CD8A and dermatomyositis: CD8+ T cells were predominant cell type infiltrating non-necrotic muscle fibres in PM [152] and are present in endomysial, perivascular and perimysial sites in PM in greater number than CD4+ T cells. [156] Positive gradient for % of CD8+ T cells in DM and PM between perivascular and endomysial sites. Increased % of CD8+ T cells and % activated T cells in endomysium in PM vs. DM [152].