Human secondary immune responses induced by influenza in a serum-free tissue culture system

Peripheral blood lymphocytes are capable of producing antibody in response to antigenic stimulation by a recall antigen, influenza, during culture for 10 days in medium consisting of 1 part Ham's F-12 and 1 part Iscove's modified Dulbecco's medium supplemented with sodium bicarbonate, bovine crystalline insulin, human transferrin, 2-mercaptoethanol, progesterone, and bovine serum albumin. Anti-influenza antibody levels in the supernatants were determined by enzyme-linked immunosorbent assay. Optimal conditions for production of anti-influenza antibody in this serum-free medium were: influenza concentration, 0.032–0.125 HAU/ml; day of harvest, 10; and cell concentration, 3.0–4.0×10⁵ cells in 200 μl of medium per well. Use of serum-free medium will allow examination of the effects of various additives to tissue culture without concern for unknown factors or potential interaction with serum.