Adenosine deaminase (ADA; EC 3.5.4.4) catalyzes the irreversible deamination of adenosine and 2′-deoxyadenosine to inosine and 2′-deoxyinosine, respectively. Adenosine deaminase is implicated in purine metabolism and distributed in most mammalian tissues. Genetic Adenosine deaminase deficiency results in lymphopenia and severe combined immunodeficiency disease by decreasing the differentiation and maturation of lymphoid cells. Adenosine deaminase is a signaling molecule related to the activation of T lympho-cytes, making it a useful inflammation marker, especially for menin-gitis and tuberculous pleuritis.