Theta-bearing and complement-receptor lymphocytes are distinct populations of cells.

In the mouse, most (or all) complement-receptor lymphocytes and theta-bearing lymphocytes are part of nonoverlapping populations of cells. This finding validates the use of these membrane markers to characterize populations of lymphocytes. In addition, it is probable that, although receptors for complement and membrane-bound immunoglobulins coexist on the same lymphoid cells, these markers are located at separate sites on the membrane.