Multiple biologic activities of a cloned inducer T-cell population.

The mouse T-cell clone Ly1+2(-)/9, belonging to the Ly1 set, displays the following functions in vitro: (i) augmentation of immunoglobulin output by B cells; (ii) stimulation of bone marrow cells to produce colonies composed of granulocytes, macrophages, or both; and (iii) proliferative stimulation of T-cell clones belonging to other Ly sets. These functions are induced by Ly1+2(-)/9 cells themselves and by supernatants of Ly1+2(-)/9 cultures and are not evinced by tested clones belonging to other Ly sets. The agent or agents responsible for colony formation and for B-cell stimulation had an apparent molecular weight of 45,000-50,000 and could not be physically separated. The T-cell stimulating agent(s) had an apparent molecular weight of 30,000 and could be separated from the agent(s) that acts upon colony formation and B cells. Thus, clone LY1+2(-)/9 produces at least two soluble products that induce or augment activities of at least three other differently programmed cell sets.