CD4 and COVID-19: Our data indicate that CSF2/GM-CSF–expressing cells are found in the lungs and coexpress IL17A. These data, in addition to the presence of CD4+CCR6+ T cells in the lung tissue as well as GM-CSF and IL-17A in the BALF, provide clinical evidence that TRM17 cell–associated cytokines are present in patients with severe COVID-19.