Actin content in lymphocytes: a proposed correlation with their recirculating properties.

The DNAase inhibition assay, which allows for the titration of monomeric and total actin content per cell, has been applied to various subpopulations of rat lymphocytes. We found that characteristic values are associated with functionally distinct subpopulations. Thus, thymus-dependent (T) lymphocytes have significantly higher monomeric and total actin per cell than bone marrow-derived (B) lymphocytes, irrespective of the separation procedure used (in vitro or in vivo). Moreover, these values appear to increase with the differentiation state of the cells within the T compartment (i.e., from thymus to lymph node to thoracic duct lymphocytes). The fact that the observed trends overlap the known in vivo recirculating abilities of the populations tested prompted us to discuss the possible involvement of intracellular actin in the control of the cell-surface deformability.