HUMAN EOSINOPHILS ELABORATE THE LYMPHOCYTE CHEMOATTRACTANTS - IL-16 (LYMPHOCYTE CHEMOATTRACTANT FACTOR) AND RANTES

Eosinophils and CD4(+) lymphocytes are preferentially recruited into s ites of allergic inflammation, A role for eosinophils in the recruitme nt of CD4(+) lymphocytes has not been defined, We studied the capacity of human eosinophils to release chemoattractants for T lymphocytes. S upernatants of cultured eosinophils contained chemoattractant activity for lymphocytes, which was predominantly due to IL-16 (lymphocyte che moattractant factor) and RANTES. With neutralizing Abs, eosinophil-der ived lymphocyte chemotactic activity was diminished by a mean (+/-SEM) of 60 +/- 3% with polyclonal anti-IL-16 Ab, 69 +/- 4% with anti-IL-16 mAb, 48 +/- 3% with anti-CD4 F(ab) (IL-16 receptor blockade), 40 +/- 4% with anti-RANTES mAb, and 88 +/- 5% with a combination of anti-IL-1 6 and anti-RANTES mAbs, IL-16 and RANTES were detectable in eosinophil -derived supernatants by ELISA, Eosinophils constitutively expressed m RNA transcripts for both IL-16 and RANTES detectable by reverse transc ription-PCR and contained preformed IL-16 and RANTES demonstrable by E LISA of cell lysates and by immunocytochemistry of freshly isolated eo sinophils. Thus, eosinophils are a source of two cytokines, IL-16 and RANTES, that are chemoattractants for lymphocytes as well as eosinophi ls. These data indicate that eosinophils could contribute cytokines to enhance the recruitment of additional populations of CD4(+) lymphocyt es and eosinophils.