Cytological analysis of tracheal wash and bronchoalveolar lavage fluid in health and respiratory disease in dromedary camels

Effect of age, season, and gender on bronchoalveolar lavage fluid cytology in camels

Background

Bronchoalveolar lavage fluid (BALF) samples are valued mirrors of different parts of the airway and can be used with other approaches to the diagnosis of the lower respiratory tract. Several previous studies on various animal species showed the effect of the season, gender, and age on the percentage of cells in the BALF samples.

Aim

The main aim of this study was to determine the impact of gender, age, and season on the cytological analysis in BALF of dromedary camels.

Methods

Thirteen healthy camels were involved in this study. Camels were selected based on general respiratory clinical scoring. BALF was done using a special BALF catheter. BALF samples were analyzed from dromedary camels by microscopic examination of prepared smears.

Results

The results of the BALF cytology percentage revealed that there was no variation between winter and summer in most cell types. Only the mean value of neutrophil cell percentage in BALF in winter increased significantly (10.75 ± 1.31) compared to summer (4.60 ± 0.81). The range of eosinophils was in summer (0-13) wider than in winter (0-2). A significant difference was recorded in lymphocytes, eosinophils, and epithelial cells percentage among adult and young camels. There was a high mean value of epithelial cells percentage in adult camels (10.17 ± 1.64) compared to young animals (3.0 ± 0.58). The results of the BALF cytology among males and camels showed no significant difference.

Conclusion

The present study revealed significant differences in the BALF cytology regarding age and season, but no impact on gender.

Immune cell composition of the bronchoalveolar lavage fluid in healthy and respiratory diseased dromedary camels

Background

Respiratory diseases are among the most common and expensive to treat diseases in camels with a great economic impact on camel health, welfare, and production. Bronchoalveolar lavage fluid (BALF) has been proven as a valuable sample for investigating the leukocyte populations in the respiratory tract of several species. In the present study, fluorescent antibody labeling and flow cytometry were used to study the immune cell composition of BALF in dromedary camels. Animals with clinical respiratory diseases (n = seven) were compared with apparently healthy animals (n = 10). In addition, blood leukocytes from the same animals were stained in parallel with the same antibodies and analyzed by flow cytometry.

Results

Camel BALF macrophages, granulocytes, monocytes, and lymphocytes were identified based on their forward and side scatter properties. The expression pattern of the cell markers CD172a, CD14, CD163, and MHCII molecules on BALF cells indicates a similar phenotype for camel, bovine, and porcine BALF myeloid cells. The comparison between camels with respiratory disease and healthy camels regarding cellular composition in their BALF revealed a higher total cell count, a higher fraction of granulocytes, and a lower fraction of macrophages in diseased than healthy camels. Within the lymphocyte population, the percentages of helper T cells and B cells were also higher in diseased than healthy camels. The elevated expression of the activation marker CD11a on helper T cells of diseased camels is an indication of the expansion of helper T cells population due to infection and exposure to respiratory pathogens. The higher abundance of MHCII molecules on BALF macrophages from diseased camels indicates a polarization toward an inflammatory macrophage phenotype (M1) in respiratory diseased camels. No significant differences were observed in the systemic leukogram between healthy and diseased animals.

Conclusions

Collectively, the current study represents the first report on flow cytometric analysis of immune cell composition of bronchoalveolar lavage fluid (BALF) in dromedary camels.