respectively. This ratio is maintained in whole blood, but may be altered slightly in the process of component prepara­ tion. Any production or processing step which intentionally decreases this ratio will result in a product which can be described as white cell depleted. It has, however, become more common to define the outcome as a residual white cell content, rather than a decrease in cellular ratios, although the latter makes more sense on theoretical grounds, since deple­ tion of white cells needs to be put in the context of any unintentional loss of red cells or platelets. The end result of this intentional processing step, therefore, is generally expressed as the residual absolute number of white cells or as the degree of difference in white cell content, the latter expressed as either a percentage change or as a logarithmic reduction.