Apoptosis in infectious mononucleosis: its detection with the Beckman Coulter GenS hematology analyzer.

This article describes the potential of the Beckman Coulter GenS hematology analyzer for detecting and quantifying the phenomenon of elevated apoptosis found during the incubation at 37 degrees C of samples containing CD45RO+ reactive T-lymphocytes from patients with infectious mononucleosis (IM). Visual detection was carried out with the GenS DF1 scattergram (volume/scatter), and the means and SDs of lymphocyte positional parameters (volume, scatter, and conductivity) were recorded from the instrument research screen before and after samples were incubated in an oven for 4 hours. Thirty-one IM samples were analyzed, and the results obtained after sample incubation showed a mean reduction in lymphocyte volume of 34%, a 3.9% increase in scatter, and a 4% increase in conductivity. A new cluster of cells consistent with apoptotic lymphocytes appeared in the GenS DF1 scattergram. May-Gr-Giemsa staining and extended manual counting of the samples carried out at the same time to validate and quantify the apoptosis of the analyzed samples detected a significant increase in apoptotic cells from 1.2% (range, 0%-3%) to 8.37% (range, 1%-39%) after incubation. The same process was used to evaluate a control group of patients, and the possible interference of platelet aggregation and erythroblasts (nucleated red blood cells) in GenS apoptosis quantification was investigated. The final results showed that the appearance of the apoptotic cluster in the GenS DF1 scattergram occurred in 96.8% of the IM cases, although this phenomenon is apparently nonspecific because similar clusters appear in other pathologies, such as viral infections (hepatitis, cytomegalovirus, and acquired immune deficiency syndrome). Additional quantitative studies of apoptosis kinetics indicated that at least 4 hours of incubation are necessary. This finding has directed an investigation of apoptosis-inducing drugs (camptothecin, theophylline) to reduce incubation time and thereby enhance the practical application of automated apoptosis detection in the diagnosis of IM and other diseases in which the phenomenon of apoptosis occurs.