CD40LG and infection: Additionally, within seropositive and/or positive infection history organoid SARS-CoV-2-spheromer+ CD8+ T cells, SARS-CoV-2 infection stimulated expression of the AIM markers 4–1BB, CD25, OX40 and CD40L versus mock controls, which did not occur in the seronegative donor organoids (Fig. 6d–e, Extended Data Fig. 10a).