How do innate immune cells detect microbes?
The surfaces of microorganisms typically bear repeating patterns of molecular structure. The innate immune system recognizes such pathogens by means of receptors that bind features of these regular patterns; these receptors are sometimes known as pattern-recognition molecules.
Innate immune responses rely on the body's ability to recognize conserved features of pathogens that are not present in the uninfected host. These include many types of molecules on microbial surfaces and the double-stranded RNA of some viruses.
Antibodies. Antibodies help the body to fight microbes or the toxins (poisons) they produce. They do this by recognising substances called antigens on the surface of the microbe, or in the chemicals they produce, which mark the microbe or toxin as being foreign. The antibodies then mark these antigens for destruction.
Virus-associated molecules such as genomic DNA and RNA or double-stranded RNA (dsRNA) produced in virally infected cells can be recognized by host pattern-recognition receptors (PRRs) expressed in innate immune cells such as dendritic cells (DCs)1,2.
The innate immune system is the first part of the body to detect invaders such as viruses, bacteria, parasites and toxins, or to sense wounds or trauma.
The innate immune system is a universal and ancient form of host defense against infection. Innate immune recognition relies on a limited number of germline-encoded receptors. These receptors evolved to recognize conserved products of microbial metabolism produced by microbial pathogens, but not by the host.
Viruses initially activate the innate immune system, which recognizes viral components through pattern-recognition receptors (PRRs) (1-3). On the other hand, acquired immunity plays a major role in the responses to re-infection with viruses.
Innate immunity to pathogens relies on pattern recognition receptors (PRRs) which allow a limited range of immune cells to detect and respond rapidly to a wide range of pathogens that share common structures, known as pathogen associated molecular patterns (PAMPs).
It is now known that the Toll-like receptors (TLRs) are the principal signaling molecules through which mammals sense infection. Each TLR recognizes a restricted subset of molecules produced by microbes, and in some circumstances, only a single type of molecule is sensed (e.g., only LPS is sensed by TLR4).
The body reacts to disease-causing bacteria by increasing local blood flow (inflammation) and sending in cells from the immune system to attack and destroy the bacteria. Antibodies produced by the immune system attach to the bacteria and help in their destruction.
What can the immune response detect and destroy?
The immune system recognizes and destroys, or tries to destroy, substances that contain antigens. Your body's cells have proteins that are antigens. These include a group of antigens called HLA antigens. Your immune system learns to see these antigens as normal and usually does not react against them.
Cytotoxic T lymphocytes, natural killer (NK) cells and antiviral macrophages can recognize and kill virus-infected cells.
Summary: The innate immune system constitutes the first line of defense against invading microbial pathogens and relies on a large family of pattern recognition receptors (PRRs), which detect distinct evolutionarily conserved structures on pathogens, termed pathogen-associated molecular patterns (PAMPs).
When the body senses foreign substances (called antigens), the immune system works to recognize the antigens and get rid of them. B lymphocytes are triggered to make antibodies (also called immunoglobulins). These proteins lock onto specific antigens.
The three methods used for microbial identification are genotypic, proteotypic, and phenotypic. Genotypic identification analyzes the sequences in the rRNA regions of bacteria and fungi, whereas proteotypic methods analyzes the ribosomal proteins expressed.
What are the examples of microbial substances recognized by the innate immune system, and what are the receptors for these substances? Examples include LPS recognized by Toll-like receptor-4 (TLR-4), flagellin recognized by TLR-5, dsRNA by TLRs 3,7,8, mannans by mannose-binding protein.
Your white blood cells lock on to the germs in order to absorb or destroy them. They produce antibodies that latch onto the germs. Experience makes your immune system stronger. The first time your body comes into contact with a certain type of germ, your immune response may take a while.
One of the most remarkable features of the immune system is its ability to “remember” past encounters with pathogens like viruses, bacteria, and parasites. This phenomenon, known as immunological memory, is controlled by two main immune cell types: memory T and B cells.
They recognize and help destroy particular pathogens in body fluids and cells. They also destroy certain cancer cells.
In opsonization, an antibody-bound pathogen serves as a red flag to alert immune cells like neutrophils and macrophages, to engulf and digest the pathogen. Complement is a process for directly destroying, or lysing, bacteria.
How does the immune system respond to disease?
The acquired immune system, with help from the innate system, makes special proteins (called antibodies) to protect your body from a specific invader. These antibodies are developed by cells called B lymphocytes after the body has been exposed to the invader. The antibodies stay in your child's body.
Foreign particles can also be recognized by phagocytes through soluble molecules that will bind to the particles, tagging them for ingestion. Once on the surface of the target particle, these molecules, called opsonins, are in turn recognized by specific receptors on the membrane of phagocytes.
If the virus comes back, the bacterium makes RNA from the region of CRISPR specific for that virus. These RNA copies pair up with some cas (CRISPR-associated) proteins. The RNA guides the cas protein to the invading viral DNA, so the protein can destroy it. No more viral DNA, no new viruses.
| Question | Answer |
|---|---|
| The nurse understands that the innate immune response involves which components? | 1. Fungi 2. Low Stomach pH 3. Skin 4. Capillary dilation |
| Introducing the patient's normal flora into which body area increases the risk for infection? | Urinary bladder |
In the innate immune response, pattern recognition receptors (PRRs) are engaged to detect specific viral components such as viral RNA or DNA or viral intermediate products and to induce type I interferons (IFNs) and other pro-inflammatory cytokines in the infected cells and other immune cells.