Th2細胞
PD-L2 is primarily expressed on professional antigen presenting cells including dendritic cells (DCs) and macrophages. Others have shown PD-L2 expression in certain T helper cell subsets and cytotoxic T cells. PD-L2 protein is widely expressed in many healthy tissues including the GI tract tissues, skeletal muscles, tonsils, and pancreas. Additionally, PD-L2 has moderate to high expression in triple-negative breast cancer and gastric cancer and low expression in renal cell carcinoma. PD-L2 mRNA is widely expressed and not enriched in any particular tissue.