Inhibition of antigen and mitogen-induced lymphocyte transformation by fetal calf serum

Use of fetal calf serum as a serum supplement in whole blood microcultures of human lymphocytes resulted in a significant suppression of in vitro stimulation with herpes simplex virus (type 1) antigen, purified protein derivative, and phytohemagglutinin. If the response to viral antigen is weak in autologous serum it may be completely missed if cultures are carried out in fetal calf serum.