Proliferation of thymocytes in relation to T-cell receptor beta-chain expression.

During proliferation and differentiation of maturing thymocytes, T-cell receptor beta-chain products are first expressed in the cytoplasm. Only subsequently are they expressed on the cell surface, presumably as part of the alpha beta/CD3 receptor complex. This study uses double immunofluorescence labelling to identify these cytoplasmic and surface phases separately in relationship to cell-cycle parameters. The use of a mitotic arrest agent and tritiated thymidine autoradiography both show that cells with cytoplasmic beta-chains are in cell cycle, whereas cells with surface beta-chains are cycling slowly, if at all.