Clinical studies on autoimmune mechanisms of the thyroid Part II. Leucocyte migration inhibiton studies in Hashimoto's thyroiditis and in Graves' disease (author's transol)

Abstract

The Leucocyte migration inhibiton test (LMT) using the agaraose plate technique according Clausen was performed in 19 patients with Hashimoto's thyroiditis, 23 patients with Graves' disease, and in 17 normal subjects. A series of leucocyte suspensions was preincubated at 37 degrees C for 30 min. with crude thyroid extract (Crude), purified thyroglobulin (Tg) and thyroid microsomes (Micr) in concentrations of 500, 300 and 100 muml, respectively together with phosphate buffer saline (PBS) as the control. Then, each of the aliquots of 7 mul of leucocyte suspension 1.5 million leucocytes, preincubated with various antigens of PBS, was placed into 4 wells, 2 in each of 2 agarose plates, followed by a 2nd incubation for 24 hours at 37 degrees C, in 2 per cent CO2 with 98 per cent atomospheric air, resulting in a pH of between 7.2 and 7.4. After the incubation, the migration areas were studied and measured by planimetry. The degree of migration inhibition was expressed as a migration index (MI); that is, the ratio of the average extent of migration of the leucocytes cultured with antigens to that of control. The MI values for normal subjects against Crude, Tg and Micr were 97.6 +/- 6.8 (mean +/- S.D)%, 97.8 +/- 4.2%, and 95.5 +/- 5.3%, respectively. Low MI values, below 2 S.D. of the normal, were regarded as positive results. The rate of positive LMT in patients with Hashimoto's thyroiditis were 32%, 46% and 31% against Crude, Tg and Micr, respectively. In Graves' disease, they were 35%, 50% and 41% for the same antigens, respectively. In 68--68% of patients with Hashimoto's thyroiditis or Graves' disease, positive LMT was at least shown with one of the three antigens. In Graves' disease, there was no correlation between MI values and the presence of long acting thyroid stimulator (LATS). In untreated patients with Hashimoto's thyroiditis and Graves' disease with a short clinical course, the migration inhibiton factor against Tg or Micr was found to be positive in a remarkably high rate. On the other hand, the levels of circulating antibodies in the serum tended to show high titers in patients with long duration, comparing with those with short duration. From the histological findings obtained by needle biopsy of thyroid tissue, grade of lymphocytic infiltration was found to be significantly correlated with the degree of reduction in MI values. From these observations, it is concluded that MIF against Tg can easily be detected by the agarose plate technique and that cellular immunity may play a more important role in the initial phase of autoimmune thyroid diseases than the later phase, in which the serum levels of circulating antibodies are becoming predominant.