Serum sickness proteins to form immune complexes. These complexes precipitate, enter the walls of blood vessels, and activate the complement cascade, initiating an inflammatory response and consuming much of the available complement component 3 (C3). The result is a leukocytoclastic vasculitis. This results in hypocomplementemia, a low C3 level in serum. They can also cause more reactions resulting in typical symptoms of serum sickness. Serum sickness can be developed as a result of exposure to antibodies derived from animals. These sera or antitoxins are generally administered to prevent or treat an infection or envenomation. Some of the drugs associated with serum sickness
P-selectin glycoprotein ligand-1 is a glycoprotein found on white blood cells and endothelial cells that binds to P-selectin (P stands for platelet), which is one of a family of selectins that includes E-selectin (endothelial) and L-selectin (leukocyte). Selectins are part of the broader family of cell adhesion molecules. PSGL-1 can bind to all three members of the family but binds best (with the highest affinity) to P-selectin. PSGL-1 protein requires two distinct posttranslational modifications to gain its selectin binding activity: PSGL-1 is expressed on all white blood cells and plays an important role in the recruitment of white blood cells into inflamed tissue: