Human T-cell clones with multiple and changing functions: indications of unexpected flexibility in immune response...

T-cell cloning' seems greatly to assist the reductionist approach to the dissection of cellular immune response networks. Each of the cell types involved can apparently be cloned, studied in isolation, and then recombined. The success of this approach depends, however, on the ability to maintain functionally active cells long enough to obtain sufficient working material; and the assumption that a T cell is committed irrevocably to a particular defined function, so that its properties do not change during clonal expansion. In this article Graham Pawelec and his colleagues discuss a restriction on the maintenance of clones and question the notion that a clone's function is rigidly fixed.