In addition to T cell compartments, eosinophils are also attracted into lesions mainly via C-C motif chemokine ligand 5 (CCL5) produced by LCH cells [71] and IL-5 produced by T cells [91] (Figure 3C(c)), but the exact role of eosinophils in the pathogenesis of LCH lesions is unknown. The gene discussed is CCL5; the disease is Langerhans cell histiocytosis.