Objective: To investigate the distribution of granulocyte during thyrotoxicosis and the relation of granulopenia and the gathering of circulating granulocytes into the marginal pool.
Methods: Forty-five rabbits were randomly divided into 3 equal groups: epinephrine group fed with levo-thyroxin (LT4) for 14 days, injected subcutaneously with epinephrine 0.07 mg/kg, and undergoing collection of peripheral blood samples for white blood cell and granulocyte counts, free blood triiodothyroxine (FT3) and free blood thyroxine (FT4), electrocardiography, and body weight measurement; labeled group fed with LT4 for 14 days, injected subcutaneously with 131I-labeled anti-human granulocyte monoclonal antibody, and killed 6 hours later to calculate the ratio of radioactivity of heart, liver, spleen, and muscle tissues to blood (CPM/g), and control group, not fed with L-T4 but injected with 131I-labeled anti-human granulocyte monoclonal antibody on the day 14, and killed 6 hours later to calculate the ratio of radioactivity of tissues to blood.
Results: After 14-day feeding of L-T4, the heart rates of the epinephrine and labeled groups were significantly higher than those before injection, and the FT3 and FT4 levels were significantly increased;the venous WBC and granulocyte counts were significantly reduced. But the granulocyte count of 13 of the 15 rabbits in the epinephrine group increased 20 minutes after the injection of epinephrine, even becoming 2-4.8 times as high as those before the injection in 7 rabbits. The heart, liver, spleen, and muscle tissues to blood CPM/g ratios of the labeled group were all significantly higher than those of the control group (all P<0.01).
Conclusion: During thyrotoxicosis the circulating granulocytes are reduced and the distribution of circulating granulocytes is abnormal with a gathering phenomenon of the granulocytes into the marginal pool.