EFFECTS OF IN-VIVO THYROID-HORMONE TREATMENT ON THE EXPRESSION OF INTERLEUKIN-2 RECEPTORS ON AVIAN SPLENOCYTES

Comell K strain chickens received a diet supplemented with 0, 0.1 and 1.0 ppm T-3 from the day of hatching. At 28 days of age, splenocyte su spensions were prepared and analyzed by flow cytometry for interleukin -2 receptor (IL-2R) and CD3 expression. The low T-3 dose increased the percentage of resting small cells expressing IL-2R while the mean flu orescence for this marker was enhanced only after mitogenic activation . This treatment did not alter the number of larger cells positive for IL-2R but did increase their mean fluorescence following mitogenic ac tivation. The high T-3 dose depressed the numbers of cells positive fo r IL-2R and their mean fluorescence amongst all splenocyte preparation s. Both levels of T-3 enhanced the numbers of CD3-positive cells in al l cell preparations. These results suggest that the IL-2R expression c an be modulated by in vivo T-3 supplementation and that these correlat e with the previously demonstrated changes in IL-2-like activity. The regulation of IL-2R expression provides one mechanism through which th yroid status may regulate immune function.