Which cells modulate immune activity and can lead to autoimmune reactions?

T-cells play a pivotal role in modulating immune activity and can indeed be involved in the development of autoimmune reactions. They are a type of lymphocyte central to the adaptive immune response. There are various subsets of T-cells, such as helper T-cells and regulatory T-cells, each with distinct functions. Helper T-cells assist other immune cells in recognizing and responding to pathogens, while regulatory T-cells help maintain tolerance to self-antigens, preventing autoimmune reactions.

When the T-cell population becomes dysregulated or when there is a failure in the mechanisms of tolerance, these cells can mistakenly target the body's own tissues, leading to autoimmune diseases. For example, certain T-cells might recognize self-antigens as foreign, thereby triggering an immune response against the body’s own cells.

In contrast, B-cells primarily produce antibodies, neutrophils are essential for the innate immune response and are involved in responding to infections, and macrophages play a role in phagocytosis and antigen presentation. While all these cells contribute to immune responses, they do not have the direct regulatory functions that T-cells possess, which are crucial in the modulation of immune activity and the potential for autoimmune reactions.