At the same time, similar frequencies of CD4+ Tregs (CCR7-CD45RA-CD127lowCD25+) were found in all layers of the appendix combined of children with simple and complex appendicitis (epithelium simple appendicitis median 5%, IQR 5-10% versus complex appendicitis median 10%, IQR 7-12%; lamina propria median 8%, IQR 5-9% versus median 10%, IQR 6-11%; muscular layer median 5%, IQR 4-6% versus median 6%, IQR 4-8%) (Figures 5A, B). Here, CD4 is linked to appendicitis.