Identification and characterization of a homologue of the pro-inflammatorycytokine Macrophage Migration Inhibitory Factor in the tick, Amblyomma americanum

Studying tick feeding and digestion, we discovered in a cDNA library from p artially fed Amblyomma americanum ticks the first known arthropod homologue of a human cytokine, the pro-inflammatory Macrophage Migration Inhibitory Factor (MIF). The tick origin of the MIF cDNA clone was confirmed by sequen cing a genomic fragment that contained the full-length tick MIF gene with t wo introns. Antiserum to a tick MIF-specific peptide as well as antiserum t o complete tick MIF revealed the expression of tick MIF in the salivary gla nd and midgut tissues of A. americanum, ticks. In an in vitro functional as say, recombinant tick MIF inhibited the migration of human macrophages to t he same extent that recombinant human MIF did.