Platelets roll and adhere to the vascular bed in response to allergen challenge in allergic mice

In an allergic inflammatory disease such as asthma, platelets can migrate through lungs in response to allergen (Pitchford, S. et al. Am J Resp Crit Care Med 2008; 177:604-612). Platelet activity and their interaction with the endothelium in response to allergen requires further investigation. The aim of this study was to investigate the vascular interactions of platelets in allergic mice following allergen challenge using intravital microscopy of the mouse cremaster muscle (CM) to visualize platelets in real time.Mice were sensitised intra-nasally with 25 μg house dust mite extract (HDM), 10 times over 2 weeks. 100 μg HDM was then administered intra-scrotally and the CM prepared for intravital microscopy 24 hours later; an injection of 1.6 μg CD49b antibody (0.1 mL i.v.) was used to visualise platelets.Fluorescently labelled platelets in HDM sensitised-HDM challenged groups compared to saline immunised-HDM challenged groups had increased rolling (from 17.9 ± 1.9 to 32.1 ± 2.3 (rolling platelets/10 sec); P≤0.001) and adhesion (from 1.0 ± 0.2 to 2.0 ± 0.2 (platelets/30 μm2); P≤0.01) events in post capillary venules. The number of leukocytes present within the CM also increased in HDM sensitised-HDM challenged groups (from 11.8 ± 0.9 to 27.8 ± 1.9 (leukocytes/30 μm2); P≤0.001), demonstrating that an allergic inflammatory response in CM can be achieved using this model.We reveal that localized platelet accumulatio...
Source: European Respiratory Journal - Category: Respiratory Medicine Authors: Tags: Allergy and immunology Source Type: research