A subset of OKT4+ peripheral T cells can generate colonies containing mixed progeny with OKT4+ helper and OKT8+ suppressor cells

Abstract

The membrane phenotype of human T cell colony progenitors and that of their clonal progeny was studied for expression of the T4 and T8 determinants. Using clonal culture conditions, the colonies were grown in semi-solid agar medium from peripheral blood cells. Clonality was assessed using the glucose-6-phosphate-dehydrogenase isoenzyme marker. Combination of this marker with the culture of sorted cell fractions allowed us to ascribe the colony progenitors to a subset of OKT4⁺lymphocytes. The progeny consisted of the mixture of single OKT4⁺, single OKT8⁺and double OKT4⁺8⁺ cells, as determined by double staining. Double staining was performed on mass-harvested colony cells and on individual colonies expanded in liquid culture with fresh interleukin 2. Expression of the OKT8 positivity on colony cells deriving from OKT4⁺ progenitors required an interaction with radioresistant OKT8⁺ cells that were co-cultured with these progenitors. Furthermore, the functional capacities of the cell progeny were assayed on the pokeweed mitogen-driven immunoglobulin production by B cells. It was found that OKT4^T colony cells were helper whereas OKT8⁺ colony cells were suppressor cells. It is concluded that a subset of OKT4⁺ peripheral blood T lymphocytes can generate colonies containing both helper OKT4⁺ cells and suppressor OKT8⁺ cells.