Analysis of lymphocyte shape by visual classification, calculated measures of shape or light scattering

Direct visual assays, calculated measures of shape (Dunn and Brown, 1986) and light scattering were applied to detect shape changes and to identify human peripheral blood lymphocytes displaying different shapes (e.g., spherical cells, polarized cells, non-polar cells with surface projections). Spherical cells could be distinguished from polarized cells and from non-polar cells with surface projections by means of calculated measures of shape obtained from outline drawings, the dispersion parameter being more efficient than extension or elongation parameters. Median values for elongation and extension of polarized cells vs. non-polar cells with surface projections differed significantly provided the cell populations consisted entirely of one particular morphological class. However, if the proportion of cells changing shape is small, this may not be detectable by a significant change in the median values. Therefore, we attempted to apply calculated shape factors to identify individual cells showing a particular type of shape change. Spherical cells could be distinguished relatively easily from non-spherical cells on the basis of the dispersion values. However, it was not possible to distinguish unequivocally between polarized cells and non-polar cells with surface projections because the values overlap to a great extent. For this purpose the visual classification was found to be more reliable. Preliminary experiments with light scattering showed that median values for right angle scatter or forward angle scatter are not sensitive enough to permit the detection of a small proportion of cells changing shape.