Decrease in microviscosity of lymphocyte surface membrar associated with stimulation induced by concanavalin A

Abstract

Microviscosity in the surface membrane lipid core of rat lymph node lymphocytes was determined by fluorescence polarization analysis of the fluorescent hydrocarbon probe 1,6-diphenyl-1,3,5-hexatriene when embedded in the membrane of intact cells, in relation to in vitro stimulation induced by concanavalin A. The apparent microviscosity in the stimulated cell population was found to be distinctively lower than in the nonstimulated cell population, based on which the membrane microviscosity of the blast cells was estimated. For each of the six experiments which were carried out the estimated microviscosity in the blast cell membranes falls between the upper and the lower limits represented by freshly drawn intact lymphocytes and leukemic cells, respectively. In accord with this observation it is suggested that a controlled reduction in the microviscosity of the surface membrane is one of the processes which take place during the stimulation of lymphocytes by antigens in vivo.