Background: Thyroid hormones play critical roles in differentiation and metabolism of the immune system. These hormones are required for the development of immune response.
Aim of the study: to evaluate effects of thyroid hormones on immune function, in rat model with induced hypo and hyperthyroidism.
Methods: 40 Adult male rats were divided into 5 equal groups. Group I (control group). Group II (hypothyroid group) methimazole was administrated for 6 weeks. Group III (hypothyroid-treated group) hypothyroid rats were treated with L-thyroxin injection. Group IV (hyperthyroid group) rats received thyroxin injection for 6 weeks and Group V (hyperthyroid-treated group) hyperthyroid rats were treated with methimazole. At the end of the experimental period, the WBCs count were estimated, in addition to investigation of plasma IL6, TNF-α, serum level T3 and T4 levels in all groups using radioimmunoassay.
Results: Induction of hypothyroidism resulted in a significant decrease in total leukocytic count including the decline of lymphocyte, monocytes neutrophils, basophiles, eosinophils count compared to control group with a significant increase in plasma IL6 and TNF α. All these changes reversed to normal value after thyroxin treatment. On the other hand induction of hyperthyroidism caused significant decrease in neutrophil, basophil count and serum IL 6 level compared to control group with significant increase of eosinophil, monocytes, lymphocyte count and serum level of TNF α compared to control group. These findings were returned to normal after methimazole treatment.
Conclusion: Thyroid hormone dysfunction modulates the immune function including changes in leukocytic count and pro-inflammatory markers in experimental rats.
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