MHC class I and II expression in juvenile dermatomyositis skeletal muscle.

OBJECTIVE: To assess MHC I and II expressions in muscle fibres of juvenile dermatomyositis (JDM) and compare with the expression in polymyositis (PM), dermatomyositis (DM) and dystrophy. PATIENTS AND METHODS: Forty-eight JDM patients and 17 controls (8 PM, 5 DM and 4 dystrophy) were studied. The mean age at disease onset was 7.1+/-3.0 years and the mean duration of weakness before biopsy was 9.4+/-12.9 months. Routinehistochemistry and immunohistochemistry (StreptABComplex/HRP) for MHC I and II (Dakopatts) were performed on serial frozen muscle sections in all patients. Mann-Whitney, Kruskal Wallis, chi-square and Fisher's exact statistical methods were used. RESULTS: MHC I expression was positive in 47 (97.9%) JDM cases. This expression was observed independent of time of disease, corticotherapy previous to muscle biopsy and to the grading of inflammation observed in clinical, laboratorial and histological parameters. The expression of MHC I was similar on JDM, PM and DM, and lower in dystrophy. On the other hand, MHC II expression was positive in just 28.2% of JDM cases and was correlated to histological features as inflammatory infiltrate, increased connective tissue and VAS for global degree of abnormality (p<0.05). MHC II expression was similar in DM/PM and lower in JDM and dystrophy, and it was based on the frequency of positive staining rather than to the degree of the MCH II expression. CONCLUSIONS: MHC I expression in muscle fibres is a premature and late marker of JDM patient independent to corticotherapy, and MHC II expression was lower in JDM than in PM and DM.

Sydenham chorea: clinical and laboratory findings. Analysis of 187 cases.

Sydenham's chorea (chorea minor, St. Vitus dance, rheumatic encephalitis), described by Thomas Sydenham in 1686, is considered one of the major manifestations of rheumatic fever (1, 2, 3, 4). Clinically it is characterized by involuntary movements, hypotonia, dysarthria, emotional disorders, and less frequently, by other neurological manifestations such as weakness, headache, seizures and sensory abnormalities (1,4). The motor disorders may be generalized or unilateral, in this case constituting a hemichorea (3). Chorea may present associated to other rheumatic fever manifestations during an acute episode, or in isolated form, characterizing the so-called "pure" chorea (5, 6, 7). Its etiology and pathophysiological mechanisms are still unclear, although its relation with a previous pathophysiological group A Beta-hemolytic streptococcus infection is well established (8). There is also evidence of the participation of immunological mechanisms in its pathogenesis, such as the finding of serum anti-nucleus caudatus and anti-subthalamic antibodies (9) and increase in IgG levels in cerebrospinal fluid of patients with chorea (10). In developed countries due to the reduction in rheumatic fever incidence and decrease in frequency of chorea as its manifestation (3, 11), the latter has become rare. However, in developing countries rheumatic fever remains a public health problem. In Brazil, in the last years an increase in the incidence of chorea has been observed as part of the clinical picture of rheumatic fever (12). The present study reports the clinical and laboratory findings of 187 cases of Sydenham's chorea followed-up during the period of January 1980 to December 1990 in two university centers in the city of Sao Paulo, Brazil.