Serum concentrations of interleukin-5 and the production of lymphocytes in reactive eosinophilia.

The concentrations of interleukin-5 (IL-5) in serum and in IL-2-stimulated lymphocyte culture medium (L-IL2-CM) prepared from patients with reactive eosinophilia were measured by enzyme-linked immunosorbent assay. The serum IL-5 concentration was increased in 16 of 34 cases. The concentrations of IL-5 in L-IL2-CM were increased in 8 of 21 patients.