[Cytokine measurement at a single-cell level to analyze human Th1 and Th2 cells]

Th1 cells, which produce IL-2 and IFN gamma, are responsible for cell-mediated immune responses, and Th2 cells, which produce IL-4 and IL-5, facilitate humoral immune responses. It has been shown that these two types of cells play critical roles in defensive immune responses and in immunopathological disorders such as allergic reactions and autoimmune diseases, and the methods of detecting Th1 and Th2 cells have become more important. A newly developed technique enables intracellular cytokines to be stained and detected on flow cytometry at a single-cell level. To show the existence of human Th1/Th2 cells, naive human CD4+ T cells were differentiated into Th cells in vitro, and Th1/Th2 cells were clearly demonstrated using intracellular IL-4 and IFN gamma staining. IL-4 promoted Th2 differentiation and IL-12 did Th1, as previously reported. Th1 and Th2 cells among human peripheral blood T cell population also can be detected by this technique using double staining for IL-4 and IFN gamma, and the predominance of Th1 cells among peripheral blood T cells were suggested. Measurement of intracellular cytokines is a useful technique, and will be used in the field of clinical laboratory medicine to further clarify the pathophysiology of immunological disorders.