Cytokine production by mature and immature CD4-CD8- T cells: αβ-T cell receptor CD4-CD8- T cells produce IL-4

Abstract

This study follows our previous investigation describing the production of four cytokines (IL-2, IL-4, IFN-γ, and TNF-α) by subsets of thymocytes defined by the expression of CD3, 4, 8, and 25. Here we investigate in greater detail subpopulations of CD4-CD8- double negative (DN) thymocytes. First we divided immature CD25-CD4-CD8-CD3- (CD25- triple negative) (TN) thymocytes into CD44+ and CD44- subsets. The CD44+ population includes very immature precursor T cells and produced high titers of IL-2, TNF-α, and IFN-γ upon activation with calcium ionophore and phorbol ester. In contrast, the CD44- subset of CD25- TN thymocytes did not produce any of the cytokines studied under similar activation ..