Cytolytic Activity of Pulmonary and Systemic Lymphoid Cells from C57BL/6 Mice Following Intrapulmonary or Intraperitoneal Immunization with Allogeneic Tumor Cells

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Abstract
To demonstrate whether specific cytotoxic T cells could be induced in lung parenchyma, C57BL/6 mice were immunized by the intrapulmonary route with allogenic tumor cells ([mouse mastocytoma] P815). Ten days after administration of 20 .times. 106 allogeneic cells, peak concentrations of cytotoxic cells were found in lung, tracheobronchial lymph node and spleen. With reduction in immunizing dose, lytic activity disappeared from spleen and lymph node, but persisted in lung. The cytolytic activity was specific for the immunizing alloantigen, was abolished by antitheta serum and could not be attributed to macrophages. C57BL/6 mice were immunized by the i.p. route with 20 .times. 106 P815 cells. The expected cytolytic activity was found in spleen and lymph nodes; unexpectedly, high levels of cytolytic activity were also found in pulmonary lymphocytes. This activity was confirmed using a wide range of effector to target cell ratios in the assay system. Quantitative cytolytic assays demonstrated that the maximum rate of cytolysis by pulmonary lymphocytes, obtained from mice immunized i.p., exceeded, by 10- to 20-fold, the rate of cytolysis by pulmonary lymphocytes obtained from mice receiving intrapulmonary immunization. Cytolytic T lymphocytes appear in lung parenchyma after intrapulmonary or i.p. immunization; the i.p. route apparently is far more efficient than the intrapulmonary route. This cell-mediated immune mechanism potentially is available for host defense of respiratory tissue.