Artefactual low lymphocyte activity caused by platelet contamination in the mononuclear cell preparations

Platelet (PLT) contamination in preparations of mononuclear cells (MNC) produces a significant decrease (P<0.02) in lymphoproliferative activity and interleukin 2 (IL2) production. This effect was observed in MNC preparations from either healthy blood donors or polyglobulic patients. In a dose‐response curve carried out with increasing PLT number per MNC, progressive inhibition was found, reaching to 62.6% and 49.5%, respectively, to phytohemagglutinin and IL2 lymphoproliferative response and 87.8% in IL2 production, at 80 PLTs/MNC.