CD4 and neoplasm: Using the Tumor Immune Estimation Resource (TIMER) database, we found a similar trend that a decreased HLA-DPA1 expression in LUAD was associated with reductions in immune cell populations, including B cells (r = 0.547), CD8+ T cells (r = 0.444), CD4+ T cells (r = 0.437), macrophages (r = 0.448), dendritic cells (r = 0.783), and neutrophils (r = 0.516) (Figure 11).