The characteristics of lymphocytes in patients positive for anti-MDA5 antibodies in interstitial lung disease.

OBJECTIVE The aim was to investigate the characteristics of blood lymphocytes in patients positive for anti-melanoma differentiation-associated gene 5 antibodies (anti-MDA5+) in interstitial lung disease. METHODS Thirty-eight anti-MDA5+ patients with interstitial lung disease were admitted to our hospital, and the lymphocyte count, lymphocyte subtypes and lung high-resolution CT were recorded. Some of the cases were examined by bone marrow aspiration. RESULTS Compared with the control group, the blood lymphocyte counts of anti-MDA5+ patients before treatment were significantly lower (P < 0.05). After treatment, lung interstitial lesions in some cases were reduced and the lymphocyte counts increased, whereas their CD4:CD8 ratio decreased (P < 0.05). In contrast, lung interstitial lesions of other cases were exacerbated after treatment and the lymphocyte counts decreased, whereas the CD4:CD8 ratio increased (P < 0.05). In cases with exacerbated lung interstitial lesions after treatment, there were fewer CD4 and CD8 T cells than before treatment, and the change in CD8 T cells was significant (P < 0.05). Bone marrow aspiration biopsy indicated that there was no abnormality in the distribution of bone marrow lymphocytes. CONCLUSION Anti-MDA5+ patients showed a decrease in blood lymphocyte counts. The presence of anti-MDA5+ in patients with pulmonary interstitial lesions was positively correlated with blood lymphocyte counts but negatively correlated with the CD4:CD8 ratio. The CD8 T cells decreased more significantly than CD4 T cells in patients with aggravation of interstitial lung disease. The change in blood lymphocytes in anti-MDA5+ patients might be attributable to transfer of lymphocytes to the lungs to participate in the local immune response.