THE EFFECT OF LATENT ADENOVIRUS-5 INFECTION ON CIGARETTE SMOKE-INDUCED LUNG INFLAMMATION

The aim of this study was to test the hypothesis that latent adenoviru s (Ad)5 infection increases the lung inflammation that follows a singl e acute exposure to cigarette smoke. A recently developed model of lat ent adenoviral infection in guineapigs was used. Twelve animals were i nfected with Ad5 (10(8) plaque-forming units) and 12 animals were sham -infected. Thirty five days later six Ad5-infected and six sham-infect ed animals were exposed to the smoke from five cigarettes. The remaini ng animals were used as controls for both infection and smoking. As ma rkers of inflammation, the volume fraction of macrophages, T-lymphocyt es, neutrophils and eosinophils were measured by quantitative histolog y. We found that latent Ad5-infection alone, doubled the number of mac rophages in the lung parenchyma and that smoking alone, doubled the vo lume fraction of neutrophils in the airway wall and the volume fractio n of macrophages in the lung parenchyma. Neither viral infection nor s moking, alone, had an effect on T-lymphocytes or eosinophils. However, the combination of viral infection and smoking doubled the T-lymphocy te helper cells and quadrupled the volume fraction of macrophages in t he lung parenchyma. We conclude that in guinea-pigs, latent adenovirus 5 infection increases the inflammation that follows a single acute ex posure to cigarette smoke, by increasing the volume fraction of macrop hages and T-lymphocyte helper cells.