The course of the protective cellular reactions to the intraperitoneal administration of different influenza virus strains in newborn mice

: The features of response of the macrophagal system in relation to the development of inflammatory reaction caused by PMN-leukocytes in response to intraperitoneal inoculation of newborn white mice with various influenza virus strains of different degrees of attenuation were studied. With the A2/Frunze/76 virus highly toxic for mice the protection was exerted mostly by neutrophils whereas the participation of macrophages in host resistance under these conditions was comparatively small. With the decline of inflammatory PMN-reaction upon intraperitoneal inoculation of A2/Leningrad/337/76 virus the number and functional activity of macrophages participating in the reaction increased. Within one strain, variants in low passage levels produced greater inhibition of acid phosphatase activity in macrophages as compared with highly passaged viruses. The increased resistance of the macrophage system appeared to prevent to a certain degree the development of inflammation and contributed to a decrease of the pathological process.