Differential secretion of tumor necrosis factor-α and granulocyte/macrophage colony-stimulating factors but not interferon-γ from CD4 compared to CD8 human T cell clones

Abstract

Tumor necrosis factor‐alpha (TNF‐α) is a pleiotropic lymphokine which may have important regulatory effects on immune responses. It is shown here that eight alloreactive CD4 T cell clones (TCC) secreted significant amounts of TNF‐α after stimulation with either specific alloantigen or 12‐O‐tetradecanoylphorbol 13‐acetate together with the calcium ionophore ionomycin (up to 50 ng/ml/24 h/10⁶ cells) whereas CD8 TCC failed to do so (max. 2 ng/ml/24 h/10⁶ cells). The CD8 TCC also secreted markedly less granulocyte/macrophage colony‐stimulating factor than the CD4 cells. However, this was not indicative of a general decrease of lymphokine production by CD8 cells because CD4 and CD8 TCC both secreted similar amounts of interferon‐gamma. These results show that regulatory CD4 lymphocytes can produce large amounts of TNF‐α, whereas CD8 effector cells cannot do so.