IMMUNOLOGY OF LOWER RESPIRATORY-TRACT .3. CONCENTRATIONS OF ANTIGEN AND OF ANTIBODY-FORMING-CELLS IN PULMONARY AND SYSTEMIC LYMPHOID-TISSUES OF DOGS AFTER INTRA-PULMONARY OR INTRAVENOUS ADMINISTRATION OF SHEEP ERYTHROCYTES

Abstract

The distribution of antibody-forming cells to sheep erythrocytes among canine pulmonary and systemic lymphoid tissues differs distinctively depending on whether antigen is administered by the intrapulmonary [i.p.] or the i.v. route. After local (i.p.) immunization, antibody-forming cells are restricted to the lung and regional lymph nodes; after i.v., they are widespread. To test the hypothesis that the tissue distribution of antigen is an important determinant of the resultant distribution of antibody-forming cells, dogs were immunized with radioiodinated sheep erythrocytes i.p. or i.v. After 4 days the concentrations of tissue-bound radioactivity and of antibody-forming cells in various lymphoid tissues were compared. The distribution of tissue-bound radioactivity among lymphoid tissues was clearly determined and different depending on the route of immunization. After i.p. administration, radioactivity was bound to lung and hilar lymph nodes; after i.v., it was found in the lung, liver, spleen and occasionally hilar nodes. Antibody-forming cells appeared in those lymphoid preparations which contained tissue-bound radioactivity. The exception was that locally applied antigen elicited antibody-forming cells in the lung poorly, despite the fact that abundant antigen remained localized to the lung. Notably, i.v. immunization resulted in the appearance of antibody forming cells and cell-bound radioactivity in the lung. Apparently the distribution of antigen among tissues is a major determinant of the distinctive patterns of appearance of antibody-forming cells after different routes of immunization.