Description
CD5L (CD5 antigen-like), also known as Sp alpha and AIM, is a 50 kDa secreted glycoprotein that belongs to the SRCR (scavenger receptor cysteine rich) group B family of proteins. CD5L is up-regulated in macrophages at inflammatory sites. It sustains inflammatory reactions by both increasing the phagocytic capacity of macrophages and impeding the apoptosis of local macrophages, NK cells, and T cells. CD5L functions as a pattern recognition molecule by binding both lipoteichoic acid (LTA) on Gram positive and lipopolysaccharide (LPS) on Gram negative bacteria. In the thymic cortex, CD5L protects cortical CD4+CD8+thymocytes from apoptosis. CD5L circulates in the serum in complex with IgM.