Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

OBJECTIVE: To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis. METHOD: In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter's criteria) and a control group consisting of four dystrophic and five Pompe's disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X). RESULTS: The mean ages at disease onset were 42.0±15.9 and 7.3±3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (

Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

OBJECTIVE: To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis. METHOD: In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter's criteria) and a control group consisting of four dystrophic and five Pompe's disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X). RESULTS: The mean ages at disease onset were 42.0 +/- 15.9 and 7.3 +/- 3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (p<0.050). Moreover, a significantly higher frequency of major histocompatibility complex I (96.4% vs. 50.0%, p<0.001) compared with major histocompatibility complex II expression (14.3% vs. 53.6%, p = 0.004) was observed in juvenile dermatomyositis. Fiber damage (p = 0.006) and increased connective tissue (p<0.001) were significantly higher in adult dermatomyositis compared with the presence of perifascicular atrophy (p<0.001). The results of the histochemical and histological data did not correlate with the demographic data or with the clinical and laboratory features. CONCLUSION: The overexpression of major histocompatibility complex I was an important finding for the diagnosis of both groups, particularly for juvenile dermatomyositis, whereas there was lower levels of expression of major histocompatibility complex II than major histocompatibility complex I. This finding was particularly apparent in juvenile dermatomyositis.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPQ [300248/2008-3]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Federico FoundationFederico Foundatio

Redução na força muscular e capacidade funcional em pacientes fisicamente inativos com lúpus eritematoso sistêmico de início juvenil, apesar de doença muito leve

ResumoObjetivoComparar a força muscular (ou seja, a força muscular dos membros superiores e inferiores) e a capacidade funcional de pacientes fisicamente inativos com lúpus eritematoso sistêmico de início juvenil (LESJ) com controles saudáveis (CTRL).MétodosEstudo transversal cuja amostra foi composta por 19 pacientes com LESJ (entre 9 e 18 anos) e 15 CTRL pareados por idade, sexo, índice de massa corporal (IMC) e nível de atividade física (avaliada através do uso de acelerômetros). A força dos membros superiores e inferiores foi avaliada pelo teste de uma repetição máxima (1‐RM). A força isométrica foi avaliada através do uso de um dinamômetro. A capacidade funcional foi avaliada pelo Timed‐stands test (TST) e Timed‐up‐and‐go test (TUG).ResultadosQuando comparados com os CTRL, os pacientes com LESJ apresentaram menor força em 1‐RM no Leg press e supino (p=0,026 e p=0,008, respectivamente) e uma tendência a menor força de preensão manual (p=0,052). Os pacientes com LESJ apresentaram menores escores no TST (p=0,036) e uma tendência a maior pontuação no TUG (p=0,070), quando comparados com o grupo CTRL.ConclusãoPacientes com LESJ, fisicamente inativos, com doença muito leve mostraram redução na força muscular e capacidade funcional quando comparados com controles saudáveis pareados por níveis de atividade física. Esses achados sugerem que pacientes com LESJ podem apresentar mais efeitos deletérios por manter um estilo de vida fisicamente inativo do que controles saudáveis. Além disso, alguns efeitos “residuais” subclínicos da doença ou do tratamento farmacológico parecem afetar pacientes com LESJ, mesmo com uma doença bem controlada.AbstractObjectiveTo compare muscle strength (i.e. lower‐ and upper‐body strength) and function between physically inactive childhood‐onset systemic lupus erythematosus patients (C‐SLE) and healthy controls (CTRL).MethodsThis was a cross‐sectional study and the sample consisted of 19 C‐SLE (age between 9 to 18 years) and 15 CTRL matched by age, sex, body mass index (BMI), and physical activity levels (assessed by accelerometry). Lower‐ and upper‐body strength was assess by the one‐repetition‐maximum (1‐RM) test. Isometric strength was assessed through a handgrip dynamometer. Muscle function was evaluated by the timed‐stands test (TST) and the timed‐up‐and‐go test (TUG).ResultsWhen compared with CTRL, C‐SLE showed lower leg‐press and bench‐press 1‐RM (p=0.026 and p=0.008, respectively), and a tendency towards lower handgrip strength (p=0.052). C‐SLE showed lower TST scores (p=0.036) and a tendency towards higher TUG scores (p=0.070) when compared with CTRL.ConclusionPhysically inactive C‐SLE patients with very mild disease showed reduced muscle strength and functionality when compared with healthy controls matched by physical activity levels. These findings suggest C‐SLE patients may greatly suffer from a physically inactive lifestyle than healthy controls do. Moreover, some sub‐clinical “residual” effect of the disease or its pharmacological treatment seems to affect C‐SLE patients even with a well‐controlled disease

Reproductive health aspects in men with idiopathic inflammatory myopathy: a multicenter study

OBJECTIVE: To evaluate reproductive health of males with idiopathic inflammatory myopathies (IIM), and comparing them with a control group. METHODS: Demographic data, urologic evaluation (including pubertal parameters and sexual/erectile function), testicular ultrasound, hormone profile, semen analysis, clinical features, and treatment of 25 IIM patients were evaluated. The control group was composed of 25 healthy males. RESULTS: Median age of IIM patients was similar to that of the control group (24 versus 27 years, P = 0.566). The frequency of sexual activity, number of partners with spontaneous pregnancies after the onset of the disease, and use of condom were significantly lower in IIM patients than in the control group (60% versus 96%, P = 0.004; 16% versus 60%, P = 0.0031; 40% versus 76%, P = 0.021, respectively). Moreover, the frequency of testicular atrophy (28% versus 4%, P = 0.049), elevated levels of FSH and/or LH (25% versus 0%, P = 0.05), and sperm abnormalities (40% versus 0%, P = 0.0006) were statistically higher in IIM patients than in the control group. Median age of onset of IIM and current age were significantly higher in IIM patients with sexual/erectile dysfunction than in patients without this dysfunction (41 versus 12.5 years, P = 0.014; 46 versus 21 years, P = 0.027, respectively). On the other hand, differences in the age of spermarche, parameters of gonadal function, disease activity, muscle enzymes, and treatment were not observed between IIM patients with or without sexual/erectile dysfunction. CONCLUSION: This is the first study to identify changes in reproductive health and gonadal dysfunction in male IIM patients. Rheumatologists should discuss sexual problems with their patients, counseling them on contraceptive methods.OBJETIVO: Avaliar a saúde reprodutiva de homens com miopatia inflamatória idiopática (MII) e compará-la com controles saudáveis. MÉTODOS: Vinte e cinco pacientes com MII (dermatomiosite ou polimiosite) foram avaliados com relação aos dados demográficos, exame urológico (incluindo parâmetros pubertários e função sexual/erétil), ultrassonografia testicular, perfil hormonal, análise seminal, características clínicas e tratamento. O grupo controle incluiu 25 homens saudáveis. RESULTADOS: A mediana da idade atual foi similar nos pacientes com MII e controles (24 versus 27 anos, P = 0,566). As frequências de atividade sexual, número de parceiras com gestações espontâneas após início da doença e uso de preservativo masculino foram significativamente menores nos pacientes com MII versus controles (60% versus 96%, P = 0,004; 16% versus 60%, P = 0,0031; 40% versus 76%, P = 0,021; respectivamente). Além disso, as frequências de atrofia testicular (28% versus 4%, P = 0,049), níveis elevados de FSH e/ou LH (25% versus 0%, P = 0,05) e alterações dos espermatozoides (40% versus 0%, P = 0,0006) foram estatisticamente maiores nos pacientes com MII quando comparados aos controles. As medianas das idades de início da doença e atual foram estatisticamente maiores nos pacientes com MII que apresentaram disfunção sexual/erétil versus sem disfunção (41 versus 12,5 anos, P = 0,014; 46 versus 21 anos, P = 0,027; respectivamente). Entretanto, comparando-se, pacientes com disfunção sexual/erétil e sem disfunção, nenhuma diferença foi evidenciada em relação à idade da espermarca, parâmetros de função gonadal, atividade da doença, enzimas musculares e tratamento. CONCLUSÃO: Este foi o primeiro estudo que identificou alterações da saúde reprodutiva e disfunção gonadal em homens com MII. Reumatologistas devem discutir problemas sexuais e orientar contracepção aos seus pacientes.FMUSP Departamento de PediatriaFaculdade de Medicina da Universidade de São Paulo Hospital das Clínicas Instituto da CriançaUniversidade Federal do Pará Departamento de PediatriaFMUSP HC ICrFMUSP HCUNIFESP Departamento de PediatriaUNIFESP Setor de Reumatologia PediátricaSanta Casa de São Paulo Setor de Reumatologia PediátricaFMUSP HC Departamento de RadiologiaUNIFESP, Depto. de PediatriaUNIFESP, Setor de Reumatologia PediátricaSciEL

Chronic spontaneous urticaria: a survey of 852 cases of childhood-onset systemic Lupus Erythematosus

Data regarding the prevalence of chronic spontaneous urticaria (CSU) in childhood-onset systemic lupus erythematosus (cSLE) patients and possible associated factors are limited to a few case reports. The objectives of this study were to assess CSU in a large cSLE population, in order to evaluate the demographic data, clinical manifestations, disease activity/damage, laboratory abnormalities and treatment. A retrospective multicenter cohort study (Brazilian cSLE group) was performed in 10 Pediatric Rheumatology services and included 852 cSLE patients. CSU was diagnosed according to the guidelines of the European Academy of Allergy and Clinical Immunology, the Global Allergy and Asthma European Network, the European Dermatology Forum and the World Allergy Organization. Patients with CSU (evaluated at urticaria diagnosis) and patients without CSU (evaluated at the last visit) were assessed for lupus clinical/laboratory features and treatment. CSU was observed in 10/852 cSLE patients (1.17%). The median of cSLE duration at urticaria diagnosis was 0 (-3 to 5) years. Comparison of cSLE patients with and without CSU revealed a greater frequency of constitutional symptoms (40 vs. 8%, p = 0.006), reticuloendothelial system involvement (30 vs. 3%, p = 0.003), mucocutaneous (90 vs. 28%, p < 0.0001) and musculoskeletal manifestations (50 vs. 6%, p < 0.0001) and methylprednisolone pulse therapy use (60 vs. 9%, p < 0.0001) in the former group. The frequency of immunosuppressive treatment was lower in patients with CSU (p = 0.018). The median SLE Disease Activity Index 2000 (12 vs. 2, p < 0.0001) and erythrocyte sedimentation rate (40 vs. 19 mm/1st hour, p = 0.024), was higher in patients with CSU. To our knowledge, this is the first study with evidence that CSU may be linked to cSLE. We also demonstrated that this particular skin manifestation occurs predominantly at disease onset and is associated with lupus moderate/high disease activity without major organ involvement1673186192CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ301805/2013-0; 2009/51897-5; 302724/2011-

Profile of paediatric rheumatology specialists and services in the state of São Paulo

INTRODUCTION: Paediatric rheumatology (PR) is an emerging specialty, practised by a limited number of specialists. Currently, there is neither a record of the profile of rheumatology patients being treated in Brazil nor data on the training of qualified rheumatology professionals in the country. OBJECTIVE: To investigate the profile of PR specialists and services, as well as the characteristics of paediatric patients with rheumatic diseases, for estimating the current state of rheumatology in the state of São Paulo. PATIENTS AND METHODS: In 2010, the scientific department of PR of the Paediatric Society of São Paulo administered a questionnaire that was answered by 24/31 accredited specialists in PR practising in state of São Paulo and by 8/21 institutions that provide PR care. RESULTS: Most (91%) of the surveyed professionals practise in public institutions. Private clinics (28.6%) and public institutions (37.5%) reported not having access to nailfold capillaroscopy, and 50% of the private clinics reported not having access to acupuncture. The average duration of professional practise in PR was 9.4 years, and 67% of the physicians had attended postgraduate programmes. Seven (87.5%) public institutions perform teaching activities, in which new paediatric rheumatologists are trained, and five (62.5%) offer postgraduate programmes. Two-thirds of the surveyed specialists use immunosuppressants and biological agents classified as restricted use by the Health Secretariat. The disease most frequently reported was juvenile idiopathic arthritis (29.1-34.5%), followed by juvenile systemic lupus erythematosus (JSLE) (11.6-12.3%) and rheumatic fever (9.1-15.9%). The incidence of vasculitis (including Henoch-Schönlein purpura, Wegener's granulomatosis, and Takayasu's arteritis) and autoinflammatory syndromes was higher in public institutions compared to other institutions (P = 0.03, P = 0.04, P = 0.002, and P < 0.0001, respectively). Patients with JSLE had the highest mortality rate (68% of deaths), mainly due to infection. CONCLUSION: The field of PR in the state of São Paulo has a significant number of specialists with postgraduate degrees who mostly practise at teaching institutions with infrastructures appropriate for the care of high-complexity patients.INTRODUÇÃO: A reumatologia pediátrica (RP) é uma especialidade emergente, com número restrito de especialistas, e ainda não conta com uma casuística brasileira sobre o perfil dos pacientes atendidos e as informações sobre a formação de profissionais capacitados. OBJETIVO: Estudar o perfil dos especialistas e dos serviços em RP e as características dos pacientes com doenças reumáticas nessa faixa etária a fim de estimar a situação atual no estado de São Paulo (ESP). PACIENTES E MÉTODOS: No ano de 2010 o departamento científico de RP da Sociedade de Pediatria de São Paulo encaminhou um questionário respondido por 24/31 especialistas com título de especialização em RP que atuam no ESP e por 8/12 instituições com atendimento nesta especialidade. RESULTADOS: A maioria (91%) dos profissionais exerce suas atividades em instituições públicas. Clínicas privadas (28,6%) e instituições (37,5%) relataram não ter acesso ao exame de capilaroscopia e 50% das clínicas privadas não tem acesso à acupuntura. A média de tempo de prática profissional na especialidade foi de 9,4 anos, sendo 67% deles pós-graduados. Sete (87,5%) instituições públicas atuam na área de ensino, formando novos reumatologistas pediátricos. Cinco (62,5%) delas têm pós-graduação. Dois terços dos especialistas utilizam imunossupressores e agentes biológicos de uso restrito pela Secretaria da Saúde. A doença mais atendida foi artrite idiopática juvenil (29,1%-34,5%), seguida de lúpus eritematoso sistêmico juvenil (LESJ) (11,6%-12,3%) e febre reumática (9,1%-15,9%). Vasculites (púrpura de Henoch Schönlein, Wegener, Takayasu) e síndromes autoinflamatórias foram mais incidentes nas instituições públicas (P = 0,03; P = 0,04; P = 0,002 e P < 0,0001, respectivamente). O LESJ foi a doença com maior mortalidade (68% dos óbitos), principalmente por infecção. CONCLUSÃO: A RP no ESP conta com um número expressivo de especialistas pós-graduados, que atuam especialmente em instituições de ensino, com infraestrutura adequada ao atendimento de pacientes de alta complexidade.Universidade Federal de São Paulo (UNIFESP) Departamento de Pediatria Setor de Reumatologia PediátricaUniversidade de São Paulo Faculdade de Medicina Hospital das ClínicasSanta Casa de Misericórdia de São Paulo Departamento de Pediatria Setor de ReumatologiaUniversidade Estadual de Campinas Unidade de Reumatologia PediátricaUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Departamento de Puericultura e PediatriaSanta Casa de Misericórdia de Santos Setor de Reumatologia PediátricaFaculdade de Medicina de Botucatu Hospital Estadual de Bauru Serviço de Reumatologia PediátricaFaculdade de Medicina de BotucatuUNIFESP, Depto. de Pediatria Setor de Reumatologia PediátricaSciEL

Correlations of the expression of MHC-I and II, C5b-9 and inflammatory cells phenotyping in juvenile dermatomyositis (JDM)

A presença de uma inflamação crônica no músculo, a associação com outras doenças e a presença de auto-anticorpos, sugere o envolvimento de um mecanismo autoimune na patogênese da DMJ. Trinta e sete fragmentos musculares de pacientes com o diagnóstico de DMJ foram estudados com o objetivo de avaliar a expressão de MHC classes I e II, C5b-9 e fenotipagem das células inflamatórias CD4, CD8, CD20 e CD68 em tecido muscular e correlacionar com os principais parâmetros clínicos, laboratoriais, histológicos e terapêuticos desta doença. Os achados foram comparados à expressão em oito fragmentos musculares de pacientes com polimiosite (PM), cinco de dermatomiosite (DM) e quatro de distrofia. As expressões de MHC-I, MHC-II e C5b-9 foram identificadas por imunohistoquímica, através da técnica de imunoperoxidase StreptABComplex/HRP; as células CD20 e CD68, pelo sistema LSAB+ e CD4 e CD8, pela técnica EnVision-AP. A expressão de MHC-I apresentou positividade em 97,2% dos casos, enquanto que a expressão de MHC-II foi observada em apenas 21,6% dos casos. C5b-9 (83,8% de positividade), correlacionou-se com a presença de calcinose e envolvimento cardíaco. A presença de linfócitos CD4 (81,1% de positividade), CD8 (86,5% de positividade) e CD20 (62,2 % de positividade), e CD68 (97,2% de positividade) correlacionaram-se com o grau de inflamação observada na histologia muscular. A presença de CD4 e CD68, e marcação de C5b-9 também se correlacionaram com a intensidade de fraqueza muscular, e laboratorialmente, CD4 correlacionou-se com níveis elevados de CK e CD20 com DHL. Na DMJ observou-se maior expressão de C5b-9, CD4 e CD8 e menor expressão de MHC-I e II em comparação à DM e PM. A expressão destes marcadores foi sempre menor na distrofia. A expressão de MHC-I, adjuvante ao envolvimento dos linfócitos CD4 e CD8, sugere um mecanismo inicial celular citotóxico relacionado a maior gravidade do envolvimento muscular. A concomitância da maior expressão de C5b-9 foi um fator preditivo de comprometimento sistêmico e demanda de terapêutica imunossupresssora. Os resultados deste estudo apontam para o papel do MHC-I e II, C5b-9, CD4, CD8, CD20 e CD68 na patogênese da DMJThe presence of chronic muscle inflammation, in association with other diseases and seric autoantibodies in JDM patients, suggest the involvement of an autoimmune mechanism in the pathogenesis of this inflammatory myopathy. Thirty seven muscle biopsy specimens from patients with JDM were analyzed in order to assess the expression of MHC-I and II, C5b-9, CD4, CD8, CD20 and CD68 and to correlate with the clinical, laboratorial, histological and therapeutical parameters. These findings were compared to the expression in five dermatomyositis (DM), eight polymyositis (PM) and four dystrophy cases. Immunohistochemical reactions for MHC-I and II and C5b-9 (StreptABCcomplex/HRP), CD4, CD8 (EnVision-AP) and CD20, CD68 (LSAB+) were evaluated. MHC-I expression was positive in 97.2% of the cases, whilst MHC-II was positive in only 21.6% of the cases. C5b-9 expression (positivity of 83.8%) correlated with calcinosis and cardiac involvement. The presence of lymphocytes CD4 (positivity of 81.1%), CD8 (positivity of 86.5%), CD20 (positivity of 62.2%), and CD68 (positivity of 97.2%) correlated with inflammation in muscular histology. The presence of CD4 and CD8 and expression of C5b-9 also correlated with the severity of muscle weakness, and CD4 expression correlated with serum levels of CK and CD20 with LDH. In JDM, the expressions of C5b-9, CD4 and CD8 were statistically more significant when compared to PM and DM, while expressions of MHC-I and II were lower in JDM. All expressions were lower in dystrophy. MHC-I expression, adjuvant to the presence of CD4 and CD8 lymphocytes, corroborates the involvement of the cytotoxic cellular mechanism of muscular lesion in JDM, which correlates to severity. Concomitantly, C5b-9 expression was a predictive factor of systemic involvement and of the need for imunossupressive treatment. The results of this study indicate for the function of MHC-I and II, C5b-9, CD4, CD8, CD20 e CD68 at JDM pathogenesi

Correlations of the expression of MHC-I and II, C5b-9 and inflammatory cells phenotyping in juvenile dermatomyositis (JDM)

A presença de uma inflamação crônica no músculo, a associação com outras doenças e a presença de auto-anticorpos, sugere o envolvimento de um mecanismo autoimune na patogênese da DMJ. Trinta e sete fragmentos musculares de pacientes com o diagnóstico de DMJ foram estudados com o objetivo de avaliar a expressão de MHC classes I e II, C5b-9 e fenotipagem das células inflamatórias CD4, CD8, CD20 e CD68 em tecido muscular e correlacionar com os principais parâmetros clínicos, laboratoriais, histológicos e terapêuticos desta doença. Os achados foram comparados à expressão em oito fragmentos musculares de pacientes com polimiosite (PM), cinco de dermatomiosite (DM) e quatro de distrofia. As expressões de MHC-I, MHC-II e C5b-9 foram identificadas por imunohistoquímica, através da técnica de imunoperoxidase StreptABComplex/HRP; as células CD20 e CD68, pelo sistema LSAB+ e CD4 e CD8, pela técnica EnVision-AP. A expressão de MHC-I apresentou positividade em 97,2% dos casos, enquanto que a expressão de MHC-II foi observada em apenas 21,6% dos casos. C5b-9 (83,8% de positividade), correlacionou-se com a presença de calcinose e envolvimento cardíaco. A presença de linfócitos CD4 (81,1% de positividade), CD8 (86,5% de positividade) e CD20 (62,2 % de positividade), e CD68 (97,2% de positividade) correlacionaram-se com o grau de inflamação observada na histologia muscular. A presença de CD4 e CD68, e marcação de C5b-9 também se correlacionaram com a intensidade de fraqueza muscular, e laboratorialmente, CD4 correlacionou-se com níveis elevados de CK e CD20 com DHL. Na DMJ observou-se maior expressão de C5b-9, CD4 e CD8 e menor expressão de MHC-I e II em comparação à DM e PM. A expressão destes marcadores foi sempre menor na distrofia. A expressão de MHC-I, adjuvante ao envolvimento dos linfócitos CD4 e CD8, sugere um mecanismo inicial celular citotóxico relacionado a maior gravidade do envolvimento muscular. A concomitância da maior expressão de C5b-9 foi um fator preditivo de comprometimento sistêmico e demanda de terapêutica imunossupresssora. Os resultados deste estudo apontam para o papel do MHC-I e II, C5b-9, CD4, CD8, CD20 e CD68 na patogênese da DMJThe presence of chronic muscle inflammation, in association with other diseases and seric autoantibodies in JDM patients, suggest the involvement of an autoimmune mechanism in the pathogenesis of this inflammatory myopathy. Thirty seven muscle biopsy specimens from patients with JDM were analyzed in order to assess the expression of MHC-I and II, C5b-9, CD4, CD8, CD20 and CD68 and to correlate with the clinical, laboratorial, histological and therapeutical parameters. These findings were compared to the expression in five dermatomyositis (DM), eight polymyositis (PM) and four dystrophy cases. Immunohistochemical reactions for MHC-I and II and C5b-9 (StreptABCcomplex/HRP), CD4, CD8 (EnVision-AP) and CD20, CD68 (LSAB+) were evaluated. MHC-I expression was positive in 97.2% of the cases, whilst MHC-II was positive in only 21.6% of the cases. C5b-9 expression (positivity of 83.8%) correlated with calcinosis and cardiac involvement. The presence of lymphocytes CD4 (positivity of 81.1%), CD8 (positivity of 86.5%), CD20 (positivity of 62.2%), and CD68 (positivity of 97.2%) correlated with inflammation in muscular histology. The presence of CD4 and CD8 and expression of C5b-9 also correlated with the severity of muscle weakness, and CD4 expression correlated with serum levels of CK and CD20 with LDH. In JDM, the expressions of C5b-9, CD4 and CD8 were statistically more significant when compared to PM and DM, while expressions of MHC-I and II were lower in JDM. All expressions were lower in dystrophy. MHC-I expression, adjuvant to the presence of CD4 and CD8 lymphocytes, corroborates the involvement of the cytotoxic cellular mechanism of muscular lesion in JDM, which correlates to severity. Concomitantly, C5b-9 expression was a predictive factor of systemic involvement and of the need for imunossupressive treatment. The results of this study indicate for the function of MHC-I and II, C5b-9, CD4, CD8, CD20 e CD68 at JDM pathogenesi