C2 and hepatocellular carcinoma: In the TCGA cohort, significantly higher proportions of resting CD4 memory T cells and macrophage M1 cells were found in HCC patients with higher C2 expression, while significantly higher proportions of macrophage M0 cells, activated CD4 memory cells, and plasma cells were found at HCC patients with lower C2 expression (all p < 0.05, Figure 4(a)).