| Graves disease is an autoimmune disease. Currently, the mechanism of the disease is not yet clear. Multiple factors are involved in the occurrence of Graves disease. Such as abnormal immune function, heredity, infection, sex hormone, lithium agent and spiritual factor. Studies have shown that there are antibodies against TSH receptor in serum of patients with Graves disease, known as the TSH-receptor antibody (TRAb).TRAb and TSH can both bind with TSH receptor and the biological effects are occurred by signal transduction pathway. The biological effects as follows: the hyperplasia of thyroid cells , the increasing of synthesis and secretion of thyroid hormone, Resulting in the occurrence of GD. At present, TRAb has been as the most important autoantibody and characteristic marker. In recent years, with in-depth study of the mechanism of incidence of hyperthyroidism, cytokine has been emphasized.The cytokine is a kind of low-molecular-weight protein secreted mainly by immune cells. it has the activity of regulating and is a major factor mediating immune response,And cytokine is a category of polypeptide with extensively biological effects ,Including mainly tumor necrosis factor (TNF)αandβ, interleukin (IL),interferon(IFN)α,βandγet al. It has been found that cytokine isrelevant with the incidence and development of thyroid disease. The further studies of cytokine are important for understanding the pathogenesis of GD , deciding of the therapeutic effect and the prognosis and exploring new methods of treatment.With the increasing of reports on the cytokines, interleukins have been further researched, such as IL-1, IL-2, IL-6, but the studies on the relationship between GD and IL-8 are less. IL-8 is a kind of multi-source cytokine and multi-functional bioactive peptide synthesized by mononuclear cells and endothelial cells. It has chemo taxis to T lymphocytes, neutrophils and basophiles, in which T lymphocytes are most sensitive to IL-8. IL-8 play an important role in tissue localization of T lymphocytes, circulation of lymphocytes, inflammation and infiltration of inflammatory cells. IL-8 has lasting effects because it is tolerated to degradation of endopeptidase in serum and exudates. So, IL-8 is a key factor in inflammation. Recently, there are many reports on IL-8 in autoimmune thyroid disorder.To explore the relationship of IL-8 with the mechanism of Graves disease and search prognostic index of GD, we detected the levels of IL-8 in serum and ratio of FT<sub>3 / IL-8 and FT<sub>4 / IL-8 before and after I-131 therapy to patients withGraves disease and analyzed with the relationship of IL-8 with TRAb and thyroid function,138 blood samples were collected in this study, in which 40 cases with health examination were as normal control group, 12 were male, 28 female. aged 22～56, and mean age was 32±10 years. The function of Heart, liver, renal was normal and they had no thyroid disease and other autoimmune disease, no allergies, infections and genetic history; Study group consisted of 98 cases of Graves disease. The untreated group consisted of 69 cases. Of them, 21 were male, 48 female. aged 25-59, and mean age was 34±11 years, history was 1 months～5 years. All patients were diagnosised diffuse goiter with hyperthyroidism according to the clinical symptoms and thyroid function tests (TT<sub>3,TT<sub>4,FT<sub>3,FT<sub>4,hTSH and thyroid 131I intaken test) and not treated. The thyroid gland swelled from light to mediate, without nodules, no allergy infection occurred, without merging invasive exophthalmos and other complications or other autoimmune diseases; the relapsing group included 29 cases. of them, 9 were male and 20 female, aged 23～54 years, and average age were 33±8 yeas. The patients with GD had cured after I-131 therapy, but the symptoms and signs of hyperthyroidism again emerged and the levels of thyroid hormone increased again and hTSH decreased.In the morning, 5 ml of venous blood was taken and plasma was separated in untreated group and relapsing group before and in 1st,3rd and 6th month after I-131 administration, and TT3, TT4, FT4, FT4 and hTSH were measured immediately. the rest of blood were preserved under-200C. the detected method was same in control group as that in GD group.The serum concentrations of TT3, TT4, FT3, FT4 and IL-8, TRAb were measured By RIA. The serum concentration of hTSH was determined by IRMA. The results showed:1.The levels of IL-8 in patients with GD were significantly higher than that in control group(P <0.01). there were no significant differences between the levels of IL-8 in 1st month after I-131 administration and that before therapy (P>0.05);the serum concentrations of IL-8 significantly decreased by comparing 3rd,6th month after I-131 administration with before therapy and 1st month after therapy(P<0.01),but the level of IL-8 was significantly higher in 3rd,6th month after treatment than that in normal group (P<0.01). The level of IL-8 reached normal level in 18th month after treatment.2. The level of IL-8 was significantly higher in GD relapse than that in control group and remission group (p <0.01). There was no significant difference between relapse and GD early-onset group before treatment (P> 0.05). 3. the ratio of FT3 / IL-8 and FT<sub>4 / IL-8 in GD group was significantly higher thanthat in the control group. no statistical differences in the ratio of FT3 / IL-8 and FT4 / IL-8 were observed before treatment in the patients with GD and in the 1st month after I-131 administration. the ratio returned to normal in 3rd month after therapy .there was no significant difference between the ratio of FT3 / IL-8 and FT4 / IL-8 in 6,18th month after therapy and that in 3rd month after therapy. The ratio was stability in 18th month after treatment. 4. The tendency of change of TRAb was consistent with that of IL-8 in different periods of treatment.Conclusion: 1. IL-8 is a kind of cytokine directly involved in the immune response. The level of IL-8 in patients with Graves disease significantly increased, and gradually decreased after treatment. But the time when the level of IL-8 reached normal (after 18 months) was significantly later than that when FT3, FT4 and TSH which are index reflecting thyroid function (after 3 months). Suggesting that the restore of immune function lags behind its own thyroid function in patients with Graves' disease.2. The level of IL-8 returned to normal in 18 months after treating, while the ratio of FT3 / IL-8 and FT4 / IL-8 has reached to normal in 3 month post-therapy ,which was consistent with that of FT3, FT4 and TSH, this indicated that the ratio of FT3 / IL-8 and FT4 / IL-8 can reflect function ofthyroid more clearly than IL-8 single. 3. The change of level of IL-8 was consistent with that of TRAb in patients with Graves disease in different stages before and after treatment, showing the levels of IL-8 were correlated with that of TRAb,suggesting that IL-8 may play an important role in the pathogenesis of Graves disease. Therefore, IL-8 can be used to an effective index of observing prognosis of Graves disease after treatment with 131I and immune function. |
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