We observed the CD4 + memory T cells, CD4 + naive T cells, CD4 + T cells, CD8 + T cells, CD8 + Tem, macrophages, macrophages M1, mast cells, monocytes, neutrophils, NK cells, Tgd cells, and Th1 cells were significantly up-regulated in the HF subgroup compared with the LF subgroup. The gene discussed is CD8A; the disease is Lassa fever.