CD59 can be found in body fluids including blood plasma, saliva, amniotic fluid, seminal fluid, and urine. It is expressed as a 18-25 kD glycoprotein (in lymphocytes)anchored in the membrane by GPI tail. Since CD59 is well known membrane-associated complement regulator protein, like CD55, and present on all blood cells, anti-CD55 and anti-CD59 appear to be the most effective Mabs to detect very minor negative cell subsets (less than 1 % on erythrocytes or less than 5 % on PMN leukocytes.Synonyms: 20 kDa homologous restriction factor, HRF-20, HRF20, MAC-IP, MAC-inhibitory protein, MACIF, MEM43 antigen, MIC11, MIN1, MIN2, MIN3, MIRL, MSK21, Membrane attack complex inhibition factor, Membrane inhibitor of reactive lysis, Protectin