The potential impact of CD4+ T cell activation and enhanced Th1/Th2 cytokine ratio on HIV-1 secretion in the lungs of individuals with advanced AIDS and active pulmonary infection

Bronchoalveolar lavage fluid (BALF) provides a source of mucosal CD4+ T cells. We investigated the physiological properties of T lymphocytes from BALF and blood and their role on the dynamic of HIV-1 replication among AIDS patients with active lung infections. Pulmonary CD4+ T cells consist mainly of effector memory cells (CD45RO+ and CCR7−) with increased expression of activation markers (HLA-DR+ and CD69+) when compared to the blood counterpart. We observed a high frequency of BALF cells capable of secreting HIV-1-Ags suggesting that the local lung environment may support favorable conditions for CD4+ T lymphocytes harboring HIV-1 DNA to initiate the viral cycle. Nevertheless, the high number of IFN-γ-producing cells and the predominance of Th1 immune response in the lung could limit the secretion of HIV-1 RNA. In conclusion, the capacity of activated CD4+ T cells to produce HIV-1 is driven by both the level and quality of cellular activation in the lung.