Give examples of endocytosis in immune cells and pathogens?

In Immune Cells

1. Phagocytosis: Macrophages and neutrophils perform phagocytosis to engulf and destroy large particles like bacteria, viruses, or cell debris. A macrophage extends pseudopodia around a bacterium to form a phagosome, which then fuses with a lysosome for digestion.

2. Receptor-Mediated Endocytosis: This selective process allows immune cells to take in specific molecules. It helps internalize antigens, which are then processed and presented to other immune cells to trigger an immune response (as described by Study.com).

3. Trogocytosis: In this process, one immune cell "nibbles" or removes surface proteins from another cell. It’s a unique way for immune cells to exchange information and materials directly.

In Pathogens

1. Receptor-Mediated Endocytosis: Many viruses and bacteria exploit this pathway to gain entry into host cells.

• Epstein-Barr Virus (EBV): Attaches to receptors on B lymphocytes to invade and replicate inside them.
• Listeria monocytogenes: Uses a version of endocytosis, possibly caveolin-mediated, to enter host cells and spread within tissues (according to NIH).
• Streptococcus pneumoniae: Tricks host cells by binding to antibody transport receptors, effectively “hitchhiking” into the cell.

2. Caveolin-Mediated Endocytosis: Some bacteria, like Group A Streptococci and Escherichia coli, exploit the host’s caveolin system to enter cells and evade immune detection (as reported by NIH).