ESPE Abstracts

Background: In autoimmune thyroiditis type Hashimoto the key role in thyrocytes destruction plays the spontaneous cytotoxic activity of T cells, and antibodies dependent mechanisms are of a less value. A spontaneous cytotoxicity is associated with the number and degree of activity of NK cells. An important role in this process plays perforin contributed in permabilization of target cells.

Objective and hypotheses: The aim of the study was to evaluate the number of NK cells, their cytotoxic ability and the perforin expression in peripheral CD56 cells in children with Hashimoto’s thyroiditis.

Method: Ten children at the age 10–17 years diagnosed with Hashimoto’s thyroiditis were enrolled and nine healthy children as the control group. In every child were evaluated: the number of NK cells (CD56+), cytometric test of cytotoxic ability of NK cells and perforin expression in CD56+ cells.

Results: In cytometric test of cytolysis with K 562 cells the values of spontaneous cytotoxicity of NK cells were significantly higher in children with Hashimoto’s thyroiditis in comparison to healthy children (P=0.04), whereas the percentage of circulating NK cells in both groups was comparable. Simultaneously in children with Hashimoto’s thyroiditis the expression of perforin in CD56+ cells was significantly lower than that observed in healthy children (P=0.04).

Conclusion: In children with Hashimoto’s thyroiditis in comparison to healthy children a higher cytotoxic activity of T cells is observed with simultaneously decreased perforin expression in NK cells. Probably this apparently paradoxical effect might be a consequence of hyperactivity of NK cells.