Specifically, the immune cell infiltration results indicated that a significant number of plasma cells, neutrophils, immature B cells, and immature CD4 T cells infiltrated in the periodontitis group (Fig. 6A), whereas a large number of CD8 T cells, follicular helper T cells, resting dendritic cells, and resting mast cells infiltrating in the healthy group (Fig. 6B). The gene discussed is CD8A; the disease is periodontitis.