Studies on subpopulations of theta-bearing lymphoid cells.

RECENT studies suggest there are subpopulations in T cells which differ in physical and functional properties1–4. Although indirect evidence indicates that both short and long-lived T cells exist5,6, so far there have been no direct attempts to evaluate their distribution quantitatively. The labelling index of dead and viable lymphoid cells after incubation in anti-theta-serum plus complement can be studied using permanent fixation of lymphoid cells exposed to dye exclusion technique7 combined with autoradiography.