The mechanism of acquired immunity against influenza

Summary

• 1. The study of the phagocytic activity in vitro of the organs of immunized mice as well as of their leucocytes should be carried out after a thorough liberation of the cells from the virucidal antibodies. A two-threefold rinsing of the emulsions of organs and of leucocytes with large volumes of an indifferent fluid does not suffice to completely eliminate the blood components. It is very advisable to use as control the cells of the normal animal preliminarily brought into contact with the fluid surrounding the cells of the actively immunized mice.

• 2. Under these conditions of the experiment the cells of the organs of hyperimmunized mice as well as the leucocytes of immune mice and horses, proved quite ineffective with regard to the influenza virus. The activity of the phagocytizing cells was always due to the presence of the virucidal antibodies of the serum.

• 3. The virus is not subjected to the harmful influence on the part of the leucocytes of the local inflammatory focus produced in the abdominal cavity by means of peptone.

• 4. The cells of the reticulo-endothelial system of mice which are highly resistant to the action of the virus are unable to reduce its vital activity. The virus injected intravenously to immune mice is inactivated at a similar rate both in the organs rich in the reticulo-endothelial tissue and poor in it. Splenectomy and blockade of the reticulo-endothelial system (by introducing colloidal dyes or saccharated carbonate of iron) do not influence markedly the resistance to the virus of normal and actively immunized mice, nor the strength and duration of the immunity elaborated in these animals by vaccination.

• 5. In the mechanism of influenza immunity the phagocytic apparatus does not play the essential rôle which is undoubtedly appropriate to the virucidal antibodies.