Immune responses after localized lung immunization in the dog.

The immune response in immunized and unimmunized bronchoalveolar spaces, as well as in the blood, was measured after localized deposition of antigen in the lung. Using a fiberoptic bronchoscope, groups of dogs were immunized with sheep red blood cells (SRBC) deposited into a single airway of the left apical or right apical lung lobes. Bronchoalveolar cells were obtained by lung lavage through the fiberoptic bronchoscope from the immunized lung lobe, as well as from lung lobes that did not receive antigen. Lavage cells and blood samples were collected at 3 to 21 days after immunization. The total number of lymphocytes, macrophages, and polymorphonuclear leukocytes, and the number of lymphoid cells producing anti-SRBC IgM and IgG antibodies were determined. Our results indicated that the highest number of antibody-forming cells (AFC) were found in the immunized lung lobes. An elevated, but significantly lower number of AFC were observed in the unimmunized lung lobes. The number of IgM and IgG AFC in the blood reached peak concentrations 3 to 7 days earlier than the AFC in the lung. We concluded from our data that the blood is an important source of the AFC found in the lung.