Valores de referência hematológicos e bioquímicos para camundongos das linhagens C57BL/6, Swiss Webster e BALB/c

The use of animals in scientific research has contributed significantly to the development of science, promoting various advances in understanding the metabolic machinery and the discovery of treatments and preventive measures applied to human and veterinary medicine. The development and use of alternative methods is encouraged; however, in some situations, the use of animals in accordance with ethical policies is still required. Established hematological and clinical chemistry reference values in laboratory animals are essential to evaluate functional changes; however, there are few data in the literature on these values, being fundamentally a comparative basis. The aim of this investigation was the establishment of hematological and clinical chemistry reference values in common strains/stocks of mice used in animal experimentation. Blood profile (hemogram, reticulocytes and myelogram) and clinical chemistry serum determination of total protein, albumin, glucose, cholesterol, triglycerides, calcium and phosphorus were evaluated using C57BL/6, BALB/c and Swiss Webster mice, male, 2-3 months old. The results standardize reference intervals in animals reared in Laboratory Animal Facility, reflecting the expected condition in rodents subjected to scientific research.O uso de animais na pesquisa científica tem contribuído significativamente para o desenvolvimento da ciência, promovendo vários avanços na compreensão da maquinaria metabólica, bem como a descoberta de tratamentos e medidas preventivas aplicadas à medicina humana e veterinária. O desenvolvimento e utilização de métodos alternativos é encorajado, no entanto, em algumas situações, ainda é necessária a utilização de animais em conformidade com termos éticos. Estabelecer valores de referência hematológicos e bioquímicos para animais de laboratório é essencial para avaliar alterações funcionais, no entanto, existem poucos dados na literatura sobre estes valores, sendo fundamentalmente uma base comparativa. O presente trabalho foi delineado para estabelecer valores de referência hematológicos e bioquímicos em linhagens camundongos utilizados em pesquisa científica. Foram avaliados o perfil sanguíneo (hemograma, reticulócitos e mielograma) e a determinação bioquímica sérica de proteínas totais, albumina, glicose, colesterol, triglicerídeos, cálcio e fósforo. Foram utilizados camundongos C57BL/6, BALB/c e Swiss Webster, do sexo masculino, 2-3 meses de idade. Os resultados padronizam intervalos de referência em camundongos criados em Biotério, refletindo a condição esperada nesses animais submetidos à investigação científica

Endosteal niche participation in the hematopoiesis of mice submitted to protein malnourishment.

O nicho endosteal da medula óssea abriga as células-tronco hemopoéticas (CTH) em quiescência/autorrenovação. As CTH podem ser classificadas em dois grupos: células que reconstituem a hemopoese em longo prazo (LT-CTH) e curto prazo (CT-CTH). Investigamos, neste trabalho, os efeitos da desnutrição proteica (DP) no tecido ósseo e a participação do nicho endosteal na sinalização osteoblasto-CTH. Para tanto, utilizamos camundongos submetidos à DP induzida pelo consumo de ração hipoproteica. Os animais desnutridos apresentaram pancitopenia e diminuição nas concentrações de proteínas séricas e albumina. Quantificamos as CTH por citometria de fluxo e verificamos que os desnutridos apresentaram menor porcentagem de LT-CTH, CT-CTH e de progenitores multipotentes (PMP). Avaliamos a expressão das proteínas CD44, CXCR4, Tie-2 e Notch-1 nas LT-CTH. Observamos diminuição da expressão da proteína CD44 nos desnutridos. Isolamos as células LT-CTH por cell sorting e avaliamos a expressão gênica de CD44, CXCR4 e NOTCH-1. Verificamos que os desnutridos apresentaram menor expressão de CD44. Em relação ao ciclo celular, verificamos maior quantidade de LT-CTH nas fases G0/G1. Caracterizamos as alterações do tecido ósseo femoral, in vivo. Observamos diminuição da densidade mineral óssea e da densidade medular nos desnutridos. A desnutrição acarretou diminuição da área média das seções transversais, do perímetro do periósteo e do endósteo na cortical do fêmur dos animais. E na região trabecular, verificou-se diminuição da razão entre volume ósseo e volume da amostra e do número de trabéculas, aumento da distância entre as trabéculas e prevalência de trabéculas ósseas em formato cilíndrico. Avaliamos a expressão de colágeno, osteonectina (ON) e osteocalcina (OC) por imuno-histoquímica, e de osteopontina (OPN) por imunofluorescência no fêmur e verificamos diminuição da marcação para OPN, colágeno tipo I, OC e ON nos desnutridos. Evidenciamos, pela técnica do Picrosírius, desorganização na distribuição das fibras colágenas e presença de fibras tipo III nos fêmures dos desnutridos, além de maior número de osteoclastos evidenciados pela reação da fosfatase ácida tartarato resistente. Os osteoblastos da região femoral foram isolados por depleção imunomagnética, imunofenotipados por citometria de fluxo e cultivados em meio de indução osteogênica. Observamos menor positividade para fosfatase alcalina e vermelho de alizarina nas culturas dos osteoblastos dos desnutridos. Avaliamos, por Western Blotting, a expressão de colágeno tipo I, OPN, osterix, Runx2, RANKL e osteoprotegerina (OPG), e, por PCR em tempo real, a expressão de COL1A2, SP7, CXCL12, ANGPT1, SPP1, JAG2 e CDH2 nos osteoblastos isolados. Verificamos que a desnutrição acarretou diminuição da expressão proteica de osterix e OPG e menor expressão gênica de ANGPT1. Avaliamos a proliferação das células LSK (Lin-Sca1+c-Kit+) utilizando ensaio de CFSE (carboxifluoresceína succinimidil ester). Foi realizada cocultura de células LSK e osteoblastos (MC3T3-E1) na presença e ausência de anti-CD44. Após uma semana, verificamos menor proliferação das LSK dos desnutridos. O bloqueio de CD44 das LSK do grupo controle diminuiu a proliferação destas em três gerações. Entretanto, nos desnutridos, esse bloqueio não afetou a proliferação. Concluímos que a DP promoveu alterações no tecido ósseo e nas CTH. Entretanto, não podemos afirmar que as alterações observadas no sistema hemopoético foram decorrentes de alterações exclusivas do nicho endosteal.The bone marrow endosteal niche hosts hematopoietic stem cells (HSC) in quiescence/self-renewal. HSC can be classified into two groups: cells capable of renewing indefinitely (LT-HSC) or repopulating in the short term (ST-HSC). In this work, we investigated the effects of protein malnutrition (PM) on bone tissue and the involvement of the endosteal niche in osteoblast-CTH signaling. Therefore, we used mice subjected to PM induced by the consumption of hypoproteic feed. Malnourished animals presented pancytopenia and decreased concentration of serum protein and albumin. We quantified the HSC by flow cytometry and found that the malnourished ones had lower percentage of LT-HSC, ST-HSC and multipotent progenitors (MPP). We assessed the expression of the CD44, CXCR4, Tie-2 and Notch-1 proteins in LT-HSC. We observed decreased expression of CD44 protein with the malnourished ones. We isolated the LT-HSC cells by means of cell sorting and assessed the gene expression of CD44, CXCR4 and NOTCH-1. We found that malnutrition had lower expression of CD44. Regarding the cell cycle, we see greater amount of LT-HSC in the G0 and G1 phases. We characterized the changes of the femoral bone tissue in vivo. We observed a decrease in the bone mineral density and medullar density in malnourished animals. As for malnourished animals, the femoral cortical region showed a significant decrease in tissue area, periosteal and endosteal perimeter. The femoral trabecular region of malnourished animals showed decreased bone volume/tissue volume ratio, decreased trabecular number, increased trabecular separation and prevalence of rod-like trabeculae. We investigated the expression of collagen, osteonectin (ON) and osteocalcin (OC) by means of immunohistochemistry and the expression of osteopontin (OPN) by immunofluorescence and we found that malnourished animals showed decreased labeling for OPN, type I collagen, OC and ON in the cortical region of the femur. Picrosirius staining was used to analyze disorganization of collagen fibers and presence of type III fibers in the femurs of the malnourished. Cortical and trabecular regions of malnourished animals presented a higher number of osteoclasts as shown by tartrate-resistant acid phosphatase reaction. Moreover, osteoblasts were isolated from the femoral region by immunomagnetic depletion and immunophenotyped by flow cytometry and cultured in osteogenic induction medium. Results proved less positive for alkaline phosphatase and alizarin red in the cultures of osteoblasts of malnourished animals. We assessed, by means of Western blotting, type I collagen expression, OPN, osterix, Runx2, RANKL and osteoprotegerin (OPG) and, by real time PCR, the expression of COL1A2, SP7, CXCL12, ANGPT1, SPP1, JAG2 and CDH2 with the isolated osteoblasts. We found that malnutrition led to osterix and OPG decreased protein expression and lower ANGPT1 gene expression. We evaluated LSK cell (Lin-Sca1+c-Kit+) proliferation by CFSE (carboxyfluorescein succinimidyl ester). LSK cells and osteoblasts (MC3T3-E1) cocultures were performed in the presence and absence of anti-CD44. After a week, we found lower proliferation of LSK in the malnourished. The LSK CD44 blocking in the control group decreased the proliferation of these three generations. However, as for the malnourished, such blockage did not affect proliferation. We concluded that the PM has promoted changes in bone tissue and the CTH. However, we can\'t claim that the alterations observed in hematopoietic system were due to endosteal niche-only changes

Study s-nitrosation of Ras and participation of MAP kinases (ERK, JNK and p38) in THP-1 cell apoptosis induced by nitric oxide

Ras é uma proteína G monomérica que converte estímulos extracelulares em sinais bioquímicos intracelulares e controla uma variedade de processos biológicos, tais como, proliferação, diferenciação, adesão e morte celular por apoptose. Além da ativação mediada por fatores de crescimento e hormônios, Ras pode ser ativado pela interação com o óxido nítrico (NO·), um radical capaz de mediar processos de sinalização. Essa interação resulta na S-nitrosação do resíduo de cisteína 118 de Ras. Assim, propusemo-nos avaliar a participação da proteína Ras e das MAP quinases: ERK1/2, JNK e p38 no processo de apoptose de células THP-1 induzida pelo doador de NO·, S-nitrosoglutationa (SNOG). Para tanto, transfectamos células THP-1 com o plasmídeo que carrega o gene que codifica para a proteína Ras mutada, na qual o resíduo de cisteína 118 foi trocado por um resíduo de serina, o que tornou Ras não responsiva ao NO·. A apoptose foi evidenciada através da formação de corpos apoptóticos, exposição de fosfatidilserina e ativação de caspase-3. A modulação da apoptose via reação de S-nitrosação foi demonstrada através da diminuição estatisticamente significativa da exposição de fosfatidilserina nas células transfectadas com o plasmídeo p21 RasC118S quando comparadas com as células selvagens e parentais. A ativação da proteína Ras ocorreu após 5, 15 e 30 minutos da adição de SNOG nas células parentais; entretanto, nas células transfectadas com o plasmídeo p21 RasC118S não observamos resposta de ativação de Ras. A avaliação das MAP quinases revelou ativação de máxima de ERK após 4 horas e ativação máxima de JNK e p38 após 2 horas de incubação com SNOG. Em relação as MAP quinases nas células transfectadas, as células p21 RasC118S apresentaram diminuição apenas da ativação ERK, quando comparadas com as células p21RasWt. A utilização dos inibidores específicos de MEK, JNK e p38; PD09895, CEP11004 e SB22004, respectivamente demonstrou que apenas a inibição de ERK diminuiu significativamente a apoptose nas células THP-1. Concluímos que na apoptose de células THP-1 estimulada por NO·, o radical livre ativa Ras via S-nitrosação, que por sua vez, recruta ERK, MAP quinase participante desta cascata de sinalização. Finalmente, demonstramos que ERK exerce papel fundamental na condução do sinal de apoptose no modelo que estudamos.Ras is a monomeric small G protein that converts intracellular stimulus into intracellular biochemical signals. Ras controls a myriad of biological processes such as, proliferation, differentiation, adhesion and cell death by apoptosis. In addition to growth factor-mediated activation of Ras, nitric oxide (NO·) directly interacts with and activates Ras via S-nitrosation on a single cysteine residue (Cys118). Therefore, we investigated the participation of Ras and of the MAP kinases (ERK, JNK and p38) in the apoptosis of THP-1 cells induced by the NO· donor S-nitrosoglutathione (SNOG). For that, we transfected THP-1 cells with a plasmid that contains the gene that codifies for the mutated Ras protein, in which the cysteine residue 118 was replaced by a serine. Apoptosis was evidenced by apoptotic bodies formation, phosphatidylserine exposition and caspase-3 activation. Parental and wild type Ras transfected-THP-1 cells (Wt) exposed phosphatidylserine upon treatment with 1.0 mM SNOG. The importance of the S-nitrosation reaction in the process was evidenced by a decrease on phosphatidylserine exposition in the cells transfected with the plasmid p21RasC118S, as compared to parental and wild type cells. Ras activation occurred within the first 30 minutes after SNOG addition to parental cells. However in p21RasC118S transfected cells, we were unable to detect activation of Ras. Regarding the MAP kinases located downstream on the Ras-mediated signaling cascade, ERK activity was maximum after 4 hours incubation with the NO· donor. JNK and p38 MAP kinase followed different kinetics, displaying maximum activity after 2 hours incubation with SNOG. The use of specific inhibitors to MEK, JNK and p38; PD09895, CEP11004 and S822004 respectively has shown that only ERK inhibition has significantly decreased THP-1 cells apoptosis. We concluded that NO· induced apoptosis in THP-1 cells activating Ras by S-nitrosation and recruiting the MAP kinase ERK, a downstream element of this signaling cascade. Furthermore, our findings support a major role for ERK in the NO· mediated apoptosis of THP-1 cells

Study s-nitrosation of Ras and participation of MAP kinases (ERK, JNK and p38) in THP-1 cell apoptosis induced by nitric oxide

Ras é uma proteína G monomérica que converte estímulos extracelulares em sinais bioquímicos intracelulares e controla uma variedade de processos biológicos, tais como, proliferação, diferenciação, adesão e morte celular por apoptose. Além da ativação mediada por fatores de crescimento e hormônios, Ras pode ser ativado pela interação com o óxido nítrico (NO·), um radical capaz de mediar processos de sinalização. Essa interação resulta na S-nitrosação do resíduo de cisteína 118 de Ras. Assim, propusemo-nos avaliar a participação da proteína Ras e das MAP quinases: ERK1/2, JNK e p38 no processo de apoptose de células THP-1 induzida pelo doador de NO·, S-nitrosoglutationa (SNOG). Para tanto, transfectamos células THP-1 com o plasmídeo que carrega o gene que codifica para a proteína Ras mutada, na qual o resíduo de cisteína 118 foi trocado por um resíduo de serina, o que tornou Ras não responsiva ao NO·. A apoptose foi evidenciada através da formação de corpos apoptóticos, exposição de fosfatidilserina e ativação de caspase-3. A modulação da apoptose via reação de S-nitrosação foi demonstrada através da diminuição estatisticamente significativa da exposição de fosfatidilserina nas células transfectadas com o plasmídeo p21 RasC118S quando comparadas com as células selvagens e parentais. A ativação da proteína Ras ocorreu após 5, 15 e 30 minutos da adição de SNOG nas células parentais; entretanto, nas células transfectadas com o plasmídeo p21 RasC118S não observamos resposta de ativação de Ras. A avaliação das MAP quinases revelou ativação de máxima de ERK após 4 horas e ativação máxima de JNK e p38 após 2 horas de incubação com SNOG. Em relação as MAP quinases nas células transfectadas, as células p21 RasC118S apresentaram diminuição apenas da ativação ERK, quando comparadas com as células p21RasWt. A utilização dos inibidores específicos de MEK, JNK e p38; PD09895, CEP11004 e SB22004, respectivamente demonstrou que apenas a inibição de ERK diminuiu significativamente a apoptose nas células THP-1. Concluímos que na apoptose de células THP-1 estimulada por NO·, o radical livre ativa Ras via S-nitrosação, que por sua vez, recruta ERK, MAP quinase participante desta cascata de sinalização. Finalmente, demonstramos que ERK exerce papel fundamental na condução do sinal de apoptose no modelo que estudamos.Ras is a monomeric small G protein that converts intracellular stimulus into intracellular biochemical signals. Ras controls a myriad of biological processes such as, proliferation, differentiation, adhesion and cell death by apoptosis. In addition to growth factor-mediated activation of Ras, nitric oxide (NO·) directly interacts with and activates Ras via S-nitrosation on a single cysteine residue (Cys118). Therefore, we investigated the participation of Ras and of the MAP kinases (ERK, JNK and p38) in the apoptosis of THP-1 cells induced by the NO· donor S-nitrosoglutathione (SNOG). For that, we transfected THP-1 cells with a plasmid that contains the gene that codifies for the mutated Ras protein, in which the cysteine residue 118 was replaced by a serine. Apoptosis was evidenced by apoptotic bodies formation, phosphatidylserine exposition and caspase-3 activation. Parental and wild type Ras transfected-THP-1 cells (Wt) exposed phosphatidylserine upon treatment with 1.0 mM SNOG. The importance of the S-nitrosation reaction in the process was evidenced by a decrease on phosphatidylserine exposition in the cells transfected with the plasmid p21RasC118S, as compared to parental and wild type cells. Ras activation occurred within the first 30 minutes after SNOG addition to parental cells. However in p21RasC118S transfected cells, we were unable to detect activation of Ras. Regarding the MAP kinases located downstream on the Ras-mediated signaling cascade, ERK activity was maximum after 4 hours incubation with the NO· donor. JNK and p38 MAP kinase followed different kinetics, displaying maximum activity after 2 hours incubation with SNOG. The use of specific inhibitors to MEK, JNK and p38; PD09895, CEP11004 and S822004 respectively has shown that only ERK inhibition has significantly decreased THP-1 cells apoptosis. We concluded that NO· induced apoptosis in THP-1 cells activating Ras by S-nitrosation and recruiting the MAP kinase ERK, a downstream element of this signaling cascade. Furthermore, our findings support a major role for ERK in the NO· mediated apoptosis of THP-1 cells

The nitric oxide-sensitive p21Ras-ERK pathway mediates S-nitrosoglutathione-induced apoptosis

p21Ras protein plays a critical role in cellular signaling that induces either cell cycle progression or apoptosis. Nitric oxide (NO) has been consistently reported to activate p21Ras through the redox sensitive cysteine residue (118). In this study, we demonstrated that the p21Ras-ERK pathway regulates THP-1 monocyte/macrophage apoptosis induced by S-nitrosoglutathione (SNOG). This was apparent from studies in THP-1 cells expressing NO-insensitive p21Ras (p21Ras(C118S)) where the pro-apoptotic action of SNOG was almost abrogated. Three major MAP kinase pathways (ERK, JNK, and p38) that are downstream to p21Ras were investigated. It was observed that only the activation of ERK1/2 MAP kinases by SNOG in THP-1 cells was attributable to p21Ras. The inhibition of the ERK pathway by PD98059 markedly attenuated apoptosis in SNOG-treated THP-1 cells, but had a marginal effect on SNOG-treated THP-1 cells expressing NO-inserisitive p21Ras. The inhibition of the JNK and p38 pathways by selective inhibitors had no marked effects on the percentage of apoptosis. The induction of p21Waf1 expression by SNOG was observed in THP-1 cells harboring mutant and wild-type p21Ras, however in cells expressing mutant Ras, the expression of p21Waf1 was significantly attenuated. The treatment of THP-1 cells expressing wild-type p21Ras with PD98059 resulted in significant attenuation of p21Waf1 expression. These results indicate that the redox sensitive p21Ras-ERK pathway plays a critical role in sensing and delivering the pro-apoptotic signaling mediated by SNOG. (C) 2008 Elsevier Inc. All rights reserved

The nitric oxide-sensitive p21Ras-ERK pathway mediates S-nitrosoglutathione-induced apoptosis

p21Ras protein plays a critical role in cellular signaling that induces either cell cycle progression or apoptosis. Nitric oxide (NO) has been consistently reported to activate p21Ras through the redox sensitive cysteine residue (118). in this study, we demonstrated that the p21Ras-ERK pathway regulates THP-1 monocyte/macrophage apoptosis induced by S-nitrosoglutathione (SNOG). This was apparent from studies in THP-1 cells expressing NO-insensitive p21Ras (p21Ras(C118S)) where the pro-apoptotic action of SNOG was almost abrogated. Three major MAP kinase pathways (ERK, JNK, and p38) that are downstream to p21Ras were investigated. It was observed that only the activation of ERK1/2 MAP kinases by SNOG in THP-1 cells was attributable to p21Ras. the inhibition of the ERK pathway by PD98059 markedly attenuated apoptosis in SNOG-treated THP-1 cells, but had a marginal effect on SNOG-treated THP-1 cells expressing NO-inserisitive p21Ras. the inhibition of the JNK and p38 pathways by selective inhibitors had no marked effects on the percentage of apoptosis. the induction of p21Waf1 expression by SNOG was observed in THP-1 cells harboring mutant and wild-type p21Ras, however in cells expressing mutant Ras, the expression of p21Waf1 was significantly attenuated. the treatment of THP-1 cells expressing wild-type p21Ras with PD98059 resulted in significant attenuation of p21Waf1 expression. These results indicate that the redox sensitive p21Ras-ERK pathway plays a critical role in sensing and delivering the pro-apoptotic signaling mediated by SNOG. (C) 2008 Elsevier Inc. All rights reserved.Universidade Federal de São Paulo, Escola Paulista Med, Ctr Interdisciplinary Terapia Genica CINTERGEN, Dept Bioquim Biol Mol, São Paulo, BrazilUniv São Paulo, Fac Ciencias Farmaceut, BR-05508 São Paulo, BrazilNYU, Dept Pharmacol, New York Sch Med, New York, NY 10016 USAUniversidade Federal de São Paulo, Escola Paulista Med, Ctr Interdisciplinary Terapia Genica CINTERGEN, Dept Bioquim Biol Mol, São Paulo, BrazilWeb of Scienc

Genetic barcode sequencing for screening altered population dynamics of hematopoietic stem cells transduced with lentivirus

Insertional mutagenesis has been associated with malignant cell transformation in gene therapy protocols, leading to discussions about vector security. Therefore, clonal analysis is important for the assessment of vector safety and its impact on patient health. Here, we report a unique approach to assess dynamic changes in clonality of lentivirus transduced cells upon Sanger sequence analysis of a specially designed genetic barcode. In our approach, changes in the electropherogram peaks are measured and compared between successive time points, revealing alteration in the cell population. After in vitro validation, barcoded lentiviral libraries carrying IL2RG or LMO2 transgenes, or empty vector were used to transduce mouse hematopoietic (ckit+) stem cells, which were subsequently transplanted in recipient mice. We found that neither the empty nor IL2RG encoding vector had an effect on cell dynamics. In sharp contrast, the LMO2 oncogene was associated with altered cell dynamics even though hematologic counts remained unchanged, suggesting that the barcode could reveal changes in cell populations not observed by the frontline clinical assay. We describe a simple and sensitive method for the analysis of clonality, which could be easily used by any laboratory for the assessment of cellular behavior upon lentiviral transduction

Study of lymphocyte subpopulations in bone marrow in a model of protein-energy malnutrition

Objective: Protein-energy malnutrition (PEM) is an important public health problem affecting millions of people worldwide. Hematopoietic tissue requires a high nutrient supply, and a reduction in leukocytes, especially lymphocytes, suggests that some nutritional deficiencies might be altering bone marrow function and decreasing its ability to produce lymphocytes. In this study, we evaluated the effect that PEM has on lymphocyte subtypes and the cell cycle of CD5(+) cells. Methods: Swiss mice were subjected to PEM using a low-protein diet containing 4% protein. When the experimental group had lost about 20% of their original body weight, we collected blood and bone marrow cells and evaluated the hemogram, the myelogram, bone marrow lymphoid markers using flow cytometry, and the cell cycle in CD5(+) bone marrow. Results: Malnourished animals presented anemia, reticulocytopenia, and leukopenia with lymphopenia. The bone marrow was hypocellular, and flow cytometric analyses of bone marrow cells showed cells that were CD45(+) (91.2%), CD2(+) (84.9%), CD5(+) (37.3%), CD3(+) (23.5%), CD19(+) (43.3%), CD22(+) (34.7%), CD19(+)/CD2(+) (51.2%), CD19(+)/CD3(+)(24.0%), CD19(+)/CD5(+) (13.2%), CD22(+)/CD2(+) (40.1%), CD22(+)/CD3(+) (30.3%), and CD22(+)/CD5(+) (1.1%) in malnourished animals and CD45(+) (97.5%), CD2(+) (42.9%), CD5(+) (91.5%), CD3(+) (92.0%), CD19(+) (52.0%), CD22(+) (75.6%), CD19(+)/CD2(+) (62.0%), CD19(+)/CD3(+) (55.4%), CD19(+)/CO5(+) (6.7%), CD22(+)/CD2(+) (70.3%), CD22(+)/CD3(+) (55.9%), and CD22(+)/ CD5(+) (8.4%) in control animals. Malnourished animals also presented more CD5(+) cells in the G0 phase of cell cycle development. Conclusion: Malnourished animals presented bone marrow hypoplasia, maturation interruption, prominent lymphopenia with depletion in the lymphoid lineage, and changes in cellular development. We suggest that these changes are some of the primary causes of lymphopenia in cases of PEM and partly explain the increase in susceptibility to infections found in malnourished individuals. Published by Elsevier Inc.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Pesquisa (CNPq), Brazi