Inhibition of T-lymphocyte colony formation by inhibitors of mitochondrial protein synthesis.

A double layer technique which requires an underlayer of peripheral blood leucocytes, in addition to phytohaemmagglutinin (PHA) in the overlayer, to obtain good T-lymphocyte colony formation, was used to assess the effect of two inhibitors of mitochondrial protein synthesis, chloramphenicol and ethidium bromide. A significant inhibition of the colony growth of peripheral blood T lymphocytes was observed when either of the drugs was incorporated in the underlayer. The inhibitory effect was always smaller (c. 50%) when the drugs were added to the overlayer. These findings point to the existence of a T-lymphocyte colony stimulating factor(s), released mainly by the leucocyte-rich underlayer and essential for T-colony formation, the production of which is inhibited by these mitochonrial inhibitors.