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

  • 2023-02-23

    What leads to severe COVID-19?

    A blood sample is scanned. ©Karin Kaiser/MHH

    The team was able to identify underlying regulators of the malfunction of the innate immune system in COVID-19 patients and confirm that certain already known genetic risk loci play a role in the development of COVID-19. The results have been published in the journal Cell Genomics. First authors on this publication are Dr Valerie Koeken together with Dr Bowen Zhang and Dr…

  • 2022-09-06

    Change with age: As bats mature their immune cells differ

    Simplified 3D representation (UMAP) of Rousettus aegyptiacus blood immune cells, at the single-cell resolution.

    Bat immunology remains mysterious. Many zoonoses originate from wildlife and several emerging, high-impact viruses are bat-borne. Despite harboring lethal viruses little is known about the bat immune system. The group of Anca Dorhoi together with colleagues at the Friedrich-Loeffler-Institut (FLI) in Greifswald and with the group of Emmanuel Saliba at the Helmholtz Institute for…

  • 2021-10-25

    A tiny molecule with a big impact

    Photomicrograph of a Leishmania major infection site showing T cells in red and phagocytes in blue

    "Nitric oxide has two very different effects during an infection: On the one hand, it can directly destroy pathogens that have been taken up by phagocytes. On the other hand, above a certain concentration, it prevents the recruitment of further phagocytes to the site of infection, thus preventing unnecessary tissue damage that would be caused by an excessive immune response," says…

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