de la señalización a través de endotoxina frente al TNF-alfa / Sensitivity of nitric oxide production by myeloid suppressor cells to glucocorticoids depends on the type of stimulation

Las células supresoras mieloides producen una gran cantidad de óxido nítrico (NO) cuando son activadas con IFN más otras señales co-estimuladoras. Hemos estudiado el efecto inhibidor de los glucocorticoides (GC) sobre esta producción cuando las células se co-estimulan con endotoxina (LPS) o TNF. Los resultados muestran que el NO inducido por IFN en presencia de LPS (rango 0,1 - 10 µg/mL) es altamente resistente a la acción inhibidora de los GC (10- 6, 10- 7 M). En estos cultivos el TNF endógeno no es requerido para esa producción, como se evidencia en ensayos de neutralización. Por el contrario, el NO que se induce con IFN en presencia de cantidades mínimas de LPS (1 ng/mL) es muy sensible a la acción inhibidora de los GC. En estos cultivos, el TNF endógeno es necesario para esa inducción. En ausencia de LPS la producción de NO también es sensible a los GC cuando las señales co-estimuladoras dependen de TNF (TNF, TNF-RI, o CD40). Estos resultados indican que la producción NO por las células supresoras mieloides activadas con IFN muestran una sensibilidad muy diferente a los GC que depende del tipo de señales de co-estimulación presentes. Mientras que esta producción es resistente a los GC cuando las células son co-estimuladas con endotoxina por una vía independiente de TNF, la producción de NO es muy sensible a los GC si la co-estimulación depende de esta vía. (AU)

Cyclophosphamide induces the development of early myeloid cells suppressing tumor cell growth by a nitric oxide-dependent mechanism.

Adoptive immunotherapy with cyclophosphamide (Cy) increases the host resistance against tumor growth. The precise mechanism(s) by which this therapy enhances tumor suppression is unclear. Cy induces the development of early myeloid cells that may be strongly antiproliferative through NO production. These cells are similar to the natural suppressor cells found in normal bone marrow with a potential antitumor effect. Here we have addressed whether the development of NO-producing cells may be involved in this tumor resistance in Cy-treated mice. The results show a synergism between Cy treatment and tumor-specific lymphocytes transferred systemically (i.v.) or locally (Winn's assay) that results in a strong tumor suppression. Inhibition of NO production by N(G)-monomethyl-L-arginine at the site of tumor inoculation results in a loss of the protection achieved by the combined therapy. Cy-treated mice develop splenic early myeloid (CD11b, Gr-1, CD31 (ER-MP12), ER-MP20, ER-MP54) cells producing large amounts of NO upon T cell-derived signals (IFN-gamma plus CD40 ligation) able to inhibit tumor cell growth in vitro. Early myeloid cells (ER-MP54(+)) and cells expressing inducible NO synthase are increased at the site of tumor challenge in mice treated with the combined therapy, but not in those treated with Cy or immune cell transfer alone. Thus, Cy induces the expansion of early myeloid cells, inhibiting tumor cell growth by a mechanism involving NO. Both the recruitment and the activation of these myeloid cells at the site of tumor challenge appear to be dependent on the presence of tumor-specific lymphocytes.

Cómo interpretar los recuentos de pólenes / How to interpret pollen counts

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Early myeloid cells are high producers of nitric oxide upon CD40 plus IFN-gamma stimulation through a mechanism dependent on endogenous TNF-alpha and IL-1alpha.

Bone marrow contains nonadherent low-density wheat germ agglutinin-positive (Fr3-WGA(+)) cells that release large amounts of NO and show natural suppressor activity if stimulated with activated T cells. We have assessed the involvement of CD40-derived signals in NO production and their cytokine requirements. Production of NO by Fr3-WGA(+) cells in co-culture with activated T cells is inhibited by a competing CD40 soluble fusion protein. Fr3-WGA(+) cells express the inducible NO synthase (iNOS) and release NO following CD40 plus IFN-gamma activation. Production of NO through CD40 is strictly dependent on endogenous TNF-alpha and / or IL-1alpha, since it is inhibited by neutralizing these cytokines or blocking the TNF receptor (p55). Both cytokines are transcribed when Fr3-WGA(+) cells are stimulated by CD40 signaling plus IFN-gamma, although TNF-alpha remains below detection limits in stimulated Fr3-WGA(+) cell cultures. Phenotypic studies combined with data on intracellular iNOS expression and cell sorting indicate that NO-producing cells are CD40, CD31 (ER-MP12), CD11b (Mac-1)low, ER-MP20 (Ly-6C) and Gr-1 (Ly-6G) positive, consistent with myeloid progenitors. The results point to early myeloid cells as an important cell source of NO once triggered by activated T cells through CD40 and IFN-gamma-derived signals, in a mechanism involving the production of TNF-alpha and / or IL-1alpha.