Endocrine Abstracts

The presence and the role of CD20⁺ T cells in humans has been described in autoimmune disorders such as multiple sclerosis and rheumatoid arthritis. In healthy subjects, CD3⁺CD20⁺ T cells are detected in all lymphatic organs and in the cerebrospinal fluid and represent about 5% of circulating T cells. Some reports described their production of high levels of IL-17A and/or IFN-γ. This study was aimed at investigating the behavior of CD3⁺CD20⁺ T lymphocytes in patients with Hashimoto’s thyroiditis, isolated or in a frame of polyautoimmunity. Sixty five patients with HT, aged from 23 to 69 years (M=14; F=51), 23 of whom in isolated form and 42 with a further autoimmune disorder [16 with gastric atrophy (HT+GA), 15 with vitiligo (HT+V) and 11 with celiac disease (HT+CD)] were investigated. Twenty sex- and age-matched healthy subjects represented the control group (HD). The chronic use of interfering drugs, the presence of severe or chronic disorders, pregnancy and lactation were considered as exclusion criteria. Whole blood samples were obtained and quickly stained with the specific fluorescent-labelled antibodies. Red blood cells were then lysed by adding 1 ml of hypotonic buffer and samples were analyzed on a FACs ARIA II Flow Cytometer (BD). The percentages of CD3⁺CD20⁺ T and the one of CD4⁺CD20⁺ T lymphocytes were similar in all groups. The subpopulation CD8⁺CD20⁺ T in the whole group of autoimmune patients was higher than in HD (P=0.0089). Those with isolated HT also showed higher percentages of CD8⁺CD20⁺ T than in HD patients, without reaching statistical significance. CD8⁺CD20⁺ T cells subset was clearly different (ANOVA:P=0.0058) in the presence of associated autoimmune disorders, as compared with HD. In particular, an increased percentage of these cells was observed in HT+GA as compared to HD (P=0.0257), unlike in patients with HT+CD, all in gluten-free diet, in whom the CD8⁺CD20⁺ T cells subset was similar to the one in HD. Interestingly, when subdivided by thyroid function, HT hypothyroid patients showed a doubled percentages of CD8⁺CD20⁺ T cells than in euthyroid patients and in HD (P=0.0115). These preliminary findings indicate that the presence of CD8⁺CD20⁺ T lymphocytes is associated with a worst thyroid function and it is differently modulated in HT patients with or without poly-autoimmunity.