• hormonal imprinting;
  • interleukin-6;
  • IL-6;
  • cytokines;
  • mast cells;
  • lymphocytes

Single treatment of newborn rat with human recombinant interleukin-6 (IL-6) durably increases IL-6 content in certain cell types of the adult animal. Peritoneal mast cells contain a high quantity of IL-6, in contrast to controls which contain no IL-6. In addition, many other (mainly lymphatic) cells of the peritoneal fluid contain IL-6. However, IL-6 is present in the control thymocytes, in smaller amounts than in the neonatally IL-6 imprinted cells. In the blood, the number of IL-6 containing cells also increases after imprinting (lymphocytes and developing forms of mast cells).