Leukotriene B4 induces enhanced migration of fish leucocytes in vitro

Leukotriene B4 (LTB4) was found to induce enhanced migration of the eosinophilic G1 granulocyte of the dogfish Scyliorhinus canicula in the migration under agarose assay. Higher levels of LTB4, however, were required to produce this effect than with mammalian neutrophils under similar conditions. It is postulated that this may be due to the dogfish granulocytes possessing fewer receptors for LTB4 than their mammalian counterparts. The eosinophilic G3 granulocyte was also tested using the same assay but results were inconclusive. The effect of LTB4 on dogfish G1 and G3 granulocytes was also monitored with the bipolar shape formation (BSF) assay. LTB4 induced BSF in both granulocyte types, and this method appeared to be more sensitive than the migration under agarose assay. Whether the enhanced migration observed is a result of chemotaxis or chemokinesis is not determined. This present study represents the first known report of the function of LTB4 in a non-mammalian vertebrate.