Chromatin activation of blood lymphocytes detected by polarization microscopy and cytophotometry

Blood lymphocytes exhibit chromatin activation upon incubation with substances to which a person is allergic. Chromatin activation can be detected by polarization microscopy. In this work, different methods of evaluating lymphocyte chromatin activation were compared in nine drug-allergic and in eight control subjects. All drug allergics had skin or mucosal involvement, ranging from localized minor herpetic lesions and purpurae through wheal and circumscribed bullous lesions to serum sickness as the most severe form. The mean path difference as the measure of nuclear birefringence was obtained by a polarization microscope using both white light and 551 +/- 7 nm monochromatic light. The equation of Brace-Köhler for converting compensation into path difference for each single cell was used in calculator programs. The values were compared with readings of a cytophotometer operated in transmission mode. Allergy "scores", deriving from the analysis of chromatin activation kinetics due to serial drug dilutions, were also compared using both methods. The results indicate a linear relationship between monochromatic and white light compensation readings and an exponential relationship between mean path difference and mean transmission values at different background amplifications. Operation of the photometer at 25.8% background amplification gave the best correlating results. The two methods gave identical results for the presence (ten tests) or absence (eight tests) of allergy.