In response to dietary protein, antigen-experienced CD4+ T cells accumulated in the intestinal epithelium and modulated the expression of cytotoxic genes on conventional and regulatory CD4+ T cells. Blocking mucosal addressin cell adhesion molecule 1 prevented the retinal infiltration of b7+ CD4+ T cells and ameliorated the loss of retinal ganglion cells. SPECIES COEXISTENCE Tropical trees deter similar neighbors Tropical forests host an unusually high diversity of tree species. [Extracted from the article]