Characterisation of ovine mast cells derived from in vitro culture of haemopoietic tissue.

Ovine mast cells generated in vitro from bone marrow (BMMC) were compared with mucosal mast cells (MMC) isolated from parasitised abomasum. Ultrastructurally, the granules of BMMC were partially developed and immature. Both cells types contained beta-hexosaminidase, arylsulfatase, histamine, dopamine and sheep mast cell proteinase (SMCP). Greater amounts of beta-hexosaminidase, but less SMCP, histamine and arylsulfatase were present in BMMC. Stimulation with calcium ionophore A23187 caused the secretion of granule constituents and generation of leukotriene C4 by BMMC in a dose-dependent manner. An additional 3H]diisopropylfluorophosphate-binding 31,500 mol. wt. serine esterase, antigenically related to SMCP (27,000 mol. wt.) was present in cultures of BMMC but was not detected in isolated MMC. Both enzymes were detected in BMMC by Day 7 of culture and were secreted concomitantly following stimulation of BMMC with ionophore.