Antigénfeldolgozás

Antigénfeldolgozás is a Hungarian term that translates to antigen processing in English. It refers to the complex biological process by which cells break down antigens into smaller fragments, known as peptides, which are then presented on the cell surface. This presentation is crucial for the immune system, particularly for T cells, to recognize and respond to foreign invaders or abnormal self-cells.

The process typically begins when a cell encounters an antigen, such as a bacterium, virus, or even a mutated protein from a cancer cell. Inside the cell, specialized enzyme complexes, like the proteasome, degrade the antigen into peptides. These peptides are then transported into the endoplasmic reticulum, where they associate with MHC (Major Histocompatibility Complex) molecules. There are two main classes of MHC molecules involved: MHC class I and MHC class II. MHC class I molecules primarily present peptides derived from antigens found within the cytoplasm (e.g., viral proteins), while MHC class II molecules present peptides from antigens that have been taken up from the extracellular environment (e.g., bacterial proteins).

Once loaded with peptides, the MHC-peptide complexes are transported to the cell surface. Here, they are recognized by specific T cells. Cytotoxic T cells (CD8+ T cells) recognize peptides presented by MHC class I molecules, triggering the destruction of the infected or abnormal cell. Helper T cells (CD4+ T cells) recognize peptides presented by MHC class II molecules, which helps to orchestrate a broader immune response, including the activation of B cells and other immune cells. Antigénfeldolgozás is therefore a fundamental step in adaptive immunity, ensuring that the body can effectively identify and eliminate threats.