* T lymphocytes (T cells): These are the primary cells responsible for cell-mediated immunity. They are further divided into various subsets, each with distinct roles:
* Cytotoxic T lymphocytes (CTLs or CD8+ T cells): These cells directly kill infected or cancerous cells by releasing cytotoxic substances like perforin and granzyme.
* Helper T lymphocytes (Th cells or CD4+ T cells): These cells regulate the immune response by secreting cytokines that activate other immune cells, including CTLs, B cells, and macrophages. They are further divided into Th1, Th2, and Th17 cells, each with specific functions.
* Memory T cells: These are long-lived T cells that "remember" previous encounters with specific antigens. They can quickly mount an immune response upon re-exposure to the same antigen.
* Regulatory T cells (Tregs): These cells help suppress the immune response to prevent autoimmune reactions.
* Natural Killer (NK) cells: These cells are part of the innate immune system, but they play a crucial role in cell-mediated immunity. NK cells can directly kill infected or cancerous cells without prior sensitization to a specific antigen.
* Macrophages: These phagocytic cells are important in engulfing and destroying pathogens. They also present antigens to T cells, which helps activate the adaptive immune response.
* Dendritic cells: These cells are antigen-presenting cells (APCs) that capture antigens and present them to T cells. They are crucial in initiating the adaptive immune response.
It's important to note that all these cells work together in a complex and coordinated manner to ensure effective cell-mediated immunity.
