F: IMMUNE SYSTEM RECOGNITION
BIOCHEMISTRY - DR. JAKUBOWSKI
Last Updated: 03/14/13
Learning Goals/Objectives for Chapter 5E: After class and this reading, students will be able to
The adaptive immune response must be activated by cells of the innate immune system. These cells must recognize viruses and living cells like bacteria, fungi, and protozoans like amoebas. There are often common structural features in these different classes of cells. The cells of the innate system (dendritic cells, macrophages, eosinophils, etc) have receptors (Toll-like Receptors 1-10 or TLRs) that recognize the common pathogen associated molecular patterns (PAMPs) , which leads to binding, engulfment, signal transduction, maturation (differentiation), antigen presentation, and cytokine/chemokine release from these cells. Take for example dendritic cells, which reside in the peripheral tissues and act as sentinels. They can bind PAMPs which include:
Bacterial and viral nucleic acids are recognized by intracellular TLRs in the cell after the they been taken up into the cells by endocytosis. Dendritic cells phagocytize microbial and host cells killed through programmed cell death (apoptosis). In the process of maturation, surface protein expression is altered, allowing the cells to leave the peripheral tissue and migrate to the lymph nodes where they activate T cells through the antigen presentation methods described above. They also control lymphocyte movement through release of chemokines. The very large figure below shows the processes involved in recognition of PAMPs by TLRs of innate immune system cells.
A model of dsRNA interacting with the ligand binding domain of TLR3 is shown below.
Return to Chapter 5E: Immune System Recognition
Return to Biochemistry Online Table of Contents
Archived version of full Chapter 5F: Immune System Recognition