HIV-specific cytotoxic T lymphocytes against alveolar macrophages: specificities and downregulation.

ABSTRACT

To analyse the evolution of alveolar-lymphocyte-mediated cytotoxic activity directed against autologous alveolar macrophages (AM), cytotoxic assays against various HIV+ target cells were performed in a cohort of 75 patients with HIV-associated lymphoid interstitial pneumonitis (LIP) studied at distinct stages of HIV infection. Our data confirm that alveolar HIV-specific cytotoxic T lymphocytes (CTL) against AM were detectable before AIDS in patients with CD8+ LIP. Mild CD8+ lymphocytic alveolitis occurs silently in 62% of stage II and III patients with no respiratory symptoms. In these cases, the lack of spontaneous alveolar-lymphocyte-mediated cytotoxic activity against autologous AM may contrast with the detection of primary alveolar CTL specific for HIV proteins such as nef. In AIDS patients, the alveolar CTL lytic efficiency against both AM- and HIV-antigen-expressing cells can be inhibited by a suppressor factor produced by alveolar CD8+ CD57+ cells. Therefore, spontaneous CTL lysis of AM may be (1) limited to a subgroup of patients with active LIP and (2) controlled by distinct mechanisms, including suppressor phenomenons, and HIV replication levels in AM.