[Efficacy of L-thyroxine (L-T4) therapy on the volume of the thyroid gland and nodules in patients with euthyroid nodular goiter (ENG)]. / Efficacia della terapia con L-tiroxina (L-T4) sul volume della tiroide e dei noduli in pazienti con gozzo nodulare eutiroideo (GNE).

The efficacy of treatment with TSH suppressive doses of L-thyroxine was evaluated by echography in 35 patients with euthyroid nodular goiter. Patients have been subdivided in two groups comparable for sex age and size of the goiter. Sixteen patients were treated for nine months with suppressive doses of thyroxine and nineteen were followed without therapy as control. Patients in treatment were then followed up for additional 9 months without therapy. The mean decrease of thyroid volume at nine months was 25% (27 +/- 10 ml vs 20 +/- 8 ml; p < 0.01). After discontinuation of treatment thyroid volume increased and had returned to base line values after nine months of follow up. In the control group mean thyroid volume had increased by 17.7% at nine months (28 +/- 17 vs 33 +/- 19 ml; p < 0.001). Thyroid nodules in response to thyroid hormone treatment showed a variable behaviour: 30.7% (4/13) of the nodules responded to the therapy with a reduction > to 25% at the ninth month; the remaining nodules were insensitive to the therapy. In conclusion suppressive thyroxine treatment is effective in reducing the goiter, nodules instead are only in part sensitive to the treatment. Thyroxine therapy of euthyroid nodular goiter must be followed for long term since upon thyroxine discontinuation there is a prompt reappearance of the goiter.

Receptors for fluoresceinated human thyroglobulin in peripheral blood lymphocytes.

Fluoresceinated human native and desialylated thyroglobulin were incubated with peripheral blood lymphocytes. 1% of the lymphocytes, in twenty samples from normal human blood donors, showed a bright granular fluorescence where neither the number nor pattern of fluorescence differed from lymphocytes from the blood of thyroiditis patients. Fluoresceinated albumin and gamma-globulin did not bind to the lymphocytes, and a 500-fold excess of native non-fluoresceinated thyroglobulin inhibited the binding and pre-incubation with anti-IgM serum abolished it. Binding with desialylated thyroglobulin was negligible, and the pattern of fluorescence was pale and uniform. Analysis by sucrose gradient centrifugation and double diffusion in agar gel showed that fluorescein dissociates thyroglobulin into 12S fragments and reduces its immunoreaction with autoantibodies. It can therefore be concluded that the 12S molecule produced by fluoresceination maintains its determinants for lymphocyte receptors, whereas further dissociation, as in desialylated fluoresceinated thyroglobulin, leads to a marked reduction in the binding with lymphocytes.

Immunological properties of Tg carbohydrates: enhancement of Tg immunoreaction by removal of sialic acid.

Immunoreaction of desialylated and native thyroglobulin was compared in sera of patients with anti-thyroglobulin antibodies by radioimmunoassay with 125I-labelled thyroglobulin. Two human thyroglobulins were iodinated both in vivo and by lactoperoxidase. After desialylation enhancement of immunoreaction was observed in several sera ranging from marginal to more than 100%. The effect was not due to iodination since it was reproducible with desialylated thyroglobulin labelled in vivo. In one serum (B.P.) a marked enhancement was only seen with one thyroglobulin suggesting that desialylation may unmask isoantigens of thyroglobulin. Glycopeptides prepared from human thyroglobulin inhibited the immunoreaction between native thyroglobulin and autoantisera. The results indicate that sialic acid masks antigenic determinants in human thyroglobulin and that carbohydrates might be the determinants involved in the process of autoimmunization.

Decrease of thyroid antibodies during pregnancy.

The behavior of serum anti-thyroglobulin (Abs-Tg) and antimicrosomal antibodies (Abs-Mc) was examined during and after normal pregnancies. The antibodies titer decreases as pregnancy progresses; they cross the placenta and are present in the fetal serum. Infants' thyroid function is not affected by this transplacentar transfer. The Abs-Tg titer increases again after delivery.