ITGAX and COVID-19: Moreover, analysis of duodenal biopsies after the onset of COVID-19 symptoms in patients with macroscopically normal mucosa who underwent endoscopy for other reasons (e.g., upper abdominal pain) revealed increased numbers of CD68+, CD14+ macrophages, CD11c+ DCs, mucosal CD4+ T cells, and intraepithelial CD8+ T cells (33).