We have previously used the following protocol for metaphase analysis using whole blood:
"Peripheral blood was drawn from this donor and other healthy donors into heparinized vacutainers. Separate cultures were set up from each blood sample, using 1 ml blood in 9 ml RPMI 1640 medium (with 25 mM Hepes buffer and L-glutamine), containing 20% fetal bovine serum (Bio Whittaker) and 2.5% phytohemagglutinin (PHA, Gibco BRL). The cultures were incubated in dark, at 37 C in a humidified atmosphere of 95% air and 5% CO2."
S.M.J. Mortazavi , T. Ikushima , H. Mozdarani . Variablity of chromosomal radioadaptive response in human lymphocytes.. International Journal of Radiation Research. 2003; 1 (1) :55-61