Article révisé par les pairs
Résumé : The response of peripheral lymphocytes to phytohemagglutinin (PHA) and the thyroid function were investigated in 50 female patients with asymptomatic thyroiditis (AT). None of them had overt hypothyroidism at the time of the bleeding but 26 of them were on thyroid substitution therapy. The lymphocyte transformation test (LTT) showed no significant difference between untreated patients and control subjects matched for age and sex, nor between 10 patients with at least one biological sign of hypothyroidism and their matched controls. In patients, thyroid hormones administration did not influence LTT. Values of LTT decreased with age. No correlation was found between LTT and serum levels of T4, and T3, basal TSH, peak TSH after TRH injection and thyroglobulin antibodies titer. When all the patients were considered, basal TSH levels were correlated with peak TSH and were negatively correlated with T4. For peak TSH values, there was no correlation with T3 and a negative correltion with T4. In conclusion, the data show in AT: i) a normal LTT with PHA, ii) a lack of influence of the thyroid function on LTT, and iii) a possible influence of basal T4 concentration even within the normal range on TSH secretion.