Recovery from a Viral Respiratory Tract Infection: III. Specificity of Protection Conferred by Immune Spleen Cells Stimulated In Vitro

Abstract

Nude mice failed to clear influenza virus from their lungs, and eventually died from pneumonia. In this report we describe the pulmonary pathology seen in nude and BALB/c immunocompetent mice infected with mouse adapted A/Port Chalmers/1/73 (H3N2) virus. Experiments were performed in an attempt to alter the course of influenza pneumonia by passive transfer of donor immune spleen cells to infected nude mice. As we reported earlier (1,2), immune spleen cells which are restimulated in vitro have enhanced cytotoxic T cell activity and when transferred to infected nude mice effect recovery. On the contrary, immune spleen cells which are not restimulated prior to transfer augment the antibody response of recipient mice, but do not effect recovery. We now describe the specificity of this protection afforded by these immune spleen cells following secondary in vitro stimulation. These spleen cells were highly protective against lethal challenge by homologous and heterologous virus strains. The strain specific protection was highest but very significant cross subtype protection was observed. This in vivo protection reflected the cross subtype cytotoxic activity noted in target cells following in vitro stimulation prior to transfer of these immune spleen cells to recipient mice. The cross reactive protection was type A specific, since immune spleen cells stimulated by type B virus did not protect.