Serum (blood) Serum (blood) In blood, the serum () is the component that is neither a blood cell (serum does not contain white blood cells- leukocytes, or red blood cells- erythrocytes), nor a clotting factor; it is the blood plasma not including the fibrinogens. Serum includes all proteins not used in blood clotting and all the electrolytes, antibodies, antigens, hormones, and any exogenous substances (e.g., drugs and microorganisms). The study of serum is serology. Serum is used in numerous diagnostic tests, as well as blood typing. Measurements of serum concentrations has proved useful in many fields including clinical trials of therapeutic vs
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: