MHC II molecules

Definition

MHC II molecules are proteins found on the surface of certain immune cells that present antigens to T-helper cells. They play a crucial role in initiating and regulating the adaptive immune response.

5 Must Know Facts For Your Next Test

1. MHC II molecules are primarily expressed on antigen-presenting cells such as dendritic cells, macrophages, and B cells.
2. They present extracellularly derived peptides to CD4+ T-helper cells.
3. The activation of T-helper cells by MHC II is essential for the activation of other immune cells.
4. MHC II molecule presentation leads to cytokine secretion, which helps coordinate the immune response.
5. Genetic diversity in MHC II genes contributes to variability in immune responses among different individuals.

Review Questions

• Which types of cells express MHC II molecules?
• What kind of antigens do MHC II molecules present?
• Why is the interaction between MHC II molecules and CD4+ T-helper cells important?

Related terms

Antigen-Presenting Cells (APCs): Cells that process and present antigens for recognition by certain lymphocytes such as T-cells.

CD4+ T-Helper Cells: A subtype of T-cells that assist other white blood cells in immunologic processes, including maturation of B-cells into plasma and memory B-cells.

Cytokines: Small proteins released by cells that have a specific effect on interactions and communications between cells or on the behavior of cells.