In Vivo Genotoxicity and Cytotoxicity Kinetics of Trimethoprim Sulfamethoxazole in Well-nourished and Undernourished Young Rats.

BACKGROUND/AIM: Undernutrition is a serious health problem prevalent in poor countries, affecting millions of people worldwide, especially young children, pregnant women, and sick elderly individuals. This condition increases vulnerability to infections, leading to widespread use of antibiotic treatments in undernourished populations. The objective of the present study was to determine the in vivo genotoxic and cytotoxic effects of trimethoprim-sulfamethoxazole (TMP-SMX) treatment according to nutritional conditions. MATERIALS AND METHODS: The effects of TMP-SMX treatment were measured by analyzing the kinetics of micronucleated reticulocytes (MN-RET) induced in the peripheral blood of young, well-nourished (WN) and undernourished (UN) rats. RESULTS: In the WN group, two distinct peaks of MN-RET were observed, while the UN group had a significantly higher basal frequency of MN-RET compared to the WN group and only a later peak. Reticulocyte (RET) frequency slightly decreased in WN, indicating a poor cytotoxic effect. In contrast, in the UN, the treatment caused a significant increase in RET frequency. The results indicate that SMX's aromaticity index decreases when formed with TMP, suggesting potentially fewer toxic effects. CONCLUSION: In vivo TMP-SMX produces two MN-RET induction peaks in WN animals, indicating two DNA damage induction mechanisms and consequent micronucleus production. The UN rats did not display the two peaks, indicating that the first MN induction mechanism did not occur in UN, possibly due to pharmacokinetic effects, decreased metabolism or effects on cell proliferation. TMP-SMX has a slight cytotoxic effect on WN. In contrast, in the UN, the antibiotic treatment seems to favor early erythropoiesis.

Duchenne muscular dystrophy: RANK/RANKL/OPG (receptor activator of nuclear factor-kB/RANK ligand/osteoprotegerin) system and glucocorticoids.

Duchenne muscular dystrophy (DMD) is an X-linked inherited disorder. Patients present with decreased bone mineral density (BMD) due to glucocorticoid therapy and progressive muscle weakness. Bone remodeling allows bone volume and structure to be maintained and controlled by local and systemic factors. These include the receptor activator of the nuclear factor-kB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, a determining pathway in the balance between bone formation and resorption. Disruptions in this complex, caused by factors such as glucocorticoids, can affect bone metabolism. The extensive action of the RANK/RANKL/OPG pathway suggests an influence on dystrophic muscle pathophysiology. This review aimed to highlight some aspects of the RANK/RANKL/OPG system, the effect of glucocorticoids on this pathway, and the pathophysiology of the patient with DMD.

La distrofia muscular de Duchenne (DMD) es un trastorno hereditario ligado al cromosoma X. Los pacientes presentan una disminución de la densidad mineral ósea (DMO) debido a los efectos adversos del tratamiento con glucocorticoides y a la debilidad muscular progresiva. El remodelado óseo permite mantener el volumen y la estructura ósea, proceso controlado por factores locales y sistémicos. Entre ellos destaca el sistema del receptor activador del factor nuclear-kB (RANK), su ligando natural RANKL (RANKL) y la osteoprotegerina (OPG), una vía determinante en el equilibrio entre la resorción y formación ósea. Las alteraciones en este complejo, originadas por factores como los glucocorticoides, pueden afectar el metabolismo óseo. La amplia acción de RANKL y OPG ha sugerido una influencia en la fisiopatología de la DMD. El objetivo de esta revisión fue destacar algunos aspectos del sistema RANK/RANKL/OPG, el efecto de los glucocorticoides en esta vía y la fisiopatología del paciente con DMD.

Duchenne muscular dystrophy: RANK/RANKL/OPG (receptor activator of nuclear factor-kB/RANK ligand/osteoprotegerin) system and glucocorticoids / Distrofia muscular de Duchenne: el sistema RANK/RANKL/OPG (receptor activador del factor nuclear-kB/ligando de RANK/osteoprotegerina) y glucocorticoides

Abstract Duchenne muscular dystrophy (DMD) is an X-linked inherited disorder. Patients present with decreased bone mineral density (BMD) due to glucocorticoid therapy and progressive muscle weakness. Bone remodeling allows bone volume and structure to be maintained and controlled by local and systemic factors. These include the receptor activator of the nuclear factor-kB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, a determining pathway in the balance between bone formation and resorption. Disruptions in this complex, caused by factors such as glucocorticoids, can affect bone metabolism. The extensive action of the RANK/RANKL/OPG pathway suggests an influence on dystrophic muscle pathophysiology. This review aimed to highlight some aspects of the RANK/RANKL/OPG system, the effect of glucocorticoids on this pathway, and the pathophysiology of the patient with DMD.

Resumen La distrofia muscular de Duchenne (DMD) es un trastorno hereditario ligado al cromosoma X. Los pacientes presentan una disminución de la densidad mineral ósea (DMO) debido a los efectos adversos del tratamiento con glucocorticoides y a la debilidad muscular progresiva. El remodelado óseo permite mantener el volumen y la estructura ósea, proceso controlado por factores locales y sistémicos. Entre ellos destaca el sistema del receptor activador del factor nuclear-kB (RANK), su ligando natural RANKL (RANKL) y la osteoprotegerina (OPG), una vía determinante en el equilibrio entre la resorción y formación ósea. Las alteraciones en este complejo, originadas por factores como los glucocorticoides, pueden afectar el metabolismo óseo. La amplia acción de RANKL y OPG ha sugerido una influencia en la fisiopatología de la DMD. El objetivo de esta revisión fue destacar algunos aspectos del sistema RANK/RANKL/OPG, el efecto de los glucocorticoides en esta vía y la fisiopatología del paciente con DMD.

Imidazole and nitroimidazole derivatives as NADH-fumarate reductase inhibitors: Density functional theory studies, homology modeling, and molecular docking.

Chagas disease is caused by Trypanosoma cruzi. Benznidazole and nifurtimox are drugs used for its therapy; nevertheless, they have collateral effects. NADH-fumarate (FUM) reductase is a potential pharmacological target since it is essential for survival of parasite and is not found in humans. The objectives are to design and characterize the electronic structure of imidazole and nitroimidazole derivatives at DFT-M06-2X level in aqueous solution; also, to model the NADH-FUM reductase and analyze its intermolecular interactions by molecular docking. Quantum-chemical descriptors allowed to select the molecules with the best physicochemical properties and lowest toxicity. A high-quality three-dimensional structure of NADH-FUM reductase was obtained by homology modeling. Water molecules do not have influence in the interaction between FUM and NADH-FUM reductase. The main hydrogen-binding interactions for FUM were identified in NADH, Lys172, and Arg89; while hydrophobic interactions in Phe479, Thr174, Met63. The molecules S3-8, S2-8, and S1-8 could be inhibitors of NADH-FUM reductase.

In vivo kinetics of the genotoxic and cytotoxic activities of cladribine and clofarabine.

The aim of the present in vivo study was to determine the kinetics of the genotoxic and cytotoxic activities of cladribine and clofarabine in mouse normoblasts using flow cytometry. Mice in groups of five were treated with cladribine or clofarabine. Blood samples were obtained from the mouse tails before treatment and every 8 hr posttreatment for 72 hr. These samples were cytometrically scored for micronucleated reticulocytes (RETs), and the percentage of RETs was determined. The results showed that clofarabine and cladribine have early cytotoxic effects that are related to the genotoxic effects reported in previous studies; the drugs have both complex long-lasting genotoxic and cytotoxic kinetic activity, with similar profiles that suggest a relationship between the genotoxic and cytotoxic parameters. The initial genotoxkinetics timing of clofarabine is equivalent to those of difluorodeoxycytidine, likely because both agents inhibit DNA polymerase. Clofarabine shows a higher genotoxic and cytotoxic efficiency than cladribine, in agreement with previous results.

Phosphorylated ATM and H2AX in T and B lymphocytes from rats with moderate and severe malnutrition.

Protein calorie malnutrition (PCM) occurs when insufficient nutrients are consumed to satisfy the biological needs of an organism. The literature supports the relationship between malnutrition and DNA damage, and among the injuries to genetic material, DNA double-strand breaks (DSBs) are the most dangerous. This study aimed to determine whether the ability of splenic and peripheral blood T and B lymphocytes from nursing rats to recognize DSB-induced DNA damage is affected by PCM. Wistar strain rats were used, and experimental malnutrition was induced by creating food competition during lactation by increasing the number of offspring per wet nurse. Due to its high specificity, the phosphorylated H2AX variant histone assay associated with pATM (Ser1981) combined with flow cytometry was herein used to demonstrate the impact of malnutrition on the DNA damage response. Flow cytometry data indicated that splenic T and B lymphocytes from rats with severe PCM have the capacity to detect genetic material damage, as shown by an increased number of pATM + cells and altered signaling pathway continuity. Collectively, these data suggest that severe malnutrition compromises the continuity of the DNA damage response.

In vivo Characterization of the Radiosensitizing Effect of a Very Low Dose of BrdU in Murine Cells Exposed to Low-Dose Radiation.

The aim of the present study was to characterize the in vivo radiosensitizing effect of a very low dose of bromodeoxyuridine (BrdU) in mice exposed to low-dose radiation by establishing the following: (1) the radiosensitizing effect during DNA synthesis using single-cell gel electrophoresis (SCGE) in murine bone marrow cells, and (2) the number and timing of the mechanisms of genotoxicity and cytotoxicity, as well as the correlation of both end points, using flow cytometry analysis of the kinetics of micronucleus induction in reticulocytes. Groups of mice received intraperitoneal injections of 0.125 mg/g of BrdU 24 h prior to irradiation with 0.5 Gy of 60 Co gamma rays. DNA breaks measured using SCGE were determined at 30 min after exposure to radiation. The kinetics of micronucleated reticulocyte (MN-RET) induction was determined every 8 h after irradiation up to 72 h. The results from both experimental models indicated that low-level BrdU incorporation into DNA increased the sensitivity to 0.5 Gy of radiation, particularly in the S phase. The formation of micronuclei by gamma rays was produced at three different times using two main mechanisms. In the BrdU-substituted cells, the second mechanism was associated with a high cytotoxic effect that was absent in the irradiated BrdU-unsubstituted cells. The third mechanism, in which micronucleus formation was increased in irradiated substituted cells compared with the irradiated nonsubstituted control cells, was also related to an increase in cytotoxicity. Environ. Mol. Mutagen. 60:534-545, 2019. © 2019 Wiley Periodicals, Inc.

Assessment of micronucleus and oxidative stress in peripheral blood from malnourished children.

INTRODUCTION: malnutrition is one of the most common health problems among children in underdeveloped countries, including Mexico. Previous studies have indicated increased genetic damage in malnourished humans and animal models, but the essential mechanisms remain unclear. In the present study, we assessed the effects of malnutrition on the frequency of micronucleus (MN) in reticulocytes (RET) from the peripheral blood of well-nourished uninfected (WN), well-nourished infected (WNI), moderately malnourished infected (UNM) and severely malnourished infected (UNS) children. Moreover, lipid peroxidation and the antioxidant status were evaluated to investigate the role of oxidative processes in malnutrition-associated genotoxicity. METHODS: the antioxidant status of the study population was determined by measuring superoxide dismutase (SOD) in the red blood cells and glutathione peroxidase (GPX) in whole blood. RESULTS: the UNS and UNM groups have increased percentages of MN-RET compared to the WNI group. Moreover, the data showed a significant increase in lipid peroxidation and a decrease in erythrocyte SOD activity and GPX activity in the malnourished group compared to the well-nourished infected children. CONCLUSION: the data suggest that the antioxidant system was impaired in the cells of malnourished children and that oxidative stress causes a significant increase in DNA damage, as evaluated by the MN-RET frequency.

Assessment of micronucleus and oxidative stress in peripheral blood from malnourished children / Evaluación de micronúcleos y estrés oxidante en sangre periférica de niños desnutridos

Introduction: malnutrition is one of the most common health problems among children in underdeveloped countries, including Mexico. Previous studies have indicated increased genetic damage in malnourished humans and animal models, but the essential mechanisms remain unclear. In the present study, we assessed the effects of malnutrition on the frequency of micronucleus (MN) in reticulocytes (RET) from the peripheral blood of well-nourished uninfected (WN), well-nourished infected (WNI), moderately malnourished infected (UNM) and severely malnourished infected (UNS) children. Moreover, lipid peroxidation and the antioxidant status were evaluated to investigate the role of oxidative processes in malnutrition-associated genotoxicity. Methods: the antioxidant status of the study population was determined by measuring superoxide dismutase (SOD) in the red blood cells and glutathione peroxidase (GPX) in whole blood. Results: the UNS and UNM groups have increased percentages of MN-RET compared to the WNI group. Moreover, the data showed a significant increase in lipid peroxidation and a decrease in erythrocyte SOD activity and GPX activity in the malnourished group compared to the well-nourished infected children. Conclusion: the data suggest that the antioxidant system was impaired in the cells of malnourished children and that oxidative stress causes a significant increase in DNA damage, as evaluated by the MN-RET frequency

Introducción: la desnutrición es uno de los principales problemas de salud entre los niños de los países en desarrollo, incluido México. Estudios previos han mostrado que existe un incremento en el daño genético en humanos y modelos animales desnutridos, pero los mecanismos por los que se desencadena aún son poco claros. En el presente estudio, evaluamos los efectos de la desnutrición en la frecuencia de micronúcleos (MN) en reticulocitos (RET) de sangre periférica de niños bien nutridos no infectados (WN), bien nutridos infectados (WNI), desnutridos moderados infectados (UNM) y con desnutrición severa e infecciones (UNS). Asimismo, se evaluaron la lipoperoxidación y la capacidad antioxidante para investigar el papel del proceso oxidativo en la genotoxicidad asociada a la desnutrición. Métodos: la capacidad antioxidante de la población de estudio fue determinada midiendo la superóxido-dismutasa (SOD) en los eritrocitos y glutatión peroxidasa (GPX) en sangre completa. Resultados: los niños UNS y UNM tienen alto porcentaje de MN-RET comparados con el grupo WNI. Además, los datos mostraron un incremento significativo en la lipoperoxidación y disminución en la actividad de SOD y GPX en el grupo de niños desnutridos comparados con el grupo de niños bien nutridos infectados. Conclusión: los datos sugieren que el sistema antioxidante está deteriorado en las células de los niños desnutridos y que el estrés oxidante causa un incremento significativo en el daño al ADN, el cual se refleja en el incremento en la frecuencia de RET-MN

Trimethoprim-sulfamethoxazole treatment increases the Pig-a mutant frequency in peripheral blood from severely malnourished rats.

Severe malnutrition is a complex condition that increases susceptibility to infections. Thus, drugs are extensively used in malnutrition cases. In the present study, we assessed the mutagenic effects of combined trimethoprim and sulfamethoxazole (TMP-SMX) treatment in undernourished (UN) and well-nourished (WN) rats. Six-week-old UN and WN Han-Wistar rats were treated with TMP-SMX at a daily dose of 10 mg/kg/d TMP and 50 mg/kg/d SMX for 5 or 10 days. Blood was collected from the tail vein one day before (day -1) and 15, 30, and 45 days after TMP-SMX administration. The Pig-a mutant frequencies (MFs) in peripheral blood reticulocytes (RETs) and erythrocytes (RBCs) were measured through flow cytometry. Severe malnutrition increased the basal MFs in RETs (RET CD59-) and RBC (RBCs CD59-). These findings support the hypothesis that severe malnutrition is mutagenic even in the absence of exposure to an exogenous mutagen. UN and WN rats treated for 5 or 10 consecutive days with TMP-SMX had significantly increased and sustained Pig-a mutant frequencies, demonstrating the mutagenic effects of this drug.

Serum cytokines and activation ex vivo of CD4+ and CD8+ T cells in chagasic chronic Mexican patients

The clinical manifestations of human Chagas disease are associated with several factors, including immunological alterations, in this regard, many studies propose that tissue damage might be more severe in the absence of immune regulatory mechanisms, other factors are the genetic background of host and parasite. Trypanosoma cruzi population is genetically, biochemistry and pathogenic diverse along the Latin-America continent and phylogenetic ally are divided into six intra-species lineages TcI-VI. The TcI lineage has a wide distribution with heterogeneous virulence and pathogenesis within strains. In Mexico, the main circulating lineage is TcI in human infections. We analyzed intracytoplasmic cytokines of unstimulated peripheral T lymphocytes, and the level of cytokines (IL-2, IL-4, IL-12, IL-10, IFN-γ and sIL-2R) in the serum of Mexican chagasic subjects. The population studied consisted of 15 asymptomatic individuals, 17 patients with chronic chagasic cardiopathy (CCC), 20 patients with cardiopathy but negative serology for T. cruzi, and 10 healthy subjects. The analysis of CD4+ cells revealed that CCC and asymptomatic patients have higher CD25+ and CD69 activation markers than controls. The Th1 subset (CD4+/IFN- γ +) was higher in CCC than in asymptomatic and control subjects, whereas Th2 subset was markedly high in asymptomatic subjects. Circulating cytokines were below level detection with the exception of IL-2 and sIL-2R. Infection with Mexican Trypanosoma cruzi strains in asymptomatic chagasic subjects have a tendency for a Th2 response with higher CD8+/IFN-γ T cells. In contrast, CCC patients have low levels of intracellular IFN- γ and IL-2 cytokines. In both groups circulating serum cytokines are below the detectable level.

Moderate malnutrition in rats induces somatic gene mutations.

The relationship between malnutrition and genetic damage has been widely studied in human and animal models, leading to the observation that interactions between genotoxic exposure and micronutrient status appear to affect genomic stability. A new assay has been developed that uses the phosphatidylinositol glycan class A gene (Pig-a) as a reporter for measuring in vivo gene mutation. The Pig-a assay can be employed to evaluate mutant frequencies (MFs) in peripheral blood reticulocytes (RETs) and erythrocytes (RBCs) using flow cytometry. In the present study, we assessed the effects of malnutrition on mutagenic susceptibility by exposing undernourished (UN) and well-nourished (WN) rats to N-ethyl-N-nitrosourea (ENU) and measuring Pig-a MFs. Two week-old UN and WN male Han-Wistar rats were treated daily with 0, 20, or 40mg/kg ENU for 3 consecutive days. Blood was collected from the tail vein one day before ENU treatment (Day-1) and after ENU administration on Days 7, 14, 21, 28, 35, 42, 49, 56 and 63. Pig-a MFs were measured in RETs and RBCs as the RET(CD59-) and RBC(CD59-) frequencies. In the vehicle control groups, the frequencies of mutant RETs and RBCs were significantly higher in UN rats compared with WN rats at all sampling times. The ENU treatments increased RET and RBC MFs starting at Day 7. Although ENU-induced Pig-a MFs were consistently lower in UN rats than in WN rats, these differences were not significant. To understand these responses, further studies should use other mutagens and nucleated surrogate cells and examine the types of mutations induced in UN and WN rats.

Malnutrition and infection influence the peripheral blood reticulocyte micronuclei frequency in children.

Malnutrition is a serious public health problem that affects approximately one third of all children. Developing countries have the highest incidence of malnourished children, and approximately 60% of deaths that occur in children under five are directly related to malnutrition and associated diseases. The relationship between malnutrition and genetic damage has been widely studied in humans and animal models. The micronucleus (MN) assay is useful in detecting chromosome damage induced by several factors. The aim of this study was to evaluate the effects of infection and malnutrition on the frequency of MN in erythrocytes from the peripheral blood of well-nourished, uninfected (WN) and well-nourished, infected (WNI) children, and moderately malnourished (UNM) and severely malnourished (UNS) children, both with infection, using a flow cytometric analysis technique. The percentage of reticulocytes (RETs) was significantly higher (1.5-fold) in WNI children than well-nourished controls. In addition, the UNS group had a 2.2-fold increase in the percentage of RETs compared to the WNI group. The frequency of micronucleated reticulocytes (MN-RETs) was 2.5 times greater, in WNI group compared to the WN group. These frequencies were significantly higher (1.7- and 2.1-fold) in UNM and UNS, respectively, compared to the WNI group. The results suggest that infection and malnutrition induce DNA damage in children.

Biodirected mutagenic chemical assay of PM(10) extractable organic matter in Southwest Mexico City.

The concentration of breathable particles (PM(10)) in urban areas has been associated with increases in morbidity and mortality of the exposed populations, therein the importance of this study. Organic compounds adsorbed to PM(10) are related to the increased risk to human health. Although some studies have shown the lack of correlation between specific mutagenic compounds in an organic complex mixture (OCM) and the mutagenic response in several bioassays, the same organic compounds selectively separated in less complex groups can show higher or lower mutagenic responses than in the OCM. In this study, we fractionated the OCM, from the PM(10) in four organic fractions of increasing polarity (F1-F4). The Salmonella bioassay with plate incorporation was applied for each one using TA98, with and without S9 (mammalian metabolic activation), and YG1021 (without S9) strains. The most polar fraction (F4) contained the greatest mass followed by F1 (non-polar), F2 and F3 (moderately polar). The concentrations of the OCM as well as the F4 were the only variables correlated with PM(10), atmospheric thermal inversions, fire-prone area, NO(2), SO(2), CO, rain and relative humidity. This indicated that polar organic compounds were originated in gas precursors formed during the atmospheric thermal inversions as well as the product of the incomplete combustion of vehicular exhausts and of burned vegetation. The percentages of the total PAH, and the individual PAH with molecular weight > or = 228 g mol(-1) (except retene) correlated with the percentages of indirect-acting mutagenicity in TA98+S9. The percentages of the total nitro-PAH and most of the analyzed individual nitro-PAH correlated with percentages of the direct-acting mutagenicity in both TA98-S9 and YG1021, the latter being more sensitive. In general, the highest mutagenic activity (indirect and direct) was found in F3 (moderately polar) and in F4 (polar). The non-polar fraction (F1) did not exhibit any kind of mutagenicity. In 77% of the cases, mutagenic activity was higher in the sum fractions with respect to their OCM. The combinations between F1, F2 and F4, with F3 under different or equal proportions suggested that mutagenicity reduction, in the combined matter of January (with TA98+S9 and YG1021) and of May (with YG1021), was due to concentrations of mutagens and non-mutagens in each fraction, and not to an antimutagenic effect. The organic compounds present in the non-polar fractions showed no antagonism, inhibition or reduction in the most mutagenic fractions in both indirect- and direct-acting mutagenicity, and the less polar organic compounds in F3 reduced mutagenicity in F4, in both months.

Electronic structure and physicochemical properties characterization of the amino acids 12-26 of TP53: a theoretical study.

PNC-27, a synthetic peptide, is derived from the TP53-HDM2 binding domain that include TP53 amino acids 12-26 linked with 17 amino acids from the antennapedia protein transference domain. This peptide induces membrane rupture in tumor cells through toroidal pores formation and has motivated several experimental studies; nonetheless, its mechanism of biological action remains unknown to date. Herein, we present a theoretical study at the Hartree-Fock and density functional theory (B3LYP) levels of theory of TP53 protein residues 12-26 (PPLSQETFSDLWKLL) in order to characterize its electronic structure and physicochemical properties. Our results for atomic and group charges, fitted to the electrostatic potential (ESP) show important reactive sites (L14, S15, T18, S20, L25, and L26), suggesting that these amino acids are exposed to nucleophilic and electrophilic attacks. Analysis of bond orders, intramolecular interactions and of several global reactivity descriptors, such as ionization potentials, hardness, electrophilicity index, dipole moments, total energies, frontier molecular orbitals (HOMO-LUMO), and electrostatic potential, led us to characterize active sites and the electronic structure and physiochemical features that taken together may be important in understanding the specific selectivity for this peptides type's cancer-cell membrane lysis properties.

Differential effects of rapid eye movement sleep deprivation and immobilization stress on blood lymphocyte subsets in rats.

OBJECTIVES: There is growing evidence of the relationship between sleep and the immune response. Studies aimed at elucidating the function of rapid eye movement (REM) sleep have found it difficult to separate the effects due to REM sleep deprivation and the effects due to the stress produced by the deprivation procedure. It has been claimed that immobilization is the main stressor that the animals have to face during the deprivation process. In this study, we analyzed the effects of short-term (24 h) and long-term (240 h) REM sleep deprivation on the distribution of lymphocyte subsets in the peripheral blood of rats. In addition, these effects were compared with those obtained after both short- and long-term stress by immobilization. METHODS: Lymphocyte population bearing surface markers such as CD5 (T cells), CD45RA (B cells), CD4 (T helper/inducer cells), CD8 (T suppressor/cytotoxic cells) and CD161 (NK cells) were analyzed using monoclonal antibodies. Lymphocyte subsets were assessed by flow cytometry. RESULTS: Both short- and long-term REM sleep deprivation decreased the percentage of T lymphocytes and induced a significant increase in NK cells. Short-term immobilization induced only a significant increase in the percentage of B lymphocytes and a decrease in the percentage of T lymphocytes, while long-term immobilization did not elicit any change. CONCLUSION: The present results support the notion that REM sleep deprivation and immobilization stress each exert particular effects on the immune system. These data suggest that the characteristics of the immune response will depend on the nature of the behavioral manipulation.