CD4 and Recurrent lower respiratory tract infections: However, even though the IL-17A/TNF/IFN-γ producing alveolar CD4+ T cell responses against S. pneumoniae in HIV-infected adults are preserved, there are other immune processes in the alveolar space that have been shown to be compromised in ART-naïve HIV-infected adults, which can lead to an increased risk to lower respiratory tract infections.