IL4 and asthma: Using this model, it was discovered that IL-4, via IL-4Rα, can promote IgE class switch recombination of B cells and plasma cell differentiation, worsen bronchial hyperreactivity, and induce the expression of adhesion molecules such as ICAM-1 (CD54) and VCAM-1 (CD106), priming the vascular endothelium for eosinophils extravasation (99).