Description
Adenosine Deaminase (ADA, adenosine aminohydrolase) is one of the key enzymes of purine nucleotide catabolism. It catalyses the hydrolytic deamination of adenosine and deoxy?adenosine to inosine and deoxyinosine. ADA is expressed in virtually all tissues and is expressed at high levels in T-lymphocytes. Adenosine Deaminase deficiency can cause a form of SCID (severe combined immunodeficiency) and lymphopenia in both B- and T-cell lineages (3, 4). ADA can be used as a sensitive test marker for tuberculous pleuritis (5). Although it is primarily a cytosolic enzyme, ADA is known to be a positive regulator of T-cell co?activation due to its binding to CD26 at the cell surface. The interaction of ADA with CD26 regulates lymphocyte-epithelial cell adhesion