HHLA2 and hepatocellular carcinoma: It was found that the HHLA2-high subgroup of patients with HCC was characterized by elevated fractions of M0 macrophages, neutrophils, follicular helper T cells, memory-activated CD4+ T cells, Tregs, and dendritic cells, while there was a decrease in the fractions of M2 macrophages, monocytes, activated mast cells, and resting NK cells [31,35].