344 Spontaneous Apoptosis of T-lymphocytes Fails to Normalize on Long-term HAART and Strongly Predicts the Recovery of CD4 T-lymphocytes G. Kaufmann*1, N. Hansjee2, C. Strub1, R. Weber3, M. Battegay1, P. Erb2 1Univ Hosp Basel, Switzerland; 2Inst for Med Microbiology, Basel, Switzerland; and 3Univ Hosp Zurich, Switzerland
Background: The depletion of CD4 T-lymphocytes is a hallmark of HIV-1 infection and mostly the result of T-cell apoptosis. The long-term effect of potent antiretroviral therapy (HAART) on T-cell apoptosis was investigated.
Methods: Spontaneous apoptosis (SA) and cellular apoptosis markers were evaluated in 55 HIV-1 infected persons receiving HAART for 48 mos (mean age 39 yrs, 82% male). The results were compared with data of 19 healthy and 18 untreated or HAART-naive HIV-1 infected individuals. SA was determined by culturing PBMCs, CD4 and CD8 T-lymphocytes for 7 days without stimulation and staining with 7-aminoactinomycin D. The expression of apoptosis markers FLIP, Bcl-2, TRAIL, TRAIL receptor 1, and Fas was determined by flow cytometry.
Results: In untreated and HAART-naïve HIV-1 infected individuals a median of 39.8% apoptotic PBMCs, 32.6% apoptotic CD4 and 65.4% apoptotic CD8 T-lymphocytes was found. SA was significantly larger than in the HIV-1 uninfected group (20.5%, 19%, 30%; p < 0.05), but long-term HAART could not significantly reduce SA despite a reduction of plasma HIV-1 RNA below 1000 copies/mL (29.9%, 21%, 47.8%; p > 0.05). Importantly, increased levels of SA of PBMCs and T-lymphocytes were strongly associated with the recovery of CD4 T-lymphocytes in low-viremic individuals (r = -0.522, p = 0.006 and r = -0.469, p = 0.002). Stratifying these individuals in three equally sized groups according to the SA of PBMCs (< 25%, 25%-41%, > 41%) revealed that CD4 count increased in 4 yrs in the first group from a median of 281-870, in the second from 140-595 and in the third from 112-275 cells/muL (p = 0.006). Increased levels of SA of T-lymphocytes were also associated with higher Fas (r = 0.459; p < 0.001), TRAIL (r = 0.497; p < 0.001) and TRAIL receptor 1 expression (r = 0.285; p = 0.021), whereas Bcl-2 and SA showed an inverse relationship (r = -0.32; p = 0.009). In contrast, c-FLIP was not associated with SA.
Conclusion: SA in HIV-1 infected individuals remains elevated despite a successful long-term virologic response. The strong relationship between residual SA of PBMCs and the recovery of CD4 count indicates that persistent apoptosis appears to be a strong determinant of immune restoration.
