On the other hand, IL-4 from Th2 cells promotes proliferation of Th2 cells and expression of intravascular endothelial cell adhesion molecules that induce monocyte, eosinophil, and lymphocyte aggregation at inflammatory sites, improves the effects of B cells and T cells, promotes the humoral immune response, and aggravates allergic reactions. Here, IL4 is linked to allergic disease.