IL5 and hypereosinophilic syndrome: Furthermore, eosinophils can produce interleukin-5, which stimulates proliferation of eosinophils and other inflammatory cells.32 The presence of intralesional eosinophils in T-cell lymphoma, at least in the canine peripheral T-cell lymphoma,33 is described and there are few reports of T-cell lymphoma associated with severe hypereosinophilic syndrome in cats,2,30 demonstrating a close interaction between T-cells and eosinophils.