Comparison of lymphokine secretion and mRNA expression in the CD45RA+ and CD45RO+ subsets of human peripheral blood CD4+ and CD8+ lymphocytes

Abstract

Flow cytometric analysis of human peripheral blood T lymphocytes demonstrated that the majority of the CD4+ cells were CD29+ or CD45RO+ "mature" cells while the CD8+ cells were primarily CD45RA+ "native" cells. After an initial separation into CD4+ and CD8+ cells and a secondary separation into CD45 subsets, lymphokine secretion was assessed after phorbol 12-myristate 13-acetate and ionomycin or fixed anti-CD3 stimulation. Within the respective CD45 subsets, CD4+ cells produced more interleukin (IL)-2, IL-4, and IL-6; but the CD8+ cells secreted more interferon-gamma and granulocyte/macrophage-colony-stimulating factor. Tumor necrosis factor-alpha secretion was similar in the matched CD45 subsets. Northern analysis revealed a parallel pattern of lymphokine mRNA expression in the four lymphocyte subsets. These results suggest that human CD8+ peripheral blood lymphocytes have a significant capacity to secrete lymphokines, and that the low lymphokine production observed in unseparated CD8+ cells reflects the higher percentage of less functional CD45RA+ cells.