Immune and Lymphatic Systems - MCAT Biological and Biochemical Foundations of Living Systems
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In the event of re-infection with the same pathogen, which immune cell allows for a quick response?
In the event of re-infection with the same pathogen, which immune cell allows for a quick response?
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Memory B-cells are differentiated B-cells that specifically allow for a quick response to re-infection with the same antigen. The memory B-cells proliferate after coming into contact with an antigen that they recognize, spawning plasma cells that can secrete antibodies into circulation. Helper T-cells activate immature B-cells, while natural killer cells release perforin to kill invading bacteria.
Memory B-cells are differentiated B-cells that specifically allow for a quick response to re-infection with the same antigen. The memory B-cells proliferate after coming into contact with an antigen that they recognize, spawning plasma cells that can secrete antibodies into circulation. Helper T-cells activate immature B-cells, while natural killer cells release perforin to kill invading bacteria.
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Which immunoglobulin is the predominant subclass that can cross the placenta?
Which immunoglobulin is the predominant subclass that can cross the placenta?
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IgG (exists as a monomer in the blood) and IgE are both small enough to cross the placenta however, IgE is present in very low levels in the plasma.
IgG (exists as a monomer in the blood) and IgE are both small enough to cross the placenta however, IgE is present in very low levels in the plasma.
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Which of the following is not a true statement regarding germinal centers?
Which of the following is not a true statement regarding germinal centers?
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T cells, especially CD4+ follicular helper T cells, are absolutely critical and necessary for the induction and maintenance of germinal centers.
T cells, especially CD4+ follicular helper T cells, are absolutely critical and necessary for the induction and maintenance of germinal centers.
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Where do the T-cells of the immune system mature into functional T-cells?
Where do the T-cells of the immune system mature into functional T-cells?
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T-cells are originally formed from stem cells in the bone marrow, however, T-cells, unlike B-cells, mature in the thymus. The thymus is a lymphoid organ located in the upper chest.
In contrast, B-cells are formed and mature in the bone marrow.
T-cells are originally formed from stem cells in the bone marrow, however, T-cells, unlike B-cells, mature in the thymus. The thymus is a lymphoid organ located in the upper chest.
In contrast, B-cells are formed and mature in the bone marrow.
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Which of the following systems is NOT directly aided by the lymphatic system?
Which of the following systems is NOT directly aided by the lymphatic system?
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The lymphatic system has a variety of functions in the body. It collects excess interstitial fluid and returns it to the blood (cardiovascular system), it has lymph nodes that screen the lymphatic fluid for pathogens (immune system), and it reroutes fat digestates to the neck veins (digestive system). The lymphatic system does not aid the endocrine system, as hormones travel in the bloodstream.
The lymphatic system has a variety of functions in the body. It collects excess interstitial fluid and returns it to the blood (cardiovascular system), it has lymph nodes that screen the lymphatic fluid for pathogens (immune system), and it reroutes fat digestates to the neck veins (digestive system). The lymphatic system does not aid the endocrine system, as hormones travel in the bloodstream.
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In the event of re-infection with the same pathogen, which immune cell allows for a quick response?
In the event of re-infection with the same pathogen, which immune cell allows for a quick response?
Tap to reveal answer
Memory B-cells are differentiated B-cells that specifically allow for a quick response to re-infection with the same antigen. The memory B-cells proliferate after coming into contact with an antigen that they recognize, spawning plasma cells that can secrete antibodies into circulation. Helper T-cells activate immature B-cells, while natural killer cells release perforin to kill invading bacteria.
Memory B-cells are differentiated B-cells that specifically allow for a quick response to re-infection with the same antigen. The memory B-cells proliferate after coming into contact with an antigen that they recognize, spawning plasma cells that can secrete antibodies into circulation. Helper T-cells activate immature B-cells, while natural killer cells release perforin to kill invading bacteria.
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Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the loss of tolerance to self antigens leading to the presence of high autoantibody titers. Dysregulated peripheral tolerance and hyperactive germinal centers have been proposed to be one of the driving forces behind the accumulation of high autoantibodies.
What immune cell type is the product of germinal centers and most likely the cell mediating the production of autoantibodies?
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the loss of tolerance to self antigens leading to the presence of high autoantibody titers. Dysregulated peripheral tolerance and hyperactive germinal centers have been proposed to be one of the driving forces behind the accumulation of high autoantibodies.
What immune cell type is the product of germinal centers and most likely the cell mediating the production of autoantibodies?
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Plasma cells are the main product of germinal centers and are potent antibody factories. Dysregulated peripheral tolerance and germinal centers can lead to the production of plasma cells that are reactive towards self-nuclear antigens.
Plasma cells are the main product of germinal centers and are potent antibody factories. Dysregulated peripheral tolerance and germinal centers can lead to the production of plasma cells that are reactive towards self-nuclear antigens.
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Which of the following is an example of a primary lymphoid organ?
Which of the following is an example of a primary lymphoid organ?
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The thymus is a primary lymphoid organ (along with bone marrow). The thymus is where T cells differentiate and mature. All of the other organs listed are secondary lymphoid organs, where lymphocytes reside and respond to antigenic challenges and foreign pathogens.
The thymus is a primary lymphoid organ (along with bone marrow). The thymus is where T cells differentiate and mature. All of the other organs listed are secondary lymphoid organs, where lymphocytes reside and respond to antigenic challenges and foreign pathogens.
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Major histocompatibility complex (MHC) II molecules are responsible for displaying antigens from what invading pathogen?
Major histocompatibility complex (MHC) II molecules are responsible for displaying antigens from what invading pathogen?
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The "self" antigens that prevent T-cells from attacking the body are called MHC molecules. These molecules come in two classes: class I and class II. RNA, DNA, and proteins from bacteria are displayed after the bacterium is ingested by an antigen-presenting cell using MHC class II molecules. The antigen-presenting cell reports the MHC molecule corresponding to the bacteria to a helper T-cells. Once the helper T-cells see this unrecognized part of the bacterium, and detect it as different from "self," they can initiate the adaptive immune response.
The "self" antigens that prevent T-cells from attacking the body are called MHC molecules. These molecules come in two classes: class I and class II. RNA, DNA, and proteins from bacteria are displayed after the bacterium is ingested by an antigen-presenting cell using MHC class II molecules. The antigen-presenting cell reports the MHC molecule corresponding to the bacteria to a helper T-cells. Once the helper T-cells see this unrecognized part of the bacterium, and detect it as different from "self," they can initiate the adaptive immune response.
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Which immunoglobulin is the predominant subclass that can cross the placenta?
Which immunoglobulin is the predominant subclass that can cross the placenta?
Tap to reveal answer
IgG (exists as a monomer in the blood) and IgE are both small enough to cross the placenta however, IgE is present in very low levels in the plasma.
IgG (exists as a monomer in the blood) and IgE are both small enough to cross the placenta however, IgE is present in very low levels in the plasma.
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Which of the following is not a true statement regarding germinal centers?
Which of the following is not a true statement regarding germinal centers?
Tap to reveal answer
T cells, especially CD4+ follicular helper T cells, are absolutely critical and necessary for the induction and maintenance of germinal centers.
T cells, especially CD4+ follicular helper T cells, are absolutely critical and necessary for the induction and maintenance of germinal centers.
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Where do the T-cells of the immune system mature into functional T-cells?
Where do the T-cells of the immune system mature into functional T-cells?
Tap to reveal answer
T-cells are originally formed from stem cells in the bone marrow, however, T-cells, unlike B-cells, mature in the thymus. The thymus is a lymphoid organ located in the upper chest.
In contrast, B-cells are formed and mature in the bone marrow.
T-cells are originally formed from stem cells in the bone marrow, however, T-cells, unlike B-cells, mature in the thymus. The thymus is a lymphoid organ located in the upper chest.
In contrast, B-cells are formed and mature in the bone marrow.
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Which of the following systems is NOT directly aided by the lymphatic system?
Which of the following systems is NOT directly aided by the lymphatic system?
Tap to reveal answer
The lymphatic system has a variety of functions in the body. It collects excess interstitial fluid and returns it to the blood (cardiovascular system), it has lymph nodes that screen the lymphatic fluid for pathogens (immune system), and it reroutes fat digestates to the neck veins (digestive system). The lymphatic system does not aid the endocrine system, as hormones travel in the bloodstream.
The lymphatic system has a variety of functions in the body. It collects excess interstitial fluid and returns it to the blood (cardiovascular system), it has lymph nodes that screen the lymphatic fluid for pathogens (immune system), and it reroutes fat digestates to the neck veins (digestive system). The lymphatic system does not aid the endocrine system, as hormones travel in the bloodstream.
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Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
What is the best characterization of the immune response described in the passage?
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
What is the best characterization of the immune response described in the passage?
Tap to reveal answer
The initial response is an effort to repair physical damage, while the chronic response involves the recognition of antigens. Innate immunity refers to the body's natural untargeted defenses, such as the cells that would work to repair damage. Adaptive immunity is targeted to specific pathogens via antigen presentation. Thus, the pattern described in the passage is initially innate immunity, then adaptive immunity.
The initial response is an effort to repair physical damage, while the chronic response involves the recognition of antigens. Innate immunity refers to the body's natural untargeted defenses, such as the cells that would work to repair damage. Adaptive immunity is targeted to specific pathogens via antigen presentation. Thus, the pattern described in the passage is initially innate immunity, then adaptive immunity.
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Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Which compound is most likely responsible for initiating the inflammation response that results from the autoimmune attack?
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Which compound is most likely responsible for initiating the inflammation response that results from the autoimmune attack?
Tap to reveal answer
Fibrin and fibrinogen are involved in wound healing and scab formation. Dopamine is a neurotransmitter in the brain. Fibrogen is not a real protein at all.
Histamine is the primary inflammatory molecule in the body and is released from mast cells during an immune response or trauma.
Fibrin and fibrinogen are involved in wound healing and scab formation. Dopamine is a neurotransmitter in the brain. Fibrogen is not a real protein at all.
Histamine is the primary inflammatory molecule in the body and is released from mast cells during an immune response or trauma.
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Which of the following correctly matches the type of immunity to the way it was recieved?
Which of the following correctly matches the type of immunity to the way it was recieved?
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Active immunity is when you are exposed to a pathogen, either through vaccination, another person with the disease, or any other means, and your body responds by producing specific antibodies with B-cells to destroy the pathogen. Passive immunity is acquired from antibody transfer, so the body does not produce its own antibodies.
Active immunity is when you are exposed to a pathogen, either through vaccination, another person with the disease, or any other means, and your body responds by producing specific antibodies with B-cells to destroy the pathogen. Passive immunity is acquired from antibody transfer, so the body does not produce its own antibodies.
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Which of these choices is not a function of T-cells?
Which of these choices is not a function of T-cells?
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The only choice that is not a function of any type of T-cell is the direct production of antibodies (which is performed by B-cells). Cytotoxic T-cells kill other cells that are bound to antigen/MHC-I complexes. Suppressor T-cells tone down the response of both B- and T-cells, and helper T-cells secrete cytokines, which increase the activity of many other immune cell types.
The only choice that is not a function of any type of T-cell is the direct production of antibodies (which is performed by B-cells). Cytotoxic T-cells kill other cells that are bound to antigen/MHC-I complexes. Suppressor T-cells tone down the response of both B- and T-cells, and helper T-cells secrete cytokines, which increase the activity of many other immune cell types.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The first line of defense by a human host against a potential Neisseria infection is which of the following?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The first line of defense by a human host against a potential Neisseria infection is which of the following?
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Innate defenses, such as the skin or macrophages, are the first line of defense against infection. Other responses only become effective if a pathogen cannot be repelled by innate mechanisms.
Innate defenses, such as the skin or macrophages, are the first line of defense against infection. Other responses only become effective if a pathogen cannot be repelled by innate mechanisms.
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Cryptosporidium is a genus of gastrointestinal parasite that infects the intestinal epithelium of mammals. Cryptosporidium is water-borne, and is an apicomplexan parasite. This phylum also includes Plasmodium, Babesia, and Toxoplasma.
Apicomplexans are unique due to their apicoplast, an apical organelle that helps penetrate mammalian epithelium. In the case of cryptosporidium, there is an interaction between the surface proteins of mammalian epithelial tissue and those of the apical portion of the cryptosporidium infective stage, or oocyst. A scientist is conducting an experiment to test the hypothesis that the oocyst secretes a peptide compound that neutralizes intestinal defense cells. These defense cells are resident in the intestinal epithelium, and defend the tissue by phagocytizing the oocysts.
She sets up the following experiment:
As the neutralizing compound was believed to be secreted by the oocyst, the scientist collected oocysts onto growth media. The oocysts were grown among intestinal epithelial cells, and then the media was collected. The media was then added to another plate where Toxoplasma gondii was growing with intestinal epithelial cells. A second plate of Toxoplasma gondii was grown with the same type of intestinal epithelium, but no oocyst-sourced media was added.
A patient is hiking through Nepal and comes down with a case of diarrhea caused by cryptosporidium. You determine that his body was fighting this infection mainly by mounting an antibody response. Where do the cells most directly responsible for this response develop?
Cryptosporidium is a genus of gastrointestinal parasite that infects the intestinal epithelium of mammals. Cryptosporidium is water-borne, and is an apicomplexan parasite. This phylum also includes Plasmodium, Babesia, and Toxoplasma.
Apicomplexans are unique due to their apicoplast, an apical organelle that helps penetrate mammalian epithelium. In the case of cryptosporidium, there is an interaction between the surface proteins of mammalian epithelial tissue and those of the apical portion of the cryptosporidium infective stage, or oocyst. A scientist is conducting an experiment to test the hypothesis that the oocyst secretes a peptide compound that neutralizes intestinal defense cells. These defense cells are resident in the intestinal epithelium, and defend the tissue by phagocytizing the oocysts.
She sets up the following experiment:
As the neutralizing compound was believed to be secreted by the oocyst, the scientist collected oocysts onto growth media. The oocysts were grown among intestinal epithelial cells, and then the media was collected. The media was then added to another plate where Toxoplasma gondii was growing with intestinal epithelial cells. A second plate of Toxoplasma gondii was grown with the same type of intestinal epithelium, but no oocyst-sourced media was added.
A patient is hiking through Nepal and comes down with a case of diarrhea caused by cryptosporidium. You determine that his body was fighting this infection mainly by mounting an antibody response. Where do the cells most directly responsible for this response develop?
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Antibodies are produced by B-cells, which develop in the bone marrow. T-cells develop in the thymus.
You can remember B for bone marrow, T for thymus.
Antibodies are produced by B-cells, which develop in the bone marrow. T-cells develop in the thymus.
You can remember B for bone marrow, T for thymus.
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Cryptosporidium is a genus of gastrointestinal parasite that infects the intestinal epithelium of mammals. Cryptosporidium is water-borne, and is an apicomplexan parasite. This phylum also includes Plasmodium, Babesia, and Toxoplasma.
Apicomplexans are unique due to their apicoplast, an apical organelle that helps penetrate mammalian epithelium. In the case of cryptosporidium, there is an interaction between the surface proteins of mammalian epithelial tissue and those of the apical portion of the cryptosporidium infective stage, or oocyst. A scientist is conducting an experiment to test the hypothesis that the oocyst secretes a peptide compound that neutralizes intestinal defense cells. These defense cells are resident in the intestinal epithelium, and defend the tissue by phagocytizing the oocysts.
She sets up the following experiment:
As the neutralizing compound was believed to be secreted by the oocyst, the scientist collected oocysts onto growth media. The oocysts were grown among intestinal epithelial cells, and then the media was collected. The media was then added to another plate where Toxoplasma gondii was growing with intestinal epithelial cells. A second plate of Toxoplasma gondii was grown with the same type of intestinal epithelium, but no oocyst-sourced media was added.
In the initial stages of a cryptosporidium infection, you can observe macrophages migrating to the area of infection. This process is called chemotaxis. What is likely to be the chemical mediator responsible for chemotaxis?
Cryptosporidium is a genus of gastrointestinal parasite that infects the intestinal epithelium of mammals. Cryptosporidium is water-borne, and is an apicomplexan parasite. This phylum also includes Plasmodium, Babesia, and Toxoplasma.
Apicomplexans are unique due to their apicoplast, an apical organelle that helps penetrate mammalian epithelium. In the case of cryptosporidium, there is an interaction between the surface proteins of mammalian epithelial tissue and those of the apical portion of the cryptosporidium infective stage, or oocyst. A scientist is conducting an experiment to test the hypothesis that the oocyst secretes a peptide compound that neutralizes intestinal defense cells. These defense cells are resident in the intestinal epithelium, and defend the tissue by phagocytizing the oocysts.
She sets up the following experiment:
As the neutralizing compound was believed to be secreted by the oocyst, the scientist collected oocysts onto growth media. The oocysts were grown among intestinal epithelial cells, and then the media was collected. The media was then added to another plate where Toxoplasma gondii was growing with intestinal epithelial cells. A second plate of Toxoplasma gondii was grown with the same type of intestinal epithelium, but no oocyst-sourced media was added.
In the initial stages of a cryptosporidium infection, you can observe macrophages migrating to the area of infection. This process is called chemotaxis. What is likely to be the chemical mediator responsible for chemotaxis?
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Cytokines and chemokines are general classes of inflammatory mediators secreted by inflammatory cells like macrophages. They not only govern inflammation, but can also recruit surrounding cells via chemotaxis.
Cytokines and chemokines are general classes of inflammatory mediators secreted by inflammatory cells like macrophages. They not only govern inflammation, but can also recruit surrounding cells via chemotaxis.
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