The process of fluorochromasia involves the hydrolysis by cells of fluorescein diacetate resulting in an intracellular accumulation of fluorescein. The polarization of the fluorescence of the fluorescein appears to depend on the intracellular fluorescein concentration, the distribution of fluorescein within the cell and the viscosity of the cell cytoplasm.
The parameters of fluorochromasia were studied with thymocytes from normal BALB/c mice and from mice bearing an intraperitoneal NK/LY/R lymphoma. During the course of tumour proliferation, the response toT-cell mitogens increased whereas the response to other lectins,e.g. wheat germ agglutinin, decreased or remained unaltered. These changes were consistent with the corresponding increase in immunocompetent cells within the thymus, observed by microelectrophoresis. Thus this sensitive technique provides a useful quantitative assessment of the lectin-lymphoid cell interaction.