Immune System

Endothelial cells are not essentially phagocytic, although they do contribute in the production of mediators of the inflammatory process, particularly acute inflammation and were previously lumped together with the mononuclear phagocyte system in what was known as the reticuloendothelial system (RES).

The granules contain a wide spectrum of microbicidal agents.

The enzyme splits starch and is important for digestion, but not for protection.

The defensins are peptide antibiotics present in the granules in extremely high concentration.

Toll-like receptor 9 recognition of these microbial dinucleotide sequences leads to activation of the NFkB transcription factor.

Neutrophils are chemotactically attracted to the site of inflammation by C5 a and mast cell chemotactic factors such as leukotriene B4.

Perforin inserts into the target cell membrane, thereby facilitating entry of TNF and granzymes into the target cell.

Chondroitin sulphate is a molecule that is found naturally in the body. It has mostly been used to treat joint disorders such as osteoarthritis. This is a cell matrix component.

Derepression of genes in the target cell results in the synthesis of a protein, kinase and an endonuclease.

Many PRR are lectin-like, they recognise exposed microbial sugars.

This is the C3 convertase enzyme generated in the alternative complement pathway and is responsible for splitting the small peptide C3a, leaving C3b as a residue.

These terminal components form a complex, which inserts into the membrane to form a transmembrane ion channel that leads to lysis of the cell.

The ability to ingest bacteria and killing them is a major feature of these professional phagocytic cells. Loss of neutrophils renders the host very susceptible to overwhelming infection.

Activation of mast cells releases chemotactic factors for neutrophils and vasoactive mediators such as histamine.

They act in a sequential proteolytic cascade, which gives tremendous amplification of the response.