Primary immunization in the canine lung. Soluble antigen induces a localized response.

Primary immunization of the dog by intralobar instillation of particulate antigen induces an intense, localized pulmonary antibody response. In contrast, although soluble antigen can also induce local antibody responses after repeated deposition in the canine respiratory tract, its ability to induce local responses after primary immunization has not been well characterized. To document such responses, we immunized five beagle dogs using a bronchoscope to instill 10 mg keyhole limpet hemocyanin (KLH) into a single lung lobe (immunized) and saline into a contralateral lung lobe (control). Over the next 3 wk, we monitored specific immune responses in blood and bronchoalveolar lavage (BAL) fluids obtained from the immunized and control lung lobes. Primary intrapulmonary immunization of dogs with KLH resulted in anti-KLH antibody responses both in blood and in immunized and control BAL fluids. However, immunoglobulin class-specific expression of response differed between the immunized and control lung lobes. Specific IgM and IgA responses were significantly greater in the immunized lobes. In contrast, specific IgG, and cells producing specific IgG, were quantitatively similar in lavage fluids derived from immunized and control lung lobes. These studies demonstrate that primary immunization of the dog by intralobar instillation of soluble antigen stimulates a local IgM and IgA response and an IgG response that distributes to both immunized and unimmunized lung. This pattern of immunoglobulin class-specific pulmonary antibody response has the potential to importantly influence regional responses to intrapulmonary antigen.