Soluble CTLA-4 as a context-dependent immune checkpoint: biology, biomarker potential, and therapeutic implications
Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) exists not only as a membrane-bound immune checkpoint but also as a naturally secreted soluble isoform (sCTLA-4), generated primarily through exon 3 skipping. This review focuses specifically on spli…