Plasma adenosine deaminase activity among HIV1 Clade C seropositives: relation to CD4 T cell population and antiretroviral therapy

BACKGROUND: Plasma adenosine deaminase and its isoenzymes(s) activities have been used as diagnostic marker for intracellular parasitism, including HIV infection, and malignancy of immune cells. HIV infection being primarily targeted against CD4 cells, it would be of interest to relate the activity of total plasma ADA and isoenzymes fractions to immune status and antiretroviral therapy. METHODS: In the present study, plasma total ADA activity (ADAT) including ADA1 and ADA2 isoenzyme(s) were assayed among HIV seropositive Clade C (n=90) comprising both asymptomatic (n=71) and symptomatic (n=19) and compared with that of HIV seronegatives (n=35). RESULTS: A significant increase in the activity of ADAT (16.30+/-0.80 v/s 6.18+/-0.30) as well as ADA1 (6.50+/-0.42 v/s 2.34+/-0.16) and ADA2 (9.79+/-0.53 v/s 3.85+/-0.23) isoenzyme(s) among the asymptomatic as well as the symptomatic subjects as compared to respective controls was noted. Increase in plasma ADAT activity, including ADA1 and ADA2 isoenzyme(s), were found to have negative correlation with CD4 counts (r, -0.273; p<0.05). The increased plasma ADAT activity among the asymptomatic HIV seropositive with CD4 counts>500 (13.2+/-1.65; p<0.01) as well as those who were on antiretroviral therapy (19.31+/-1.36; p<0.001) was evident. CONCLUSIONS: These findings suggest that plasma ADA can be a sensitive marker of an ongoing biological insult to host tissues either because of infection and/or side effects of medication. Measurement of plasma ADA activity, along with serological evidence for HIV infection may provide an alternate laboratory tool to monitor intracellular parasitism including secondary infection vis a vis the after effects of therapeutic outcome.