The Potential for DPPIV/CD26 usage as a surrogate marker for Antiretroviral Therapy Efficacy in HIV Infected populations

Background: Human Immunodeficiency Virus (HIV) viral load and CD4 + cell counts are the most commonly used markers for monitoring efficacy of anti-retroviral therapy (ART) in HIV infected individuals. The high cost of viral load monitoring limits its usage in resource limited countries, often leaving the use of CD4+ T cell counts as the only alternative. Though cheaper and more readily available, CD4+ cell counts as a measure of detecting treatment failure, is an unreliable predictor of disease progression. Hence, there is a need for more sensitive alternative, but less costly techniques for detecting treatment failure which can be used in resource limited settings. Objective: To evaluate the feasibility of using plasma CD26/Dipeptidyl peptidase IV (DPPIV) as a novel marker for clinical evaluation of treatment efficacy in HIV infected children. Method: Blood samples collected from HIV + children (n=76) before and after initiation on ART, were assessed for HIV RNA (viral load), CD4+ T-cell count and DPPIV/CD26 levels. Viral load levels were analyzed using Roche Amplicor HIV-1 Monitor Test kit; CD4+ T-Cell Counts were analyzed using BD FACS Calibur flow cytometer while DPPIV/CD 26 levels were analyzed using Human DPPIV/CD26 Quantikine ELISA kit (R&D Systems, Minneapolis MN). Results: The plasma DPPIV/CD26 levels increased significantly in children after ART initiation ( p = 0.017), while the viral load levels declined after ART initiation with subsequent CD4+ cell counts increase. The DPPIV/CD 26 increase positively correlated with viral load decrease while negatively correlating to the CD4+ cell count increase. Conclusion: These findings demonstrate an inverse relationship between DPPIV/CD26 levels and HIV viral load and the direct proportionality of CD4+ Cell counts and DPPIV/CD26 levels, suggesting potential for use of DPPIV/CD26 as a surrogate marker for evaluating HIV disease progression in children receiving anti-retroviral therapy. Key words: CD26/Dipeptidyl peptidase IV (DPPIV), ELISA, Surrogate marker, Viral Load, CD4 Count, antiretroviral.