Systemic immunological evaluation in juvenile autoimmune thyroid disease (ATD): strong correlation between thyroid status and sIL-2R levels independent of lymphocytic thyroid infiltration.

CASTRO MS; HERZOVICH V; LAVIGNE MV; MIRAVALLE L; MANGHI MA; IORCANSKY S

Cancún, México

Congreso; XVI Reunión Anual de la Sociedad Latinoamericana de Endocrinología Pediátrica (SLEP); 2003

Sociedad Latinoamericana de Endocrinología Pediátrica (SLEP)

T- lymphocyte activation is characterized by the production of lL-2 and by the expression of IL-2 receptor (IL-2R) on the cellular surface. Following lymphocyte activation, soluble IL-2R (sIL-2R) is released. Immune responses can be mediated by cells (Th1 response), by antibodies (Th2 response) or by both (Th1/Th2). In ATD, with proven lymphocytic thyroid infiltration and a high IL-2R expression, one would expect to find a Th1 circulating cytokine pattern. In this study, we evaluated the type of immune response in juvenile ATD by measuring serum levels of INFg as Th1 marker, IL-5 as Th2 marker and sIL-2R as lymphocytic activation marker. According to thyroid status, patients were divided in: group 1, hyperthyroid patients (n = 16, aged 14.9 ± 3.7 yrs); group 2, hypothyroid patients (n = 10, aged 13.0 ± 4.4 yrs) and a control group without thyroid pathology (n = 10, aged 7.0 ± 5.0 yrs). Serum levels of sIL-2R, IL-5 and INFg were measured by ELISA (Pharmingen). Results: In pre-treatment hyperthyroid patients, sIL-2R levels were significantly higher than in the other groups (5835 ± 1812, ANOVA p<0.01). Methimazole treatment diminished sIL-2R levels to normal values (a drecrease of 64.6 ± 12.7 %). The pre-treatment hypothyroid group showed a tendency to lower sIL-2R levels, not different from the control group. After l-T4 treatment, these values increased (+ 82.0 ± 61.1%: NS). Serum sIL-2R levels showed a strong correlation with T3 (r = 0,6624, p<0.0001), T4 (r = 0,6621, p<0.0001) and with T4f levels (r = 0,6323, p<0.0001). Serum INFg levels were also higher in patients with hyperthyroidism than in hypothyroid and normal subjects (ANOVA, p<0.05) but no correlation with thyroid hormones was found. lL-5 levels were similar in all groups. These results show that serum sIL-2R levels strongly correlate with thyroid status suggesting a greater immunological activation in hyperthyroidism,  independently of the degree of  lymphocytic thyroid infiltration. This is of interest in clinical management,  since the normalization of thyroid function diminishes sIL-2R immune activation while a hyperthyroid status would perpetuate this response. Although serum INFg levels are related with hyperthyroidism, a clear correlation was not observed between these cytokine levels and serum thyroid hormones. Nevertheless, IFNg in hyperthyroid patients showed a tendency toward Th1 immune response. Our results contribute to the knowledge about the immune status in juvenile ATD, since up to now little research has been carried out in this age group, and highlight the rol of thyroid hormones in the immune system.