Mouse Thymocyte Membrane Uptake of Polyadenylic-Polyuridylic Acid Complexes

Indirect immunofluorescence revealed that 80 ± 4% of isolated mouse thymocytes were found to have membrane uptake of poly (A:U). Mice previously injected with hydrocortisone demonstrated a reduction to 20-30% in numbers of fluorescent thymocytes. Preincubation of thymocytes with DEAE-dextran did not increase the percentage of fluorescent cells. These findings suggest that medullary thymocytes bind poly (A:U) to a lesser degree than cortical thymocytes. Several mechanisms of thymocyte uptake of poly (A:U) are suggested including adsorption to the membrane and/or rapid penetration through the membrane.