Adrenaline‐induced mobilization of T cells in HIV‐infected patients
The present study aimed to investigate lymphocyte mobilization from peripheral cell reservoirs in HIV‐infected patients. Nine HIV‐infected patients on stable highly active anti‐retroviral therapy (HAART), eight treatment‐naive HIV‐infected patients and eight HIV− controls received a 1‐h adrenaline infusion. The adrenaline infusion induced a three‐fold increase in the concentration of lymphocytes in all three groups. All HIV‐infected patients mobilized significantly higher numbers of CD8+ cells but less CD4+ cells. All subjects mobilized CD45RA+CD62L+ and CD8+CD28+ cells to a lesser extent than CD45RO+CD45RA− and CD8+CD28−cells. Furthermore, high numbers of CD8+CD38+ cells were mobilized only in the HIV‐infected patients. It was therefore predominantly T cells with an activated phenotype which were mobilized after adrenaline stimulation. It is concluded that the HIV‐associated immune defect induced an impaired ability to mobilize immune‐competent cells in response to stress stimuli. Furthermore, the study does not support the idea that CD4+ T cells are trapped in lymph nodes by HIV antigens, because untreated and HAART‐treated HIV‐infected patients mobilized similar numbers of CD4+ T cells. Finally, no evidence was found for the existence of a HAART‐induced non‐circulating pool of CD4+ T cells.