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

In an examination of the immunoglobulin containing cells in the respiratory mucosa of three-month-old non-pneumonic calves, IgA was found to be the predominant plasma cell type. In calves with cuffing pneumonia there was a marked increase in the plasma cell population in the bronchial wall and IgG1 cells became the major cell type. Similarly in calves with an exudative type of pneumonia IgG1 plasma cells were the significant cell type in the respiratory mucosa but the total number of plasma cells was similar to that found in the non-pneumonic animals. The immunohistochemical results suggest that IgA and, to a lesser extent, IgM are both transported across the mucous membrane via bronchial epithelial secretory cells and submucosal glands.