Innate Immunity – Acquired Immunity

T cells (shown in red) interacting with dendritic cells
© HZI/Manfred Rhode
T cells (shown in red) interacting with dendritic cells.

The human immune system exists of a huge number of different cells with different functions. They occur in the blood as „white blood cells“. A part of them recognises germs and illness causes as foreign structures in the body and operates early in the course of an infection. These cells which form the so-called „innate immune system“ are constantly active.

The cells that form the "innate immune system“ to make sure that only rarely will a virus or bacterium we encounter in our daily lives actually make us sick. This branch of the immune system is called innate because the cells it is made up of are present in the body and ready for action by the time we are born.

Two types of cells

Two cell types in particular play a key role in innate immunity: Natural killer (NK) cells and dendritic cells. The job of NK cells is to recognise and kill off virally infected cells or tumor cells early on. NK cells constitute the immune system's first line of defence against an infection. The star-shaped, highly branched dendritic cells' job is to be on the lookout for intruders in the skin and in mucous membranes, and, upon encounter, to engulf and digest them. Dendritic cells travel to the nearest lymph node by way of lymphatic vessels. The lymph nodes represent an important interface between innate immunity and its counterpart, acquired immunity. Contact with dendritic cells and the load they carry, which is made up of chopped up bits of pathogens called antigens, activates a type of white blood cell called a T cell.

B cell binds to an antigen-specific T cell
© HZI
A B cell binds to an antigen-specific T cell to present its antigen. The spaghetti-like structures represent collagen fibers.

T cells are by far the most abundant cell type in what is known as our acquired immunity. Every single one of these cells is capable of recognizing highly specific protein molecules, which activate them, triggering their division. The genetically identical progeny then spread via the bloodstream in search of infected cells that present recognition proteins on their surfaces. Some of the T cells eliminate infected cells while others help the rest of the immune cells perform their jobs. B cells are rather similar in their specificity. They too recognise bits of pathogens, which prompts them to make antibodies that are central in the fight against germs and which can help protect us from subsequent re-infection. This particular property of B cells is exploited in vaccines.

(jsg)

Involved research groups

News on the topic

Lina Herhaus (top left), Martin Jahn (top right), Milan Gerovac (bottom left) and Natalia Torow (bottom right) are MICROSTAR junior research group leaders at HZI.
News

Four new junior research groups at the Helmholtz Centre for Infection Research

At the Helmholtz Centre for Infection Research (HZI) in Braunschweig, four young scientists will start their work in late summer and fall 2024 to investigate resilience mechanisms of microbes and humans. As part of the MICROSTAR (Microbial Stargazing) project, Lina Herhaus, Martin Jahn, Milan Gerovac and Natalia Torow were recruited in a highly competitive process. Over an initial period of five years, their research groups will investigate cutting edge issues related to signal transmission in infections, the intestinal microbiome, bacteriophages and the development of immunity.
17.07.2024
Arm with erythema due to Borrelia infection
News

Lyme disease: Probability of developing the disease is genetically predisposed

Lyme disease is the most common disease transmitted by tick bites in Germany. Whether a particular genetic predisposition plays a role in the development of the disease and which immunological processes in the body are involved is not yet sufficiently understood. A research team from the Centre for Individualised Infection Medicine (CiiM), a joint institution of the Helmholtz Centre for Infection Research (HZI) and Hannover Medical School (MHH), has now discovered a responsible gene variant and the immune parameters involved in cooperation with Radboud University Hospital (Radboundumc; Radboud Universitair Medisch Centrum) and Amsterdam UMC (both in the Netherlands). The researchers have published their findings in two studies. These have been published in the journal Nature Communications and BMC Infectious Diseases.
13.05.2024
Vero6 cells (renal epithelial cells) infected with SARS-CoV-2
News

Diversity is the key

The so-called B cells are part of the immune system's memory. Their memories of previous infections or vaccinations provide the template for antibodies that have a protective effect the next time they come into contact with a pathogen. Researchers at TWINCORE, Centre for Clinical and Experimental Infection Research, have now been able to show that the combination of infection and subsequent vaccination in the case of the SARS-CoV-2 coronavirus even protects against future variants of the virus by the memory cells virtually predicting the future. The team describes how this works in the European Journal of Immunology. The TWINCORE is a joint institution of the Helmholtz Centre for Infection Research (HZI) in Braunschweig and Hannover Medical School (MHH).
25.04.2024
Martina Palatella (left) and Margherita Pevere in the laboratory of the department “Experimental Immunology”.
News

Margherita Pevere: Immune cells become biological art objects

It is widely known that the cells of the human immune system are natural works of art that protect us from serious diseases on a daily basis. Now they are also part of an art project at the Helmholtz Centre for Infection Research (HZI) in Braunschweig: The international artist Margherita Pevere used the HZI laboratories to examine her own immune cells and will create a work of art from the results. Pevere is supported in her work by Martina Palatella, a doctoral researcher in the HZI department “Experimental Immunology” headed by Prof Jochen Hühn.
15.02.2024
Illustration Virus
News

A virus lurking in the connective tissue

It was previously believed that herpesviruses use certain body cells to replicate and other body cells to remain dormant, that is to remain inactive for a longer period of time. This dogma is now being questioned using the example of cytomegalovirus (CMV), a herpesvirus from the beta-herpesvirus subfamily, which can be fatal in immunocompromised transplant recipients. In a new study, scientists from the “Viral Immunology” department at the Helmholtz Centre for Infection Research (HZI) in Braunschweig have discovered that certain connective tissue cells (fibroblasts) are not only used by CMV for replication, as previously assumed. Apparently, CMV can also remain latent in the fibroblasts. The prevailing picture of an either/or - either the CMV uses a certain type of body cell for proliferation, or it remains in an inactive state there - is therefore no longer tenable. A second paradigm shift suggested by the study is the regulation of the CMV latency in cells: Apparently, the virus controls the use of fibroblasts as sites of latent or active infection not only via factors present in the cell, but also via an interaction with the immune system. The results were published in the renowned journal Nature Communications.
30.05.2023
Blood samples
News

What leads to severe COVID-19?

Infection with SARS-CoV-2 leads to severe disease in some people, whereas others do not get ill or only experience mild disease. What causes these differences is not fully understood. It is already known that an overactive innate immune system is causing severe COVID-19 disease, but it is unclear how this is regulated. A team led by Prof Yang Li, Director at the Centre for Individualised Infection Medicine (CiiM) and head of department “Computational Biology for Individualised Medicine” at the Helmholtz Centre for Infection Research (HZI), has come a step closer to answering this question. The researchers addressed the question to what extent the course of disease is genetically or epigenetically regulated. The CiiM is a joint initiative by the HZI and Hannover Medical School (MHH). In addition to Li, the team included other scientists from the HZI and the RESIST cluster of excellence.
23.02.2023
Vereinfachte 3D-Darstellung von Immunzellen
News

Change with age: As bats mature their immune cells differ

A team of researchers led by Anca Dorhoi at the Friedrich-Loeffler-Institut (FLI) and Emmanuel Saliba at the Helmholtz Institute for RNA-based Infection Research (HIRI), has elucidated age-dependent variations in cellular immunity in Rousettus aegyptiacus, known as the Egyptian fruit bat, a natural reservoir for filoviruses such as Marburg Virus. Using cutting-edge single-cell technologies, they mapped the bat blood with unprecedented resolution. The scientists unveiled that progression to adult age enriches for T lymphocytes and putative regulatory myeloid cells at expenses of B cells. These findings offer deeper insights into the immune system of an important wildlife reservoir species and are now published in Cell Reports.
06.09.2022
Mikroskopieaufnahme einer Infektionsstelle von Leishmania major in der Haut
News

A tiny molecule with a big impact

Nitric oxide (NO) occurs naturally in the human body as a messenger substance. It is considered an all-rounder, as it performs numerous important regulatory functions, including immune defense against pathogens. The exact mode of action of this molecule has now been uncovered by immunologist Prof Andreas Müller from the Institute of Molecular and Clinical Immunology at the University Medical Center Magdeburg together with scientists from the Helmholtz Centre for Infection Research (HZI) in Braunschweig. The findings are crucial for the development of new therapeutic approaches for the treatment of infectious diseases, but also of diseases caused by excessive inflammation. The results were published in the renowned journal "Immunity".
25.10.2021
Rasterelektronenmikroskopische Aufnahme einer menschlichen B-Zelle
News

Vaccination success without B cells

Immunosuppressed patients often cannot build up good protection after a vaccination because the necessary cells of the immune system function less well or are not present at all. This has been studied especially in the drug therapy of rheumatoid arthritis. Scientists from TWINCORE and the Hannover Medical School (MHH) have now published in the journal Annals of the Rheumatic Diseases the circumstances under which this group of people can nevertheless be successfully vaccinated. Based on their data, they recommend a promising strategy for the COVID-19 vaccination of rheumatism patients who are treated with the drug Rituximab. The TWINCORE-Centre for Experimental and Clinical Infection Research is a joint institution of the MHH and the Helmholtz Centre for Infection Research (HZI) in Braunschweig.
15.07.2021
Vero6-Zellen infiziert mit SARS-CoV-2
News

Helmholtz researches holistic solutions for pandemic response

How can we apply the knowledge we have gained so far to better overcome the current crisis and prevent another pandemic in future? Helmholtz aims to find answers to these questions with two new, interdisciplinary collaborative projects. In addition to the holistic approach, the focus is also on quickly implementing the results into practice.
20.05.2021
Illustration
News

How well are we protected six months after infection or vaccination?

After exposure to a virus through infection or vaccination, the body activates a number of cells and mechanisms that can provide targeted defense against the pathogen. For the global containment of the SARS-CoV-2 pandemic, the question of how long this protection lasts is an important factor. Prof Carlos Guzmán, vaccine researcher at the Helmholtz Centre for Infection Research (HZI) in Braunschweig, Germany, summarizes what is known about long-term immunity to SARS-CoV-2 and what difference it makes whether immunity is acquired through vaccination or infection.
08.04.2021
Elektronenmikroskopische Aufnahme einer T-Zelle
News

‘Big data’ training network for T-cell researchers at the HZI

As part of the adaptive immune system, T cells are involved in the defence against pathogens. However, if they recognise healthy, self-structures instead of invading pathogens, autoimmune diseases can result. It is still insufficiently understood which factors are responsible for the dysregulation of the T cells. A new EU-funded programme for young researchers, coordinated by Prof. Jochen Hühn at the Helmholtz Centre for Infection Research (HZI) in Braunschweig, aims to study tissue-resident T cells in more detail. Within the framework of the training network, 15 doctoral students will be trained at academic and non-academic institutions in ten European countries.
01.03.2021
Mikroskopische Aufnahme einer Lungengewebsprobe mit einer aktiven Zytomegalie-Infektion. Charakteristisch sind vergrößerte Lungenzellen mit Einschluss im Zellkern.
News

Protection against the immune system

Virologists at the Helmholtz Centre for Infection Research (HZI) in Braunschweig have identified a crucial survival factor in viruses. Their results were recently published in the scientific journal Proceedings of the National Academy of Sciences and could lead to a paradigm shift in virus immunology.
10.06.2020
Niedersächsischer Ministerpräsident Stephan Weil und Minister Björn Thümler besuchen das Helmholtz-Zentrum für Infektionsforschung.
News

Prime Minister of Lower Saxony Stephan Weil and Minister Björn Thümler visit the Helmholtz Centre for Infection Research

A distinguished visitor to the Helmholtz Centre for Infection Research: The Prime Minister of Lower Saxony Stephan Weil and Lower Saxony’s Minister of Science and Culture Björn Thümler visited the Helmholtz Centre for Infection Research (HZI) in Braunschweig today. The focus of the visit was on current challenges and innovative solutions, especially in the fight against SARS-CoV-2 and the future development of infection research in Lower Saxony.
08.05.2020
Der Virologe Luka Cicin-Sain erforscht SARS-CoV-2-neutralisierende Antikörper, die von der Technischen Universität Braunschweig und YUMAB isoliert wurden.
News

Hope for antibody therapy against Covid-19

Neutralizing antibodies are the interceptors of our immune system. They bind precisely to pathogens and prevent them from entering our cells. After an infection, the immune system needs about two weeks to produce mature antibodies. In severe cases of Covid-19, the body's immune reaction often comes too late for the patient. One option for acute treatment would therefore be to administer antibodies to the patients that are immediately effective. Recent results of the CORAT Consortia, especially from the Helmholtz Centre for Infection Research (HZI) in cooperation with the Technische Universität Braunschweig and the company YUMAB, have led to a breakthrough in the development of fully human antibodies for immune therapies.
07.05.2020
How susceptible are small children to the new coronavirus? Tests on 500 LöwenKIDS are underway.
News

LoewenKIDS help scientists in a COVID-19 study

Currently, little is known about children and their susceptibility to the new coronavirus. It has been observed that young children have rarely presented with COVID-19 up to now. No specific investigations have been conducted as to how many children have already contracted the virus and overcome the infection without any remarkable symptoms. In a DZIF project, scientists now intend to investigate this with the help of “LoewenKIDS”.
28.04.2020
Abbildung eines Corona-Virus
News

Helmholtz position paper on the epidemiological situation

Researchers from the Helmholtz Centre for Infection Research (HZI) in Braunschweig and the Forschungszentrum Jülich (FZJ) are modelling the further course of the epidemic, taking into account various scenarios for relaxing the ban on contact and making recommendations.
14.04.2020
Blutproben
News

Population study investigates immunity to Covid-19

After an infection with the coronavirus SARS-CoV-2, patients have antibodies against the pathogen in their blood. These are retained over a long period of time and are an indication for a past infection. It is assumed that patients who have recovered from the Covid-19 disease cannot be re-infected with SARS-CoV-2. To date, no data are available on whether there is an unrecognized Covid-19 immunity in the population beyond the SARS-CoV-2 infections recorded. The Helmholtz Centre for Infection Research (HZI) in Braunschweig is now coordinating a study to investigate this question. Anonymous sera from more than 100,000 donors will be analyzed in the population study. The blood will be regularly tested for antibodies against the Covid-19 pathogen. The study will provide a more accurate picture of immunity and pandemic development.
27.03.2020
Illustration des Aufbaus eines Klasse II CRISPR-Systems
News

Large repertoire of new gene editors

The CRISPR-Cas technology can be used to precisely edit DNA. Originally, it is a viral defense mechanism of bacteria. The CRISPR-Cas systems currently in use in biotechnology are classified as class II. They are characterized by a single Cas (CRISPR-associated) protein that is sufficient for the activity of the system. In contrast, class I CRISPR-Cas systems require the interaction of multiple proteins. Researchers from Duke University (USA), North Carolina State University (USA), and the Helmholtz Institute for RNA-based Infection Research (HIRI) in Würzburg have, for the first time, used class I-systems to regulate gene expression in human cells. The HIRI is a joint institution of the Helmholtz Centre for Infection Research (HZI) in Braunschweig and the Julius Maximilian University of Würzburg. The study considerably expands the number of biotechnologically usable CRISPR-Cas systems for human therapeutics. It was published in the journal Nature Biotechnology.
22.11.2019
DNA-Abschnitte in einer Zelle
News

A new tool to direct CRISPR to multiple targets

CRISPR-Cas-based gene editing has been used for a large variety of applications. The system requires guide RNAs, whose sequence specifically determines the site where DNA or RNA modification occurs. Scientists at the Helmholtz Institute for RNA-based Infection Research (HIRI) describe a powerful means to assemble CRISPR arrays, part of CRISPR-Cas systems that encode multiple guida RNAs. Assembled CRISPR arrays can then be used to direct the gene editing machine to multiple parallel targets. The HIRI is a joint institution of the Helmholtz Centre for Infection Research (HZI) in Braunschweig and the Julius Maximilian University of Würzburg. The novel tool CRATES enabled Prof Chase Beisel and his research group “Synthetic Biology of RNA” to gain new insights into the biology of CRISPR-Cas systems.
15.11.2019