Local T‐cell activation after segmental allergen challenge 
in the lungs of allergic dogs

Abstract

SUMMARYDogs with immunoglobulin E (IgE) allergy for ragweed that are sensitized by intrapulmonary exposure to ragweed can be used to study the pulmonary immune response that is important in allergic asthma. Using this model, we tested the hypothesis that T lymphocytes are activated locally in the airways shortly after allergen exposure of the lungs. The airways of six allergic dogs and three non-allergic dogs were exposed to ragweed by segmental allergen challenge (SAC). T-cell subsets and T-cell activation in blood and bronchoalveolar lavage (BAL) fluid were measured by flow cytometry before SAC and at 4, 24 and 72 hr thereafter. SAC caused a statistically significant increase in the percentage of major histocompatibility complex (MHC) class II-positive CD4 and CD8 T cells in BAL fluid and a significant increase in the mean fluorescent activity of MHC class II from 4 hr after SAC onward. This activation was significantly different from that found in cells from lung lobes challenged with saline, or from lung lobes in non-allergic dogs challenged with ragweed. The percentage of CD45RA bright CD8 cells increased significantly in allergic dogs after both ragweed and saline challenges. This was significantly higher than in non-allergic dogs. We conclude that T-cell activation in the airways of dogs can be measured after in vivo activation of the cells by measuring MHC class II and CD45RA expression in BAL fluid T cells. Furthermore, in allergic dogs, T cells are activated locally in the lungs within 4 hr after exposure to ragweed allergen. These results suggest a role for T lymphocytes in the development of late-phase allergic reactions in the airways.

Characterization of the Bronchoalveolar Lavage Fluid by Single Cell Gene Expression Analysis in Healthy Dogs: A Promising Technique

“…Common analyses performed on BALF include determination of total (TCC) and differential cell counts (DCC) (including macrophages, neutrophils, lymphocytes, eosinophils, and mast cells count), cytological examination of cytospin preparations, bacterial cultures and detection of specific respiratory pathogens using quantitative polymerase chain reactions ( 13 , 14 ). Only few studies have characterized the lymphocyte populations in the canine BALF by flow cytometry ( 15 – 19 ) while the other cell types have not been studied. In depth examination of BALF cellular composition and subpopulations as well as the comparison of these cell subpopulations in healthy and diseased conditions could lead to the identification of new cell subsets involved in disease and could help to better understand the pathophysiology of lung diseases, the cell adaptations in disease context as well as to find new or more specific therapeutic targets ( 6 , 20 ).…”

Animal models of asthma: utility and limitations

“…One of them is a dog model with T cells locally activated in the lungs within 4 hours after exposure to ragweed allergen. 56 …”

Nonhuman primate models of asthma

“…There are, however, important differences between the two species, including techniques for measuring pulmonary function, chronicity of the disease process, and species differences in expression of, or responses to, key cytokines and mediators ( 2 ). Large animal models of asthma have been developed in dogs ( 4 ), sheep ( 5 ), and monkeys (principally rhesus and cynomolgus macaques) ( 6 – 11 ). All have proven useful for studies of pharmacology and physiology and for preclinical development of drugs that provide symptomatic relief for asthma.…”