Appearance of antibody-forming cells in lymphocytes from the lower respiratory tract of the dog after intrapulmonary or intravenous immunization with sheep erythrocytes.

To investigate the mechanisms of expression of humoral immunity in the lower respiratory tract, dogs were immunized either locally (intrapulmonary) or systemically (intravenous) with low doses of sheep erythrocytes. Bronchoalveolar cells obtained by pulmonary lavage and hilar lymph nodes were assayed during the primary immune response for their concentrations of antibody-forming cells with the Jerne plaque technique. Antibody-forming cells consistently appeared among bronchoalveolar cells after intravenous immunization but failed to accumulate in this cell population after local administration of the identical dose of sheep erythrocytes. By contrast, after local immunization, antibody-forming cells appeared in the hilar lymph nodes in generally greater concentrations than after intravenous immunization. The results demonstrated that the anatomic site of presentation of this particulate antigen to the lung (intravascular versus intra-alveolar) as well as the dose of antigen are important determinants of the distribution of antibody-forming cells in these 2 pulmonary lymphoid tissues. The data suggested that bronchoalveolar lymphocytes and hilar lymph node cells function independently in the expression of humoral immunity in the lower respiratory tract.