Cell adherence as a serious source of error in the haemacytometer count of leucocytes in artificial suspensions.

ABSTRACT

This report demonstrates a previously disregarded source of error in the count of lymphocytes that have been fixed in Turk's dilution fluid (acetic acid and gentian violet). If the dilution fluid does not contain any serum protein or other proteins, a large proporation of the lymphocytes will stick to the walls of the mixing vessel. The use of plastic or siliconized vessels does not prevent this. The number of cells which in that way will be eliminated from the suspension is dependent on several variables, such as the type of mixing procedure and mixing vessel, the compensation of the dilution fluid and the cell density. As a consequence it is difficult to give any correction factor for such a count in a haemacytometer counting chamber. More than 30% of the cells may disappear under generally obtained conditions. This source of error is to some extent also involved in the white blood cell count, despite the presence of about 1% protein in the dilution fluid from the serum and lysed erythrocytes. To prevent this loss of cells either bone serum albumin, to a concentration of 5%, or the detergent Certrimide, to a concentration of 2-5 mM, may be added to the dilution fluid.