IL-10 expression in thyroid glands: protective or harmful role against thyroid autoimmunity?

IL-10 is a cytokine which not only suppresses cellular immunity but also stimulates the humoral response. In certain animal models of autoimmunity, IL-10 exerts a protective effect against autodestruction. This study was to ascertain whether there could be a role for IL-10 in human autoimmune thyroid disease. Total RNA was extracted from snap-frozen thyroid blocks from surgical specimens. Five 'normal', five multinodular, six Graves and two Hashimoto thyroids (one euthyroid and one hypothyroid) were studied. Approximately 7 microg of total RNA from each gland were reverse transcribed with oligo-dT primers. Pre-plateau semiquantitative polymerase chain reaction (PCR) was performed with specific IL-10 primers. PCR products were run on a 1-5% agarose gel, blotted onto a N-hybond nylon membrane, hybridized with a specific internal probe labelled with gamma-32P-ATP and autoradiographed. Statistical analysis of densitometric values showed significantly higher IL-10 levels in the autoimmune than in the non-autoimmune glands. In situ hybridization and immunohistochemistry showed that the IL-10 message was located within the infiltrating lymphomononuclear cells. Histological analysis revealed that the autoimmune thyroids with the highest IL-10 levels were characterized by relevant degrees of B and T cell infiltration and also exhibited the greatest percentage of spontaneous HLA class II expression on thyrocytes. IL-10 and neutralizing anti-IL-10 antibodies were not able to regulate in vitro spontaneous or interferon-gamma (IFN-gamma)/phytohaemagglutinin (PHA)-induced HLA class II on thyrocytes. We conclude that in active autoimmune thyroiditis, in addition to the well documented production of Th1 cytokines, Th2-related lymphokines can be detected simultaneously. It can be envisaged that in this condition the role of IL-10 might be directed to the stimulation of B cell proliferation and antibody production rather than to the suppression of proinflammatory cytokine release.

A low blood lymphocyte count is associated with an expansion of activated cytotoxic lymphocytes in patients with B-cell chronic lymphocytic leukaemia.

In order to determine the relationships between CD2+ lymphocyte subpopulations and tumour mass, the immunophenotype of natural killer (NK) cells and T lymphocyte subsets was studied in 56 B-chronic lymphocytic leukaemia (B-CLL) patients and 38 healthy subjects. The patients were classified according to their blood lymphocyte count (BLC). Forty patients had BLC<30x10(9)/l (low BLC, less tumour mass) and 16 patients had BLC>30x10(9)/l (high BLC, larger tumour mass). The percentage of CD3- CD56+ cells, as well as of CD8+, CD8+ CD45RO+ and CD3+ CD57+ T subsets in low BLC patients, were higher than those found in high BLC patients. Conversely, the percentages of CD3+ HLA x DR+, CD4+ and CD4+ CD45RO+ lymphocytes were higher in high BLC patients than in low BLC patients. The CD4/CD8 ratio was decreased in low BLC patients while it was increased in high BLC patients and a significant positive correlation was found between their CD4/CD8 ratio and their BLC. We conclude that in low BLC B-CLL patients there is a decreased percentage of activated helper lymphocytes and an increased percentage of NK cells and activated cytotoxic T lymphocytes. These results suggest a role for NK cells, and helper and cytotoxic T lymphocytes in the control of tumour burden in B-CLL patients.