Mechanisms of Innate Immunity&

Antigen Presentation

Huan-Yao Lei, Ph.D.

Department of Microbiology & Immunology

College of Medicine

National Cheng Kung University

Summary of Chapter 6 Mechanisms of innate immunity • Innate immune responses do not depend on immune recognitio

n by lymphocytes • The body's responses to damage include inflammation, phagoc

ytosis, and clearance of debris and pathogens, and remodeling and regeneration of tissues.

• The phased arrival of leukocytes in inflammation depends on chemokines and adhesion molecules expressed on the endothelium.

• Leukocyte migration to lymphoid tissues is also controlled by chemokines.

• Plasma enzyme systems modulate inflammation and tissue remodeling.

• Pathogen-associated molecular patterns (PAMPs) are distinctive biological macromolecules that can be recognized by the innate immune system.

• Microbicidal proteins are part of the innate immune system.

Summary of Chapter 7 Antigen presentation • T cells recognize peptide fragments that have been processed and beco

me bound to major histocompatibility complex (MHC) class I or II molecules.

• MHC class I molecules associate with endogenously synthesized peptides, binding to peptides produced by degradation of the cells' internal molecules.

• MHC class II molecules bind to peptides produced following the breakdown of proteins that the cell has endocytosed.

• Cross-presentation allows APCs to acquire antigens from infected cells. • Co-stimulatory molecules are essential for T cell activation. • CD4 binds to MHC class II and CD8 to MHC class I molecules. • The highly ordered area of contact between the T cell and APC is an imm

unological synapse. • T cell activation induces enzyme cascades, leading to the production of in

terleukin-2 (IL-2) and the high-affinity IL-2 receptor on the T cell. • Antigen presentation affects the subsequent course of an immune respon

se.