Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


MHC Classes I and II Expressions in Membrane and Cytoplasm of Muscle Fibers in Untreated Juvenile and Adult Dermatomyositis.

Maluf Elias Sallum,  Adriana, Katsuyuki Shinjo,  Samuel, Souza Carvalho,  Mary, Artur Almeida da Silva,  Clóvis, Levy-Neto,  Maurício, Kazue Nagahashi Marie,  Suely

Background:

Recently, we have shown that MHC I expression in muscle fibers is a premature and late marker of treated and untreated juvenile dermatomyositis (JDM). However this alteration was not systematically studied in adult DM (ADM). Moreover, simultaneous assessment of MHC I and II expressions in fibers membrane and cytoplasm in both untreated diseases has not been performed.

Objectives:

To assess the MHC I and II expressions in fibers membrane and cytoplasm in untreated ADM and JDM and to correlate to clinical, laboratorial, and treatment outcome features.

Patients and Methods:

Twenty-seven ADM and 34 JDM patients, fulfilling Bohan and Peter criteria diagnosed from 1990 to 2010, were included in this study. Routine histochemistry and immunohistochemistry (StreptABComplex/HRP) for MHC I and II (Dakopatts) were performed on serial frozen muscle sections. Each biopsy specimen was coded and analyzed concomitantly by two investigators (AMES and SKS). The pathology readers were blinded to diagnosis, clinical status and therapy when the biopsies were evaluated. Expressions of MHC I and II were assessed as negative or positive stained fibers.

Results:

The mean age at disease onset was significantly higher in ADM than in JDM (42.7±18.3 vs. 8.2±3.8 years, p<0.001), whereas the symptoms duration before muscle biopsy were similar in both groups (9.8±13.3 vs. 7.1±10.7 months; p=0.388). No statistical differences were observed regarding gender, ethnicity, frequency of constitutional symptoms, disease severity, organ involvement (articular, pulmonary, cardiac or gastrointestinal), comorbidities, laboratorial (CK and aldolase levels) and treatment (prednisone, intravenous methylprednisolone and immunosuppressive drugs) (p=0.050), except for the lower frequency of Gottron signal in ADM compared to JDM patients (85.2 vs. 100.0%, p=0.034). Regarding the immunohistochemical analysis, the frequency of MHC I expression in fibers membrane (85.2 vs. 100.0%, p=0.034) and cytoplasm (74.1 vs. 97.1%, p=0.017) was significantly lower in ADM than JDM. In contrast, the MHC II expressions in fibers membrane (70.4 vs. 35.3%; p=0.010) and the cytoplasm (44.5% vs. 17.7%, p=0.028) were higher in ADM than JDM. Additionally, the MHC I and II expressions were not correlated to demographic data, clinical and laboratorial features, including CK levels and disease duration before muscle biopsy.

Conclusions:

The MHC I and II expressions differ in muscle fiber in JDM and ADM. These diagnostic tools can be routinely used independent of period of time until muscle biopsy.

To cite this abstract, please use the following information:
Maluf Elias Sallum, Adriana, Katsuyuki Shinjo, Samuel, Souza Carvalho, Mary, Artur Almeida da Silva, Clóvis, Levy-Neto, Maurício, Kazue Nagahashi Marie, Suely; MHC Classes I and II Expressions in Membrane and Cytoplasm of Muscle Fibers in Untreated Juvenile and Adult Dermatomyositis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :927
DOI: 10.1002/art.28695

Abstract Supplement

Meeting Menu

2010 ACR/ARHP