CD69 and infection: However, lung ALI organoids from seropositive and/or positive infection history individuals also manifested adaptive immunity to in vitro SARS-CoV-2 infection in CD8+ T cells, with induction of (i) cell surface AIM markers 4–1BB, OX40, CD40L and CD25 and (ii) the presence, expansion and activation of SARS-CoV-2 peptide:MHC spheromer-reactive T cells, consistent with an anamnestic virus-specific memory response.