Allergy-immunology glossary

ABSTRACT

Interleukin-5 [IL5] is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. IL 5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosi nophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. IL-5 has been proposed as a potential molecular target in the treatment of these diseases. In studies of asthmatics, anti-IL-5 showed minimal efficacy in patients with moderate, controlled asthma. In patients with severe, refractory asthma associated with eosinophilia, however, clinical trials have demonstrated significant reductions in asthma exacerbations. IL-6 is a pleotropic cytokine that, together with TNF-alpha and IL-lp, has been traditionally considered as a biomarker of ongoing inflammation more than as a regulatory cytokine with potential to modulate the immune response. Specifically, IL-6 has been shown to promote Th2 differentiation of CD4+ T cells while suppressing Thl differentiation through independent pathways, IL-6 can also modulate the intensity of the immune response by inhibiting T regulatory [Treg] cell development. Some studies suggest that IL'6 synergizes with IL4 [3 to promote Thl 7 differentiation. Thus, IL6 may be a key factor in determining the balance of CD4+ T cells in becoming Treg or inflammatory Thl 7 cells