THYMIC HORMONE CONTAINING CELLS .3. EVIDENCE FOR A FEEDBACK-REGULATION OF THE SECRETION OF THE SERUM THYMIC-FACTOR (FTS) BY THYMIC EPITHELIAL-CELLS

Abstract

Cells containing the serum factor (FTS), as measured by indirect immunofluorescence, were studied in mice either FTS-depleted by injection of anti-FTS monoclonal antibodies or immunization against FTS coupled to bovine serum albumin (FTS-BSA), or FTS enriched by multiple injections of synthetic thymulin (FTS-Zn). Injections of thymulin did not significantly depress FTS secretion. Long term elimination of FTS from peripheral blood caused a great increase in the thymic intracellular content of FTS, as evidenced by the higher number of FTS-containing cells observed with immunofluorescence. The data could provide the first evidence of a feedback control of thymic endocrine function.