Immunoglobulin containing cells in the bronchopulmonary system of non-pneumonic and pneumonic calves

Distribution of leucocyte subsets in the canine respiratory tract

Histochemistry and immunohistochemistry were used to characterize leucocyte subsets in the respiratory tract of 15 outbred dogs (five aged <6 months and 10 aged >1 year) that had no evidence of respiratory disease. No organized nose- or bronchus-associated lymphoid tissue was observed in any of the sections examined. IgA(+) plasma cells predominated in nasal mucosa and in all parts of the bronchial tree, with fewer IgG(+) and IgM(+) plasma cells. The numbers of IgA(+) and IgM(+) cells were significantly greater in the nasal mucosa than in any other part of the respiratory mucosa. There were significantly fewer IgA(+), IgG(+) and IgM(+) cells in all parts of the respiratory tract in the puppies than in the adults. The number and distribution of mast cells and cells expressing MHC class II, L1 or CD1c were recorded. Mast cells were mainly found in the subepithelial lamina propria of nasal and bronchial mucosa and in the alveolar interstitium, and cells expressing IgE had a similar distribution. Mast cells were also present within muscle layers of the bronchial tree. The numbers of mast cells and MHC class II(+) cells were significantly greater in the nasal mucosa than in any other part of the respiratory mucosa. In the nose, carina and primary and secondary bronchus, there were significantly more mast cells and MHC class II(+) cells in puppies than in adult dogs, whereas the numbers of L1(+) cells and CD1c(+) cells in most sites were significantly greater in older dogs. There were significantly more CD3(+) and CD8(+) cells in the nasal mucosa than in any part of the bronchial mucosa. In most parts of the respiratory mucosa, CD4(+), CD8(+) and TCR alphabeta(+) cells were present in significantly greater numbers in adults than in puppies. All parts of the respiratory tract had similar numbers of mucosal CD4(+) and CD8(+) T lymphocytes. TCR gammadelta(+) cells were absent or sparse in all samples. These data, obtained from dogs without respiratory disease, will enable comparisons to be made with dogs suffering from infectious or inflammatory nasal, bronchial and pulmonary diseases.

Bovine adenovirus type 3 pneumonia in dexamethasone-treated calves

The effects of immunosuppression were examined in 1.5-month-old calves that were given dexamethasone (DM) before endobronchial inoculation with bovine adenovirus type 3 (BAV-3). Immunohistopathologically, severe necrotizing bronchiolitis with eosinophilic and basophilic intranuclear inclusion bodies was observed both in DM-treated 1.5-month-old infected calves and in non-DM-treated 7-day-old infected calves. These inclusion bodies were correlated with the detection of BAV-3 antigen and viral particles. The presence of inclusion bodies in the desquamated epithelial cells or of BAV-3 antigen, or both, correlated well with the isolated level of BAV-3 in bronchoalveolar lavage (BAL) fluid. Few immunoglobulin (IgG, IgM, and IgA)-containing B lymphocytes or CD8+ T lymphocytes infiltrated the pneumonic lesion in both the 7-day-old and the DM-treated 1.5-month-old infected calves. Thus, depletion of CD8+ T lymphocytes in calves might influence the clearance of BAV-3 from respiratory tissues.

Immune response of cattle to respiratory mycoplasmas

M. bovis and M. dispar produce very different types of response in the calf lung. The immune response of the host plays a major role in the formation of the lesion induced by M. bovis and this response is predominantly Ig mediated. In contrast M. dispar produces a much milder reaction in the lung which may be related to an ability of the mycoplasma to inhibit the host's immune response. Recovery from infection appears to be primarily mediated by IgG present in the lung and functioning in conjunction with alveolar macrophages. The immunity following vaccination which is observed in experimental studies and field trials is also likely to be mediated by the same mechanism.

Cellular and humoral elements of the lower respiratory tract of sheep. Immunological examination of cells and fluid obtained by bronchoalveolar lavage of normal lungs

Bronchoalveolar washings were harvested from the excised lungs of 68 normal sheep of 3 different age groups (A: birth to 8 weeks; B: 6 months to 2 years; C: older than 2 years). Cells and fluid obtained were examined quantitatively and functionally. Fewer cells were present in the lavage fluids of Group A sheep compared with those of Groups B and C. Macrophages were the predominant cell type (70-80%) in all sheep, with lymphocytes being second in number. The lower proportion of lymphocytes in young sheep (Group A) was attributable to lack of B-lymphocytes. As a proportion of the lymphocyte population T-cells were in the majority (60-80%) in all sheep. The proportion of null cells was higher in young sheep than in adults. Pulmonary lymphocytes from sheep of all ages responded poorly to stimulation by the non-specific mitogens phytohaemagglutinin, concanavalin A, pokeweed mitogen and lipopolysaccharide of Escherichia coli. The proportion of neutrophils was higher in sheep over 2 years old compared with younger animals. Eosinophils were present in all age groups but their proportion was greatly increased in animals over 2 years of age. Basophils were absent in young sheep and were present in only low numbers in the lungs of adult animals. In young sheep (Group A) IgG was the predominant immunoglobulin. With age, the percentage of IgG in lung fluid decreased while that of IgA increased so that IgA became the predominant immunoglobulin in older animals (Group C). In sheep of all ages IgM was present in negligible amounts. The highest value of complement (C3) occurred in adult sheep (Group B). The total white blood cell counts and differential blood counts of all the sheep were within accepted normal ranges. As in the lungs, there was an age-associated reduction in the proportions of blood T-lymphocytes and an increase in B-lymphocytes. In contrast to lung lymphocytes, those from the blood of sheep of all ages exhibited a wide range of responses to mitogens. The lowest stimulation indices were observed in the oldest sheep (Group C). The results provide background data against which assessment can be made of changes consequent upon infection with respiratory pathogens.