Reduced frequency of baseline sister chromatid exchanges in lymphocytes grown in antibiotics and serum-excluded culture medium.

Peripheral venous blood from man, muntjac, and cattle were grown in medium (1) containing different serum (human AB+/FCS/autologous), (2) without serum or antibiotics (penicillin and streptomycin), or (3) without both serum and antibiotics to investigate to what extent certain essential culture components used in in vitro mammalian cell cultures affect the incidence of spontaneous sister chromatid exchanges (SCEs). The observation that exclusion of only serum from culture medium enhanced the frequency of SCEs whereas exclusion of both serum and antibiotics, which influence the cell cycle kinetics to a great extent, exhibited the lowest frequency of SCEs reported so far for lymphocyte cultures, indicates that the frequency of so-called spontaneous SCEs usually observed in normal lymphocyte cultures grown in medium supplemented with serum and antibiotics is in fact an elevated frequency.