Role of Interleukin-2 in the Immune Response
Endogenous interleukin-2 plays a key role in activating cell-mediated immunity. Its effects include:
- Stimulating proliferation: IL-2 binds to its specific receptors on T lymphocytes, promoting their transition from the resting phase ($G_1$) to the DNA synthesis phase ($S$-phase), leading to active cell division.
- Activating cell-mediated immunity: Under the action of IL-2, T-helper 1 (Th1) cells are stimulated. They begin secreting interferon-gamma (IFN-$\gamma$), which in turn activates cytotoxic T cells and macrophages necessary for destroying damaged and tumor cells.
- Promoting humoral response: IL-2 also affects T-helper 2 (Th2) cells. These cells produce interleukin-4 (IL-4), a mediator that triggers B-lymphocyte proliferation, ultimately leading to antibody production (e.g., IgE).
Mechanism of Action of Aldesleukin
Aldesleukin, as an analog of natural IL-2, replicates its pharmacodynamic effects:
- Binds to specific IL-2 receptors on the surface of immune cells.
- Stimulates the differentiation and active division of T lymphocytes, as well as other IL-2 dependent cell populations.
- Significantly increases the cytotoxic activity of T lymphocytes and natural killer (NK) cells against tumor cells.
- Induces the release of a cascade of other important cytokines, including IFN-$\gamma$, tumor necrosis factor (TNF), and interleukin-1 (IL-1).
Clinical Application
Due to its pronounced ability to activate cytotoxic cells of the immune system, aldesleukin is used in oncology. Its primary indication is the treatment of renal cell carcinoma. The drug mobilizes the body's own resources to fight malignant neoplasms by enhancing tumor recognition and destruction.