Question

Some immune system cells produce a significant amount of a protein called histamine, which they need to transport outside the cell to carry out its functions in the body. These cells face a challenge: histamine is a large molecule that cannot pass through the cell membrane solely through physical means. While we haven't discussed immune system cells or histamine in detail yet, you are aware of three potential strategies these cells might employ to control the movement of histamine. Describe how the cell could utilize each of these three options to transport histamine outside the cell. For each strategy, outline the initial conditions, the requirements, the process, and the ultimate outcome.

Answer 1

Immune cells can transport histamine outside the cell through receptor-mediated endocytosis, exocytosis, and phagocytosis.

Step-by-step explanation:

Immune system cells have three strategies to transport histamine outside the cell:

1. Receptor-mediated endocytosis: Extracellular antigens are brought into the cell through this process. The vesicle containing the antigens fuses with vesicles from the Golgi complex, which contain pre-formed MHC class II molecules. The new vesicle then makes its way to the cell surface.
2. Exocytosis: Immune cells produce and secrete large amounts of histamine through this process. The histamine is packaged into membrane-bound vesicles within the cell. When the vesicle membrane fuses with the cell membrane, the vesicle releases its contents into the interstitial fluid.
3. Phagocytosis: Large particles, such as macromolecules, can be engulfed by cells through this process. Immune cells like neutrophils remove pathogens by engulfing them through phagocytosis.