Reference values for plasma dipeptidyl-peptidase IV activity and iheir association with other laboratory parameters

In blood, the exopeptidase dipeptidyl-peptidase IV (DPPIV; EC 3.4.14.5) is predominantly present in a soluble form in plasma/serum and as an activatio n antigen on the membrane of lymphocytes (CD26). It modifies some important biologically active peptides (neuropeptides, chemokines), and a regulatory role for DPPlV/CD26 in immune and endocrine processes has been demonstrate d. The aim of this study was to determine reference values for plasma/serum DP PIV activity and to study the association of this activity with a series of biochemical and hematological parameters and baseline characteristics such as age, gender, blood pressure and body mass index. We studied 481 healthy subjects aged between 19 and 61 years. The group consisted of 213 men and 268 women equally divided between the different categories of age. Among th e women, 127 were taking hormone therapy (contraception/hormone replacement ) and 141 were not. A multiple regression model shows that DPPIV activity decreases significant ly with age. The activity in women is slightly lower than in men. We observ ed an important association with liver, muscle and lipid metabolism-related parameters. In this model, no significant contribution of body mass index, blood pressure or hormone therapy could be stated.