VSIR and B-cell chronic lymphocytic leukemia: Additionally, it has recently been reported that Siglec-7 may interact with PSGL-1 on chronic lymphocytic leukemia B cells, which is known to be one of VISTA interaction pathways, hinting at a potential negative feedback regulatory mechanism between Siglec-7 and VISTA in the mammary microenvironment (29, 67, 68).