What is the primary role of the Major Histocompatibility Complex (MHC)?

The primary role of the Major Histocompatibility Complex (MHC) is to present antigens to T-cells. This function is crucial for the immune response, as T-cells rely on MHC molecules to recognize and respond to foreign antigens, such as those found on pathogens. MHC molecules bind to peptide fragments derived from proteins that are processed within cells and then transport these peptides to the cell surface. T-cells, specifically CD4+ helper T-cells and CD8+ cytotoxic T-cells, interact with these peptide-MHC complexes, leading to T-cell activation. This activation is essential for mounting an effective immune response, including the activation of other immune cells and the destruction of infected or malignant cells.

In contrast, regulating blood pressure, producing antibodies, and facilitating neurotransmission are roles associated with other biological systems and molecules, such as the cardiovascular system, B-cells, and neurons, respectively. Understanding the specific function of MHC in the immune system highlights its critical importance in recognizing and combating infections and diseases.