The Immune system - Bulwark against Disease

Each second of our lives, we are being attacked by numerous pathogens such as Viruses and bacteria. Our immune system is constantly busy fighting these invaders. Without the innate defence system of our body, which consists of various types of cells and molecules, we would be defenceless against these attacks.

The immune system makes use of two different mechanisms in its fight against pathogens: the non-specific and the specific Immune defence.

First line of defence: Non-specific immune defence

When pathogens invade the body, for example by way of a wound, the non-specific immune system reacts first. Anchored deeply in the genome, this first line of defence ensures that pathogens can be fought and disposed of within a few minutes.

Immune System

When the body recognises foreign elements, it fights them by means of various defence cells and plasma proteins circulating in the bloodstream. These components, both cellular and humoral - which means present in the blood - can destroy the cell walls of the invaders or activate scavenger cells, which then "devour" the pathogens. Which cells and proteins participate specifically depends mainly on the type and site of the Infection because pathogens are very diverse. Researchers presume that 90 percent of all infections are successively controlled by the innate Immune defence.

Specific immune defence - A specific match for the pathogen 

If the pathogen successfully overcomes the first line of defence and spreads, the specific Immune defence gets involved. This system adapts individually to certain pathogens, matches them and develops a corresponding immune response. This is also called adaptive immune response. It gets involved when the foreign elements invade into the lymphatic tissue, a part of the lymphatic system, which pervades the entire body. This is where the Pathogens encounter B cells, which recognise the features of the pathogen by means of receptors. Based on these features, also called Antigens, Antibodies can be produced. By means of T-cells the B cells differentiate into more specialised Plasma cells that produce large amounts of highly specific Antibody and spread across the entire body.

The Antibodies prevent the pathogen from spreading further and limit its mobility and support the scavenger cells by "marking" the germs. These measures allow the Infection to be overcome.

Smart pathogens

However, despite this sophisticated defence mechanism, humans do still get ill. Mainly because pathogens are smart, adaptable and mutable. There are still many unanswered questions that are being addressed by researchers throughout the world.

Researchers at the HZI also investigate the interaction between Immune defence and pathogens. For these studies, the researchers develop new models that are adapted to the human immune system, and then study the mechanisms of immune response. They also look at the aging of the immune system and develop adjuvant substances to improve the efficacy of vaccines. The successes achieved in the past highlight how important it is for infection research to understand the complex mechanisms of the immune system. For this reason, immune response and immune interventions have moved into the focus of the HZI and are one of the three key topics at the centre.


Research at HZI

  • 2019-10-29

    Super-antibody strategy for universal vaccines


    Broadly neutralising antibodies attack multiple strains of a pathogen, neutralise its effect and thus support the immune system, and have already been identified for HIV or influenza viruses, for example. Their special feature is that they bind to conserved molecular structures of the viruses that do not change much, while the pathogen continues to mutate in the organism. This makes…

  • 2019-03-21

    Important mechanism of antigen presentation in immune system guard cells deciphered


    The immune system is a highly efficient surveillance system that immediately takes action when, somewhere in the body, a cell signals that it is infected. A key mechanism of immune defence is based on cells carrying special receptors on their surfaces, which can display foreign protein fragments. If a foreign protein appears on the cell surface in the human leukocyte antigen (HLA)…

  • 2016-02-19

    Flexibility, rather than perfection, helps in the fight against pathogens

    Mesenteric lymph node of a Confetti mouse infected with Friend retrovirus. The clusters of colored cells are germinal centers showing different levels of color dominance.

    When a foreign substance invades a body, the body produces antibodies that recognise and fight the intruder by means of antibodies that bind to a specific portion of the intruder - the antigen. Memory cells are then formed in the course of the defence reaction. These cells make sure that the body can respond more quickly and more strongly to any recurring attack of the same pathogen.…

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