Binding and functional effects of thyroid stimulating hormone on human immune cells

Area of Science:

• Immunology
• Endocrinology
• Cell Biology

Background:

• Thyroid stimulating hormone (TSH) is primarily known for its role in regulating thyroid function.
• The presence and function of TSH receptors on immune cells are not well understood.
• Investigating TSH interactions with the immune system may reveal novel regulatory pathways.

Purpose of the Study:

• To investigate the expression and functional relevance of TSH receptors on human immune cells.
• To determine the binding patterns of TSH to various immune cell populations.
• To explore the functional effects of TSH on lymphocyte activity and immunoglobulin production.

Main Methods:

• Flow cytometric analysis was employed to assess the binding of biotinylated TSH.
• Human peripheral blood mononuclear cells (PBMC) and purified lymphoid subsets were utilized.
• In vitro activation of lymphocytes was performed using Staphylococcus aureus Cowan and phytohemagglutinin (PHA).

Main Results:

• TSH exhibited significant binding to monocytes and natural killer (NK) cells.
• Marginal binding was observed on T and B lymphocytes, with increased binding on activated B cells.
• TSH did not stimulate DNA synthesis or cAMP levels in lymphocytes but moderately increased Ig production in activated B cells.

Conclusions:

• TSH receptors are expressed on human immune cells, notably monocytes and NK cells.
• TSH may play a role in modulating B cell function, including immunoglobulin production.
• These findings suggest a potential link between the thyroid and the immune system mediated by TSH.