We compared the fractions of 22 immunocytes between healthy and periodontitis, and 13 immunocytes were altered in periodontitis tissue including 5 increasing immunocytes fractions (plasma cell, neutrophils, T cells CD4 memory activated, dendritic cells activated and NK cells resting) and 8 decreasing immunocytes fractions (Tregs, dendritic cells resting, eosinophils, mast cells resting, macrophages M1, B cells memory, T cells follicular helper and T cells CD4 memory resting) in periodontitis tissue (Fig. 1b, Additional file 1: Table S1). The gene discussed is CD4; the disease is periodontitis.