This study reveals that Streptococcus parasanguinis and Streptococcus salivarius are enriched DLBCL patients with high NCCN-IPI score, and also show negative correlations with the proportions of peripheral immune cells (Tregs, CD38+ NREXT, NK3, HLA-DR+ NK, HLA-DR+ NKT, HLA-DR+CD94+CD159c+ NKT and CD38+EMCD8+ T cells). The gene discussed is KLRC2; the disease is diffuse large B-cell lymphoma.