CHICKEN GROWTH-HORMONE, TRIIODOTHYRONINE AND THYROTROPIN-RELEASING-HORMONE MODULATION OF THE LEVELS OF CHICKEN NATURAL CELL-MEDIATED CYTOTOXICITY

Newly hatched White Leghorn male chicks received dietary supplements of either Triiodothyronine (T3) or Thyrotropin Releasing Hormone (TRH) until 8 weeks of age. Chicken growth hormone (cGH) (10-mu-g/kg BW) was injected into different chicks twice daily for 1 week starting at 7 weeks of age. Separate groups received both T3 and cGH. Natural cell-mediated cytotoxic (NCMC) activity against different target cells was tested. It was found that cytotoxic activity in cells involved in NCMC against P815 mouse mastocytoma was stimulated by cGH alone or in combination with T3 (1 ppm). These findings indicate that cGH and T3 stimulate NCMC activity; and that the cells responsible for this activity may be Natural Killer (NK) cells.