Human thymic epithelial cells in serum-free culture: changes in cytokine production in primary and successive culture periods.

Human thymic epithelial cells (TEC) have been cultured in a growth factor-defined serum-free medium, and their production of cytokines in primary cultures and during three subsequent culture periods was investigated. TEC produced interleukin (IL)-1 alpha, IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in all culture periods, as detected by the use of ELISA and B9 cell assay. The highest concentrations of the cytokines were found in the tertiary and quaternary subculture period, but in these subcultures the production decreased progressively. There was no clear correlation between cell proliferation and cytokine production in the cultures.