Comparison of cell-mediated and humoral immunity in the dog lung after localized lung immunization

This study evaluated cell-mediated immunity (CMI) and antibody production serially in control and immunized lung lobes of beagle dogs. A fiberoptic bronchoscope was used to immunize selected airways in the left cardiac lung lobe with 10(10) sheep red blood cells (SRBC); the right cardiac lobe received saline as control. The immune responses produced by this localized lung immunization were evaluated in cells and fluids obtained from blood and serial bronchial washings of the immunized and control lung lobes from 5 to 21 days after immunization. The antigen-specific production of procoagulant activity (LPCA) and inhibition of migration of alveolar macrophages by SRBC antigen were used to measure CMI in lavage cells from immunized and control lung lobes. The level of specific IgM and IgG antibody in lavage fluid from the control and immunized lung lobes was evaluated with the enzyme-linked immunosorbent assay (ELISA). The results of this study showed a significantly greater percentage of neutrophils and lymphocytes in the lavage fluid from the immunized lung lobes than from the control lung lobes. The increased number of lymphocytes in the immunized lung lobes showed a positive correlation with increased antibody concentrations. In contrast to the antibody response, CMI as measured by LPCA and MIF assays was positive, with nearly equal responses in control and immunized lung lobes. Even though there were only a few lymphocytes in the control lung lobes, there were apparently enough specific immune lymphocytes present that produced mediators after antigen stimulation to result in positive CMI responses.