Questions tagged [immune-system]

This tag is for general questions related directly or indirectly to the vertebrate immune system, but are not questions directly related to Immunology, the discipline of the study of the immune system.

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Can macrophages phagocytose viruses directly?

I've been reading that Macrophages, members of the innate immune system, can actively track bacteria and protozoa to devour and destroy them. In the same way, can macrophages devour free viruses, in ...
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Why are lymph nodes located where they are? [closed]

According to the National Cancer Institute, a subdivision of the National Institutes of Health, clusters of lymph nodes are found in the neck, underarm, chest, abdomen, and groin. Why are lymph nodes ...
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What's the exact mechanism of oral tolerance? [closed]

I have mainly two matters of confusion need to be clarified. First question: The immune system does not necessarily kill everything hat has PAMPS, the bacteria living in the gut, have PAMPS (Pathogen-...
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how do phagocytes receptors work now and in the past?

As we know, phagocytes have receptors on their cell that are used to detect pathogens which they bind to and engulf them. That seems easy. Though, I'm trying to wrap my head around the fact how the ...
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How does the body avoid making an immune response to self-antigens?

The body contains antigen-detecting and presenting cells (APCs) including leukocytes and cytokines each having their characteristic HLA genes consisting of different recognition sites that detect the ...
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What are monocytes with vacoules called?

I've heard that monocytes sometimes appear with vacuoles. Do monocytes with a vacuole have a name? If so, do monocytes without a vacuole have a name as well?
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Exhaustion of 'memory' CD8 T cells

I've been reading literature on the exhaustion of cytotoxic CD8 T cells. In many of the papers I read, the authors aim to delineate molecular mechanisms that differ between exhausted and memory ...
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CDRs and antigen-binding sites [duplicate]

Are complementarity determining regions (CDRs) not the same thing as antigen-binding sites? If not, what is the difference? An old exam question states: "Clarify how CDRs are related to the ...
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Role of the CD3 proteins and ζ chain

Could someone please explain which of the following is correct and why? The role of the CD3 proteins and ζ chain on the surface of the cell is to: a) transduce signals to the interior of the T cell b)...
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What is the difference between a macrophage and dendritic cell?

I am aware that both these cells (monocytes) are phagocytes and are able to present antigens upon their own Class II - MHC integral proteins. Other than their difference in structure (size and shape), ...
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T-Cell Receptor Receptor-Associated Immune Receptor Activation Motifs (ITAMs) Inconsistency

In reading the information associated with the cytoplasmic machinery of the T-Cell Receptor (TCR), the one tyrosine motif that is consistently mentioned is the receptor-associated immune receptor ...
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Are individual auto-reactive 'lymphocytes' or auto-reactive 'clones' generated in the central lymphoid organs?

Clonal deletion is a well-known mechanism of immune central tolerance. But individual lymphocytes or lymphocyte clones are subjected to apoptosis? If clones, then what is the reason to allow mitosis ...
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If RBCs don't have MHC I, why don't NK cells kill them?

As mentioned in textbooks, All nucleated cells have MHC class I molecules on the cell surface. RBCs have no nucleus, therefore no MHC I NK cells kill cells with deficiency in MHC I presentation Then ...
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Abilities used to survive against natural enemies: directional selection or frequency-dependent selection?

Regarding abilities used to survive predators and parasites, are they subjected more to directional selection or frequency-dependent selection? It's usually that host-parasite coevolution is ...
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Antigen transfer from baby to mother

When considering immunity in babies, the main mechanism that supports their undeveloped immune system is the transfer of antibodies from mother to baby via breastfeeding. Case #1: both baby and mother ...
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Why there is swelling when skin doesn't break visibly? [closed]

I had read that swelling occurs as result of blood vessels pouring watery fluid in the affected area to help in fighting the incoming pathogens, when we our skin is cut open. However sometimes like ...
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What is the optimal temperature for Omicron to thrive in?

I have always been under the impression that when sick, you should let a fever run its course. The accepted answer to the question Why do people take drugs to lower a fever? seems to provide some ...
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What is the significance of an adjuvant to traffic vaccine antigen directly to draining lymph nodes without diffusing into the systemic circulation?

I found the following sentence in the this paper- Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152: a double-blind, randomised, phase 1 trial An imidazoquinoline molecule, which ...
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Is the response to a vaccine correlated with the reaction to the disease?

I was wondering if the response to a vaccine correlates with the reaction to the disease. For example, if someone had a strong reaction to a vaccine, this person would also have had a severe course of ...
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How much of TLR 7 agonist is safe for human beings, as it is both linked to development of autoimmune diseases but is also used as Vaccine adjuvant?

This question is motivated by the fact that TLR 7 agonists have been linked to development and acceleration of Lupus-like disease both in animals and human beings. But at the same time, TLR 7 agonist ...
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Why are scientists saying that the Omicron COVID-19 variant is a reason to get a booster?

I was watching Vox’s video, Big questions about the Covid booster shot, answered, which references the New York Times article Omicron Prompts Swift Reconsideration of Boosters Among Scientists. In ...
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What is the definiton of repertoire shift in B cells?

I am new to biology and trying to understand this term. Couldn't find a comprehensive defintion. Thank you
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What is the upper limit for 'active' vaccinations

As far as I know the effect of vaccines is caused mainly by creating Memory Cells specific to a single pathogen. As there is obviously a lower limit of memory cells needed for immunity ( at least one),...
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What animal has the strongest immune system?

I'm wondering what animal has the strongest immune system. It can be defined as the most evolved immune system or the immune system that can eliminate or tolerate most number of (different) viruses/...
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Viral vector vaccines - why doesn't the viral vector get attacked by the innate immune system?

I've been looking at how the Astrazeneca Covid-19 vaccine works: A chimpanzee adenovirus (the viral vector) is injected into the patient. After entering a cell, the viral DNA is deposited in the host ...
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Why do the mRNA vaccines for COVID need special lipids?

I've read that the Pfizer mRNA vaccine is delivered to the cell by encapsulating the fragile mRNA into a lipid nanoparticle. However, the lipid has to be PEGylated in order to avoid immunogenecity. ...
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Are autoantibodies against intracellular proteins "functional"?

Autoantibodies against intracellular proteins have been detected in some autoimmune diseases (For example, TRIM21 in Sjögren's syndrome and NALP5 in Autoimmune Polyendocrine Syndrome Type 1). My ...
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Do COVID-19 vaccines produce more spike protein than natural infection?

The SARS-CoV-2 spike protein has been shown to be harmful on its own. However, a news article quoted an "expert" as saying The spike protein components of the vaccine are not produced in ...
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7 votes
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Is the covid-19 vaccine-induced copy of the protein spike also damaging cells?

In recent scientific articles, it has been discovered how the spike protein not only is a respiratory disease but also damages blood vessels cells directly, and is connected with higher risk of ...
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How do APCs find their specific T-cells in the lymph nodes?

My understanding is that when an APC (more specifically a dendritic cell) encounters an antigen in the periphery, it ingests it and presents it on its surface. It then migrates to lymph nodes to ...
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Is covid vaccine helpful for a covid patient?

I am not a biology student and this question came in my mind out of nowhere. I read somewhere that the vaccines contain some denatured or almost dead corona viruses and when these are injected in our ...
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Does stronger reaction to vaccine (fever, days of nausea) mean that an immune system would have reacted the same to the virus?

I have heard that the real danger of Covid-19 is the strong immune response. Is it more likely that a person's immune system would have reacted dangerously to the virus?
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What makes a bacterium move away from a neutrophil cell?

In this video we see a bacterium seemingly moving away from the neutrophil that is chasing it. What mechanism makes it "want" to avoid the neutrophil? It doesn't seem to mind being around ...
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What differentiates bound antibodies from unbound ones?

When an antibody is bound to an antigen, it can then stimulate a FcR receptor on a phagocyte etc. to respond to the threat. What stops 'free' antibodies from spuriously activating an immune response? ...
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Why is graft-vs-host so selective against phylogenetically close cells?

Is there a well established explanation for the phenomena that graft-vs-host is so much more selective against phylogenetically close cells? See historically significant references below, "This ...
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Which landmark paper first described the differentiation of T-cells?

T-cells are distinguished from B cells in part by their locus of differentiation/maturation (thymus). This is textbook knowledge, but I was wondering which particular person or people were responsible ...
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How does lactate produced in the intestines get transported to the rest of the body?

Some gut bacteria known as lactic acid bacteria(LAB) are known to produce lactate in the intestines and they confer beneficial effects such as enhancement of the immune system, but I assume not all of ...
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What happens if a circulating naive B cell is met with a polysaccharide/lipid antigen?

These antigens should provoke a T-independent response, so will they differentiate then and there to form short-lived plasma cells? Or do they have to go to lymphoid tissue, enter a B follicle, and ...
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Spike protein production by mRNA vaccines?

I am trying to understand the spike protein production mechanism of the mRNA vaccines, and during my research I learned that the mRNA (Moderna, mRNA-1273) vaccines hijack the cell machinery to produce ...
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Why can't C1r cleave C4 proteins?

I am researching the complement system, and have ran into something I'm not really sure about. In the past, the C1r2s2 complex was thought to be an 8-like structure tucked inside C1q's collagenous ...
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How do injected purified anti-D antibodies prevent the natural production of antibodies in order to prevent Hemolytic Disease of the Newborn?

Treatments involving Anti-D antibodies are given to pregnant women carrying Rh+ fetuses when the mother has an Rh- blood type in order to prevent Hemolytic Disease of the Newborn during the 2nd ...
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Why is the food we consume right from birth not immunogenic to elicit an immune response? [closed]

Excluding the hypersensitive reactions which are individual specific, how is food we consume considered safe by the immune system?
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Howthe body differentiate between foreign and native protein? How does it know when to create an immune response? [duplicate]

How the body differentiate between a foreign and a native protein? Suppose there is a bacteria, it has lot's protein on its membrane, with specific structures. How does our body know it's the foreign ...
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Auto-immune problems if immature B-cells released if bone marrow bone is fractured?

A fracture of a bone containing bone marrow with B-cells not yet taught to not recognize self-antigen, if the bone is fractured, can those cells get released and cause problems?
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Can you still contract a disease after being vaccinated and be able to spread it?

I assume I know the answer to this already but wanted to confirm before I respond to someone that appears to be arguing that vaccines don't make you immune (they only stop your symptoms?) - but you ...
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Does immunity to CRISPR proteins limit their effectiveness?

The use of crisper-cas systems is currently applied to cells cultivated in vitro. As control of the ‘off target’ effects of Crispr improves and Crispr is used in vivo, why won’t the immune system ...
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How T-Cell recognizes a cell infected by a virus?

According to few articles I read (like BBC about The people with hidden immunity against Covid-19 ): starting out about four or five days after infection, you begin to see T cells getting activated, ...
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What is the mechanism responsible for long-lasting detectable antibody titers?

As I understand, when naive B cell encounters antigen matching its receptors and is activated by a T helper cell, it can either differentiate into 4 plasma cells, produce a lot of antibodies and ...
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How can I detect which antibody is produced by the B cell?

In the primary immune response, IgM is produced (in addition to IgD ). In the secondary immune response, various types of antibodies are produced. So how do I detect which antibody a B cell is ...
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About how many covid-19 virus particles is required in the human body before infection and sickness follows?

Our immune systems are often able to destroy germs and virus particles. About how many of them does it take to make a 70 year old healthy male sick ? Any ideas ?
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