The effect of specific antibody on the generation of cytotoxic T lymphocytes and the recovery of mice from influenza virus infection.

A study has been made of the effect of humoral antibody on the generation of specific cytotoxic T cells (Tc) in the spleen or lungs after intravenous injection or intranasal inoculation of infectious influenza virus. Antibody injected before or at the same time as virus inhibited completely the generation of Tc in the spleen. If injected 1 h after virus, the inhibition was reduced by 50%, and little inhibition occurred if antibody was injected 6 h after virus. This suggested that antibody failed to influence Tc generation once infection of stimulating cells had occurred. Antibody injected intravenously 24 h after intranasal inoculation of virus into normal mice did not affect the level of cytotoxic activity present in the lungs, and trace amounts only (less than 1 log10 EID50) could be recovered from the lungs at 6 days. As there is a high titre (greater than 6 log10 EID50) of infectious virus in the lungs of mice 24 h after infection, this represents a very efficient control mechanism. The same protocol carried out with athymic mice gave only a partial clearance (c. 3 log10 EID50) of virus in the lungs. It was suggested that a major role of humoral antibody was to limit infection by the virus, and in this respect it complemented the action of Tc.