Mitogen stimulation of lymphocytes from patients with epidemic influenza.

The in vitro responses to PHA (phytohemagglutinin) of lymphocytes from 14 patients with influenza A and 4 patients with influenza B infection were found decreased as compared with the responses to the same mitogen demonstrated in lymphocytes obtained from the same patients after recovery. Lymphocytes from 6 of the patients with influenza A were examined for PWM (pokeweed mitogen) stimulability and a decrease was found during the influenza infection. The decrease of PHA response during the acute stage of the disease was observed in the presence of autologous as well as of fetal calf and allogeneic AB serum. Possible mechanisms causing this impaired function of lymphocytes are discussed.