CD74 and COVID-19: This strong increase in CD74 expression on CD8+ T cells during COVID-19 was found in virtually all analyzed patients, and was also demonstrated for the cell populations EM (mean: 4.0% on day 1, 50.0% on day 7; Figure 6G) and E (mean: 1.9% on day 1, 40.2% on day 7; Figure 6H).