To the Editor.—Heyn et al determined size distribution of lymphocytes in health and certain disease states by micrometer measurements of fixed and stained blood smears on glass slides (Am J Dis Child 125:789- 793, 1973).
It seems that interpretation of these data, in addition to those discussed by the authors, should include consideration of the manipulation of these cells prior to their size determination. Pliability, dehydration, and adherence to glass, to name a few variables, undoubtedly influence normal cell size when measured by this technique. It is possible that these factors may vary in disease.
For example, the mean cell diameter of 10μ3 found for normal lymphocytes is considerably larger than that of 7.8μ3 calculated from electronic volume determinations when it is assumed that the cells are spheres.1 Conversely, spherical volume calculated from this diameter would be 523μ3, which is twice the actual measurements of