Authors from Italy and Canada have suggested that a sub-type of macrophage might be an important overlooked component of bronchoalveolar lavage fluid (BALF) in asthmatic horses. Although the predominate cells in BALF are macrophages and lymphocytes, the typical cells of interest in BALF are neutrophils, eosinophils, and mast cells. In severe equine asthma (SEA) the predominate cell of importance is the neutrophil, whereas in mild equine asthma (MEA) there could be relative increases in neutrophils, eosinophils, or mast cells, or various combinations of these cell types.
A sub-type of macrophage called Giant Multinucleated cells (GMCs) represent activated or fused forms of macrophages. The formation of GMCs is complex but may involve the cytokine interleukin (IL)-4, a pro-inflammatory cytokine involved in SEA and also in recruitment and activation of mast cells.
The authors looked at 32 horses with asthma (both SEA, n=13 and MEA, n=19) along with 10 asymptomatic control horses. Of the 19 horses with MEA 8 had increases in mast cells – so called mastocytic asthma. The horses were from Italy and Canada. They calculated the ratio of GMCs to normal macrophages and then examined the relationship of this ratio with other BALF cells changes and clinical signs.
They reported that GMCs were more prevalent in horses with SEA and that there was an association with the relative percentage of mast cells in BALF. The concluded that more work was needed but the ratio of GMSs to normal macrophages was a potential important component of SEA and mast-cell MEA.
The article is by Ilaria Basano and others from the University of Turin in Italy with Jean-Pierre Lavoie from the Universite de Montreal in Canada, Giant multinucleated cells are associated with mastocytic inflammatory signature equine asthma. The article is freely available from the journal Animals.