A study of factors which affect the resistance of alveolar macrophages to vaccinia virus.

Abstract

In vitro systems of pulmonary-alveolar macrophages from normal and vaccinia-immunized rabbits and their counterparts from rabbits stimulated by complete Freund's adjuvant we~ tested for their resistance to the IHD strain of vaccinia virus. It was found that alveolar macrophages could not be induced, either by vaccination or stimulation of the donor animals, to suppress the multiplication of the virus. This finding sets the alveolar macrophages apart from the peritoneal macrophages which do develop the ability to inhibit vaccinia virus when their donors are similarly treated. However, the alveolar macrophages harvested from adjuvant-stimulated animals resisted viral injury even though viral replication was taking place. This suggests that an enhanced physiological state of the alveolar macrophages is important in protecting the cells from vaccinia cytopathology. Because peritoneal macrophages develop resistance, co-incubation of the peritoneal macrophages and alveolar macrophages was done to test the possibility that interaction between two cell types could protect the entire population. This did not occur. In fact, the virus was not inhibited in the mixed macrophage culture. It was concluded that the protective mechanism of the host against a respiratory-originated viral infection is a combination of humoral and cellular immunity and the exact role of the alveolar macrophages in pox viral infection remains to be defined.