A simple method for determining the extent of cellular contamination in peripheral blood lymphocyte preparations

A method is described for calculating, from the size distribution of the cells, the extent of cellular contamination of lymphocyte concentrates prepared from venous blood. The precision of this method was checked by direct comparison with differential leucocyte counts obtained by direct microscopy on 29 samples chosen because they showed a wide range of intensity of contamination. By virtue of its technical simplicity, the method has proved useful in a diagnostic service laboratory for checking the purity of lymphocyte preparations either before performing lymphocyte function tests or after a period of 24 h in tissue culture.