[In vitro regulation of the secretion of thymulin (STF) by human thymic epithelial cells].

The presence of thymulin (formerly called Facteur Thymique Sérique, FTS) in cultured human thymic epithelial cells was studied using a monoclonal anti-thymulin antibody in an immunofluorescence technique. The percentage of thymulin-containing cells increases gradually as a function of time, from 10% at day 4 to 90% at day 14. Furthermore, this increase can be prevented by the addition of thymulin in the culture medium. These data suggest a feedback control of thymulin secretion by thymic epithelial cells.