Mononuclear cell subsets in bronchoalveolar lavage fluid duringDictyocaulus viviparusinfection of calves: a potential role for γ/δ TCR‐expressing cells in airway immune responses?

Abstract

Mononuclear cell populations in the lungs of calves infected with Dictyocaulus viviparus were studied during primary infection and reinfection in order to identify cells involved in development of protective immunity to parasitic bronchitis. Three groups of calves were either inoculated with 500 third-stage larvae at both weeks 0 and 10 (n = 6), inoculated only at week 10 (n = 6), or remained uninfected (n = 3). The animals were monitored weekly by collection of bronchoalveolar lavage fluid (BALF), blood and faeces. Among mononuclear BALF-cell populations, the gamma/delta TCR-expressing cells showed a pronounced transient increase in proportion as well as in relative cell size 2 weeks post primary infection, whereas CD4-, CD8-, Ig- and CD14-expressing cells showed no significant differences related to the infection. The increase in gamma/delta TCR-expressing cells coincided with significantly increased proportions of eosinophils and recovery of adult worms in BALF. After reinfection, gamma/delta TCR-expressing cells increased again, but not until week 3 post inoculation, whereas eosinophils were increased by week 2 and reached higher levels than after primary infection. After reinfection, establishment of D. viviparus was less successful than after primary infection. In conclusion, these results indicate a role for gamma/delta TCR-expressing lymphocytes in the pathogenesis of D. viviparus infection.

Cytokine mRNA expression in bronchoalveolar lavage cells during Dictyocaulus viviparus infection in calves

“…The experiment was designed to compare cellular immune responses to D. viviparus in naïve and immune animals (approved by the Ethical Committee for Animal Experiments, Uppsala, Sweden, C26/3) and has been described in detail . In brief, three groups of 2‐ to 3‐month‐old calves were included in the study.…”

“…The inoculum contained 500 L3 larvae per animal of a D. viviparus isolate originating from Intervet, the Netherlands, and was given orally. Bronchoalveolar lavages were performed once per week on each calf, starting week ‐1 as described previously . The concentration of nucleated cells in the recovered BALF was determined by counting in Türks solution, and ≤ 6 × 10 6 BALF cells were collected for use in the present study.…”

“…Also in D. viviparus ‐infected cattle, there are indications that Th2‐type responses are induced. For instance, a prominent eosinophilia was induced in the circulation as well as in worm‐infested lung tissue of infected cattle . In chronic infections, increased proportions of mucous producing cells and hyperplasia of bronchial smooth muscle are also observed .…”

γδ T Lymphocytes Coordinate Eosinophil Influx during Allergic Responses

“…The parallel accumulation of γδ T lymphocytes and eosinophils in the tissue has also been demonstrated in another model of lung biased Th2 response: parasitic bronchitis triggered by the infection with Dictyocaulus viviparus (a bovine lung worm). Increased γδ T cell and eosinophil numbers were detected in the BAL fluid of infected calves, indicating the role of γδ T cells in the pathogenesis of D. viviparus -induced Th2 response and possible in eosinophil accumulation (Hagberg et al, 2005). An interesting piece of information that must be highlighted from this paper is that eosinophils recovered from BAL fluid of N .…”

The immune response to parasitic helminths of veterinary importance and its potential manipulation for future vaccine control strategies

“…However, eosinophils isolated from calves do bind to the surface of D. viviparus in vitro and do inhibit their mobility (Knapp and Oakley 1981), which may suggest an effector role for eosinophils during disease. Hagberg et al (2005) have also reported that eosinophils in BAL peak 2 weeks after primary infection and again 2 weeks after secondary challenge (12 weeks after primary challenge), and this correlates strongly with peaks in γδ T cells in BAL. Furthermore, eosinophils and γδ T cells are found in greatest numbers compared with other granulocytes or lymphocytes in BAL from infected cattle.…”