Chronic airway inflammation alters the peripheral distribution of transferred mast cells in deficient C57BL/6-Kit W-sh/W-sh mice

Mast cells (MC) play important roles in chronic inflammatory diseases such as asthma. This study tested if transfer of bone-marrow derived MC (BMMC) to the lung could provide a new method to explore MC involvement in chronic allergic airway inflammation (CAAI). We addressed this issue by comparing MC-distribution in wild-type C57BL/6 (WT), Wsh (MC-deficient) and intravenously BMMC-transferred Wsh (Wsh+MC) mice. CAAI was induced by ovalbumin/alum injections and challenges during 90 days. Lung sections were histochemically stained to detect MC. In control mice, number of MC in the lungs was significantly higher in Wsh+MC [MC/section; Mean±SEM, 36±4] compared to WT [2±1]. No MCs were detected in Wsh mice. MC in WT mice were located around the central airway (CA) [1±0] and in the perivascular space (PVS) [1±0] whereas they were negligible in parenchyma (PA) and smaller airways (SA). In contrast, MCs in Wsh+MC mice were predominantly found in PA [16±2] and PVS [15±2] but also around CA [3±1] and SA [3±1]. Induction of CAAI in Wsh+MC mice caused increased MC number in the PA [28±6 vs. 16±2] and decreased MC number in the CA [0±0 vs. 3±1] and PVS [5±1 vs. 15±2] compared to controls. Importantly, these findings suggest that MC transfer causes a completely different condition, which might not be comparable to the WT and thus not serve as an adequate control. Instead, Wsh+MC mice may be more suitable in experiments for studying CAAI, since mast cell number, distribution and relocation in response to inflammation more closely resemble findings in the human lung.