Reduced frequency of sister chromatid exchanges in human lymphocytes cultured with autologous serum

The incidence of sister chromatid exchange (SCE) was determined in human lymphocytes cultured with fetal calf, human AB, and autologous serum. In each individual studied, cells grown in medium supplemented with fetal calf and human AB serum showed higher yields of SCE than those cultured with autologous serum. Increased concentration of fetal calf and human AB serum in the tissue culture medium resulted in elevated frequency of SCE. No such elevation in SCE frequency was observed with increased concentration of autologous serum. The results indicate the presence of extraneous SCE-inducing factors in fetal calf and human AB serum, the nature of which is not precisely known.