beta-Cyclodextrin as a substitute for fetal calf serum in the primary antibody response in vitro

Fetal calf serum (FCS) must be present at 10% in the culture medium for optimally eliciting the primary antibody response to sheep erythrocytes (SRBC) in murine lymphocytes. The response was no longer observed when FCS was reduced to less than 1%. However, we found that the addition of 250-500 micrograms/ml beta-cyclodextrin (beta-CD) to RPMI 1640 medium containing 1% FCS restored the immune response to a level comparable to that observed in 10% FCS-containing medium. beta-CD did not further augment the response in the presence of 10% FCS. The order of effectiveness of various cyclodextrin compounds tested was as follows: beta-CD (100) greater than alpha-CD(30) greater than gamma-CD(10) greater than heptakis (2,6-O-dimethyl)beta-CD (less than 1). The in vitro antibody response varied drastically depending on the lot of FCS added to the culture medium. The important observation was that even a deficient lot of FCS could elicit the antibody response as efficiently as a good lot if it was added to the culture medium at 1% in combination with beta-CD. beta-CD was also effective in inducing the primary antibody responses to both SRBC and dinitrophenylated Ficoll in serum-free RPMI 1640 medium containing bovine serum albumin, insulin and transferrin. In serum-free conditions, the responses were 40-50% of those in serum-containing medium. beta-CD did not increase the number of antibody-forming cells nonspecifically, nor did it show a significant mitogenic activity and cytotoxicity. These data suggest that beta-CD is a useful material as a serum substitute in inducing primary antibody response in vitro.