Influence of interrupted pulmonary lymph drainage on antibody responses in hilar-stripped lungs.

Lung transplantation interrupts hilar lymphatics. This may have an impact on immune responses to antigens entering the lung because the antigens cannot reach the lung-associated lymph nodes where the immune response is generated. We investigated the interruption and regeneration of lymphatics and the influence of this on antibody responses after hilar stripping in rats in three experiments: (1) visual detection of regenerated hilar lymphatics by chromolymphography, (2) observation of transport of carbon particles from the lung to the lung-associated lymph nodes, and (3) assessment of antibody responses after lung immunization with sheep red blood cells. The findings showed that hilar lymphatics were interrupted by hilar stripping and regenerated from day 7 after operation. Transport of particles to the lung-associated lymph nodes was blocked during the first week after operation but returned to normal values thereafter. Serum antibody titers were absent or low in the rats immunized on days 7 and 10 after hilar stripping; subsequently antibody responses gradually recovered in 1 month. We conclude that antibody responses to antigens in hilar-stripped lungs are impaired as long as the antigens cannot be transported through lymphatics from the lung to the lung-associated lymph nodes. These findings can explain in part why pulmonary infections occur so frequently in the initial weeks after lung transplantation.