PCIF1 expression had a positive correlation with CD4+ T-cell infiltration in kidney renal clear cell carcinoma (KIRC), CD8+ T cells, macrophages, and B cells in thyroid carcinoma (THCA), and immune checkpoint genes (ICGs) in LIHC but a negative correlation with CD4+ T cells, neutrophils, myeloid dendritic cells, and ICGs in THCA. Here, CD4 is linked to thyroid gland carcinoma.