Sample Aging Profoundly Reduces Monocyte Responses in Human Whole Blood Cultures

Human whole blood cultures are widely used for the investigation of physiological pathways and drug effects in vitro. Detailed information on the effect of “sample aging” (the time span between blood collection and experimental start) on the experimental outcome is not readily available in the public domain. We studied the effect of sample aging on the ability of immune cells to respond to cell-specific immune triggers (LPS, PMA/ionomycin, and SEB). Sample aging at room temperature profoundly inhibited the LPS-induced monocytic cytokine release in minimally diluted whole blood cultures. The reduction ranged from 20–50% after 30 minutes to 80–100% after 10 hours and differed between cytokines (IL-1β, IL-2, IL-6, IFNγ, and TNFα). Sample storage at 4°C or 37°C even worsened this. PMA/ionomycin- and SEB-induced cytokine release, both mainly T-cell-driven, were also reduced by sample aging but to a lesser extent (20–50% after 24 hours). Intracellular cytokine staining revealed that the number of LPS-responding cells was not impacted by sample aging and reduced LPS responsivity could also not be explained by apoptosis or downregulated TLR4 expression. Thus, we speculate that sample aging induces an inhibitory pathway downstream from TLR4 in monocytes. These results underline the importance of quick sample handling when investigating innate immune responses in whole blood, especially for monocyte responses.

Distinct Mitochondrial Disturbance in CD4+T and CD8+T Cells From HIV-Infected Patients

BACKGROUND

Mitochondrial dysfunction has frequently been found in HIV-infected patients regardless of whether they received antiretroviral therapy (ART). Accumulating evidence suggests that HIV-infected patients exhibit marked changes in mitochondrial membrane potential (MMP), reactive oxygen species (ROS) accumulation, adenosine triphosphate generation, mitochondrial mass (MM), mitochondrial DNA, etc. However, mitochondrial toxicity in CD4T and CD8T cells caused by different levels of HIV progression and ART is poorly understood.

METHODS

Blood samples were obtained from 97 ART-naïve HIV-infected patients with different CD4T cell counts, 97 nucleoside-reverse transcriptase inhibitors-exposed HIV-infected patients, and 25 HIV-negative subjects. MMP, ROS, and MM in CD4T and CD8T cells were assessed by flow cytometry.

RESULTS

In healthy subjects, the levels of MMP and MM in CD4T cells were higher than those in CD8T cells. HIV infection led to an increase in MM in CD4T and CD8T cells, but mainly influenced MMP in CD8T cells and ROS accumulation in CD4T cells. MM in CD4T and CD8T cells gradually increased after the loss of CD4T cells. Although the dynamic changes in MMP in CD4T cells were different from those in CD8T cells during highly active ART, MM in both CD4T and CD8T cells was significantly decreased after 2 years of therapy, but increased again after 3 years.

CONCLUSIONS

HIV infection and antiretroviral therapy both led to mitochondrial disturbances in CD4T cells and CD8T cells; however, the abnormal changes in mitochondrial parameters in CD4+T cells were different from those in CD8T cells caused by HIV infection and antiretroviral therapy.