Effects of inhaled insoluble 239PuO2 on immune responses following lung immunization

To determine if inhaled 239PuO2 suppresses immunity in lung-associated lymph nodes, Chinese hamsters were exposed to a polydisperse aerosol of 239PuO2 produced at 11500C. The mean lung burden of these animals was estimated to be 10 nCi at 8 days after exposure. At 128, 256 and 400 days after exposure, sham exposed controls and experimental animals were immunized by intratracheal instillation of 1 x 108 sheep red blood cells (SRBC). Six days later, they were sacrificed and the number of antibody forming cells (AFC) in lung-associated lymph nodes, spleen and cervical lymph nodes was evaluated. Results of these studies indicated that the number of AFC in lung-associated lymph modes was significantly lower in animals exposed to 239PuO2. Only a few AFC were found in spleen and cervical lymph nodes after intratracheal immunization and the number in exposed animals was not significantly different than in the controls. These data indicate that even though the 239PuO2 exposure had suppressed immune responses in lung-associated lymph nodes, their filtering capacity was unaffected and antigen did not translocate to the spleen. We conclude that, at the sacrifice intervals evaluated, the immune function of lung-associated lymph nodes was suppressed and that distant lymphoid tissue (e.g., spleen and cervical lymph nodes) did not replace the immune function of the lung-associated lymph nodes