Abstract 13606: Patients With Lymphocytic Myocarditis Have Increased Lymphocytes in the Skeletal Muscle: A New Diagnostic Tool
Introduction: Lymphocytic myocarditis (LM) is a disease which is mostly the result of viral infection and is notoriously difficult to diagnose. There are indications in literature that skeletal muscle functions to a certain extent as a mirror to inflammation in the heart muscle. In this study, we investigated the potential of skeletal muscle tissue as diagnostic criterium for LM.
METHODS: From 21 patients diagnosed post-mortem with LM and 9 control patients, quadriceps skeletal muscle tissue was stained immunohistochemically for CD45 (lymphocytes), CD3 (T-lymphocytes), CD4 (T-helper cells), CD8 (cytotoxic T-lymphocytes), CD20 (B-lymphocytes), CD68 (macrophages) and MPO (neutrophilic granulocytes). As a proof of concept, quadriceps skeletal muscle obtained from mice with acute coxsackievirus B3-induced myocarditis and control mice were analyzed as well. The quantity of positive-staining cells was compared between the LM group and control group.
RESULTS: A statistically significant increase in cell numbers was observed in skeletal muscle tissue of LM patients compared to control patients for the lymphocytic markers CD45, CD3 and CD8. The number of lymphocytes in the skeletal muscle tissue could diagnose LM with specificity of 100% and sensitivity of 71%. Lymphocytes were also increased in skeletal muscle tissue of mice with acute coxsackievirus B3-induced myocarditis, which coincided with the presence of viral RNA. No increase in lymphocytes was observed in skeletal muscle tissue from patients with a non-infectious form of myocarditis, and the number of lymphocytes in skeletal muscle tissue was not found to be related to the age or gender of the patients.
CONCLUSION: This study demonstrates that lymphocytes in skeletal muscle tissue have potential to be used as a new diagnostic criterium for LM.
- © 2013 by American Heart Association, Inc.