Abstract
The peripheral blood lymphocyte populations were determined in 10 patients during the acute phase of influenza and 6–8 weeks after recovery. The percentage of T-lymphocytes, demonstrated by their binding sheep erythrocytes non-specifically (E-rosette forming cells), was decreased during influenza. A relative and absolute increase of non-T-lymphocytes could be shown by the determination on these cells of receptors for activated C'3 (EAC-rosette forming cells).