Lymphocyte ectoenzyme activity compared in healthy persons and patients seropositive to or at high risk of HIV infection.

We measured two ectoenzymes, ecto-5'-nucleotidase (NT) and dipeptidyl peptidase IV (DP) in the peripheral blood lymphocytes of various groups of HIV-infected patients because of the previous implied relationship of these enzymes to immune function. NT expressed as mean nmol/h per mg protein (+/- s.d.) was significantly depressed in the HIV-seropositive asymptomatic (42 +/- 32; P less than 0.01) and AIDS groups (14 +/- 7; P less than 0.002) when compared with a healthy HIV-seronegative male population (83 +/- 27). The NT activities in asymptomatic HIV-seropositive and HIV-seronegative high risk groups (53 +/- 30) were not significantly different from one another but both groups had significantly higher enzyme activities than the AIDS group (P = 0.01 and less than 0.002, respectively). The seronegative high risk and normal healthy group had similar NT activities. DP activities expressed as mean nmol/h per mg protein (+/- s.d.) in both seropositive asymptomatic (0.188 +/- 0.038) and high risk seronegative (0.180 +/- 0.05) groups had higher enzyme activities than the healthy seronegative (0.117 +/- 0.015; P = 0.02 and 0.05, respectively) and AIDS group (0.096 +/- 0.036; P = 0.002 and 0.02, respectively). The healthy seronegative group had DP activities not significantly different to the AIDS groups. Similarly the high risk seronegative and healthy seropositive group had similar DP activities. These results taken together indicate that measurement of both DP and NT should be evaluated prospectively as a monitor of the clinical progression of HIV infection.