Antigenfeldolgozás

Antigenfeldolgozás, a Hungarian term, translates to "antigen processing" in English. It is a fundamental biological process crucial for the adaptive immune system. This process involves breaking down foreign proteins, known as antigens, into smaller fragments. These fragments are then presented on the surface of cells, primarily by major histocompatibility complex (MHC) molecules. This presentation allows T lymphocytes, a key type of immune cell, to recognize and respond to the foreign invaders.

There are two main pathways for antigen processing. The endogenous pathway deals with antigens produced within the cell, such as viral proteins or abnormal cellular proteins. These antigens are degraded by the proteasome and then transported to the endoplasmic reticulum, where they are loaded onto MHC class I molecules. These MHC class I-antigen complexes are then displayed on the cell surface, signaling cytotoxic T lymphocytes to eliminate the infected or cancerous cell.

The exogenous pathway handles antigens that originate from outside the cell, such as bacteria or allergens. These antigens are taken into the cell through processes like phagocytosis or endocytosis. Within specialized compartments, they are broken down by enzymes and then loaded onto MHC class II molecules. These MHC class II-antigen complexes are presented on the surface of antigen-presenting cells (APCs), such as macrophages and dendritic cells, and are recognized by helper T lymphocytes, which then orchestrate a broader immune response. Effective antigen processing is therefore essential for initiating and guiding adaptive immunity.