T cell activation appears to play a key role also in initiating lung damage in both PM and DM-associated ILD, demonstrated by a predominance of T lymphocytes in bronchoalveolar lavage with a decreased CD4+/CD8+ ratio [30] and high inflammatory cytokine expression in ILD-IIM, in particular TNF alpha in ILD+ PM and DM. This evidence concerns the gene CD4 and dermatomyositis.