Characteristics and prognostic implications of peripheral blood lymphocyte subsets in patients with anti-MDA5 antibody positive dermatomyositis-interstitial lung disease

Objectives To examine the characteristics of blood lymphocyte subsets in dermatomyositis-interstitial lung disease (DM-ILD) inflicted patients with positive anti-melanoma differentiation-associated gene 5 (anti-MDA5), as well as its prognosis value in this set of patients.Methods Data were retrospectively collected from 253 DM-ILD patients from three hospitals in China between January 2016 to January 2021. Patients were grouped into anti-MDA5 antibody positive group (MDA5(+) DM-ILD) and anti-MDA5 antibody negative group (MDA5(-) DM-ILD) based on myositis-specific autoantibody test results. Demographic characteristics, lymphocyte subsets patterns and other clinical features were compared between the two groups. The association of lymphocyte subsets with 180-day mortality was investigated using survival analysis in MDA5(+) DM-ILD.Results Out of 253 eligible patients with DM-ILD, 59 patients were anti-MDA5(+) and 194 were anti-MDA5(-). Peripheral blood lymphocyte count, CD3(+) count, percentage of CD3(+), CD3(+)CD4(+) count, and CD3(+)CD8(+) count was lower in MDA5(+) DM-ILD than in MDA5(-) DM-ILD- (all P < 0.001) as well as CD3(-)CD19(+) count (P = 0.04). In MDA5(+) DM-ILD, CD3(+)CD8(+) count <= 49.22 cell/mu L (HR = 3.81, 95%CI [1.20,12.14]) and CD3-CD19(+) count <= 137.64 cell/mu L (HR = 3.43, 95%CI [1.15,10.24]) were independent predictors of mortality. CD3(+)CD8(+) count <= 31.38 cell/mu L was associated with a higher mortality risk in all DM-ILD patients (HR = 8.6, 95%CI [2.12,31.44]) after adjusting for anti-MDA5 and other clinical characteristics.Conclusion Significant lymphocytes decrease was observed in MDA5(+) DM-ILD patients. CD3(+)CD8(+) cell count was associated with worse prognosis in both MDA5(+) DM-ILD and all DM-ILD patients.