Here's a breakdown of their role:

* T helper cells (Th cells): These cells are responsible for recognizing antigens and activating other immune cells, including cytotoxic T cells and B cells.

* Cytotoxic T cells (Tc cells): These cells directly kill infected cells and cancer cells by releasing cytotoxic substances like granzyme and perforin.

* Memory T cells: These cells "remember" specific antigens and can quickly mount an immune response upon re-exposure.

* Regulatory T cells (Treg cells): These cells help to suppress the immune response and prevent autoimmune reactions.

Cellular immunity relies on the direct action of these T cells to fight off infections and other threats. They recognize and destroy infected or abnormal cells, preventing the spread of pathogens.

Let me know if you would like to delve deeper into the specific functions of each type of T cell!