Which type of cells provides long-term immunity by preventing reinfection from the same disease?

Memory T cells are specifically designed to provide long-term immunity. When the body is exposed to a pathogen for the first time, such as a virus or bacterium, T cells are activated and respond to the infection. Some of these activated T cells, instead of immediately battling the pathogen, become memory T cells after the infection has been cleared.

These memory T cells persist in the body long after the initial infection has resolved, maintaining a form of "memory" of the specific pathogen. If the same pathogen invades again in the future, these memory T cells can recognize it quickly and mount a faster and more robust immune response compared to the body's first encounter. This rapid and potent response is crucial for preventing reinfection from the same disease, thus providing long-term immunity.

In comparison, helper T cells primarily assist other immune cells in responding to infections, regulatory T cells help maintain immune tolerance and prevent autoimmunity, and naive T cells are those that have yet to encounter their specific antigen and participate in their first immune response.