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Cytokines are large proteins, typically exceeding 100 kilodaltons, primarily involved in structural support for cells.
Answer: False
Explanation: Cytokines are small proteins, typically 5-25 kilodaltons, functioning in cell signaling rather than structural support.
Hormones and growth factors are always strictly excluded from the classification of cytokines.
Answer: False
Explanation: While generally excluded, there can be overlap in terminology between cytokines, hormones, and growth factors.
The term 'cytokine' originates from Greek words meaning 'cell movement'.
Answer: True
Explanation: The term 'cytokine' combines the Greek words 'kytos' (cell) and 'kinēsis' (movement), reflecting their role in cellular communication.
What is the typical size range for cytokines?
Answer: 5-25 kilodaltons
Explanation: Cytokines are typically small proteins, generally measuring between 5 and 25 kilodaltons (kDa).
Which of the following is NOT typically classified as a cytokine?
Answer: Hormone
Explanation: While there can be overlap, hormones are generally excluded from the classification of cytokines, which include interleukins, chemokines, and tumor necrosis factors.
The etymology of 'cytokine' combines Greek words meaning:
Answer: Cell movement
Explanation: The term 'cytokine' is derived from the Greek words 'kytos' (cell) and 'kinēsis' (movement), reflecting their role in cellular communication.
Cytokines are exclusively produced by immune cells like white blood cells.
Answer: False
Explanation: Cytokines are produced by a wide variety of cells, including immune cells, endothelial cells, fibroblasts, and connective tissue cells, not exclusively immune cells.
Cytokines typically pass through cell membranes to exert their effects.
Answer: False
Explanation: Cytokines are generally too large to pass through cell membranes; they exert effects by binding to specific cell surface receptors.
Unlike classical hormones that circulate in nanomolar concentrations, cytokines are always found in picomolar concentrations.
Answer: False
Explanation: Classical hormones typically circulate in nanomolar concentrations, whereas some cytokines can be found in picomolar concentrations and increase significantly during inflammation.
Cytokines can only signal to nearby cells (paracrine signaling).
Answer: False
Explanation: Cytokines can signal via autocrine (acting on the same cell), paracrine (acting on nearby cells), and endocrine (acting on distant cells via bloodstream) mechanisms.
The Seven transmembrane helix family is a classification of cytokine receptors that are primarily involved in structural integrity.
Answer: False
Explanation: The Seven transmembrane helix family includes receptors for hormones, neurotransmitters, and chemokines, not primarily structural integrity.
Cytokines influence cellular functions by binding to intracellular receptors, directly affecting DNA transcription.
Answer: False
Explanation: Cytokines influence cellular functions by binding to cell surface receptors, triggering intracellular signaling cascades that can alter gene expression.
Cytokine redundancy means that each cytokine has a unique and non-overlapping function.
Answer: False
Explanation: Cytokine redundancy refers to the phenomenon where multiple cytokines perform similar functions, indicating overlap rather than unique, non-overlapping roles.
The common gamma chain (γc) is a unique component found only in receptors for IL-2.
Answer: False
Explanation: The common gamma chain (γc) is a shared component for receptors of multiple cytokines, including IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, and its deficiency causes X-SCID.
Cytokines primarily exert their effects by:
Answer: Binding to specific cytokine receptors located on the surface of target cells.
Explanation: Cytokines primarily exert their effects by binding to specific receptors found on the surface of target cells, initiating intracellular signaling pathways.
How do cytokines differ from classical hormones in terms of cellular source?
Answer: Cytokines are produced by a widespread distribution of cells, unlike hormones which are usually secreted from discrete glands.
Explanation: Cytokines are produced by a widespread distribution of cells, whereas classical hormones are typically secreted from discrete glands.
Which mode of cytokine signaling involves a cytokine acting on the same cell that released it?
Answer: Autocrine signaling
Explanation: Autocrine signaling occurs when a cytokine acts on the same cell that secreted it.
What is the significance of the common gamma chain (γc) in cytokine receptor families?
Answer: It is a shared component for receptors of multiple cytokines, and its deficiency causes X-SCID.
Explanation: The common gamma chain (γc) is a shared component for receptors of multiple cytokines, and its deficiency leads to X-linked Severe Combined Immunodeficiency (X-SCID).
What is the significance of the seven transmembrane helix family of cytokine receptors?
Answer: They are receptors for hormones and neurotransmitters, and include chemokine receptors.
Explanation: The seven transmembrane helix family includes receptors for hormones and neurotransmitters, and also encompasses chemokine receptors.
Cytokines binding to antibodies can result in:
Answer: A stronger immune effect compared to the cytokine alone.
Explanation: Cytokines binding to antibodies can result in a stronger immune effect compared to the cytokine acting independently.
What is the significance of the IL-17 receptor family's structure?
Answer: It shares conserved structural motifs, including an extracellular fibronectin III-like domain.
Explanation: The IL-17 receptor family shares conserved structural motifs, such as an extracellular fibronectin III-like domain, and shows little homology with other cytokine receptor families.
Structurally, cytokines are classified into four main types, including the IL-1 family and the four-alpha-helix bundle family.
Answer: True
Explanation: Cytokines are structurally classified into four main types: the four-alpha-helix bundle family, the IL-1 family, cysteine knot cytokines, and the IL-17 family.
Type 1 immunological cytokines enhance antibody responses, while Type 2 cytokines enhance cellular immune responses.
Answer: False
Explanation: Type 1 cytokines enhance cellular immune responses, while Type 2 cytokines enhance antibody responses.
The IL-1 family of cytokines, including IL-1 and IL-18, is structurally characterized by a four-alpha-helix bundle.
Answer: False
Explanation: While the four-alpha-helix bundle is a major structural classification, the IL-1 family has a different structural composition and is not characterized by this specific bundle.
Which of the following is a structural classification of cytokines?
Answer: Four-alpha-helix bundle
Explanation: The 'four-alpha-helix bundle' is a recognized structural classification for cytokines.
Type 1 immunological cytokines are primarily responsible for:
Answer: Enhancing cellular immune responses.
Explanation: Type 1 immunological cytokines are primarily responsible for enhancing cellular immune responses.
How does the IL-1 family of cytokines differ structurally from the four-alpha-helix bundle family?
Answer: The IL-1 family has a different structural composition, not detailed as a four-alpha-helix bundle.
Explanation: The IL-1 family possesses a distinct structural composition compared to the four-alpha-helix bundle family, with its specific structure not being defined by the latter.
What is the primary function of chemokines within the cytokine classification?
Answer: Mediating chemoattraction.
Explanation: Chemokines, a type of cytokine, primarily function by mediating chemoattraction, guiding cell movement.
What is the primary role of interferons as cytokines?
Answer: Involved in antiviral responses.
Explanation: Interferons, as cytokines, are primarily involved in antiviral responses, forming a key part of the innate immune system.
What is the significance of the cysteine knot cytokine group?
Answer: It is characterized by a structure involving cysteine residues forming a knot-like structure.
Explanation: The cysteine knot cytokine group is characterized by a unique structure involving cysteine residues that form a knot-like arrangement.
What is the significance of the IL-1 family of cytokines?
Answer: They are known to play significant roles in inflammation and immune responses.
Explanation: The IL-1 family of cytokines is significant for its roles in inflammation and immune responses.
Cytokines are most critical in the nervous system, regulating neurotransmitter release.
Answer: False
Explanation: Cytokines are especially critical within the immune system, playing significant roles in immune responses and inflammation, rather than primarily in the nervous system's neurotransmitter regulation.
Cytokines are not involved in embryo development, as this process is solely regulated by hormones.
Answer: False
Explanation: Cytokines are involved in embryo development, playing critical roles in stages such as zona hatching and implantation.
'Inflammaging' is a condition characterized by acute, high-grade inflammation in young individuals.
Answer: False
Explanation: 'Inflammaging' is characterized by chronic, low-grade inflammation associated with aging, not acute inflammation in young individuals.
A 2024 study found a negative correlation between plasma interleukin IL-2 levels and fatigue in narcolepsy patients.
Answer: False
Explanation: A 2024 study indicated a positive correlation between plasma IL-2 levels and fatigue in narcolepsy patients.
A 2025 study found that mRNA COVID vaccine recipients showed decreased cytokine levels one year post-vaccination.
Answer: False
Explanation: A 2025 study found that mRNA COVID vaccine recipients showed elevated cytokine levels one year post-vaccination.
A cytokine storm is a condition where cytokine secretion is suppressed, leading to immune deficiency.
Answer: False
Explanation: A cytokine storm is a dangerous condition triggered by the over-secretion of cytokines, not suppression, and can lead to severe inflammatory responses.
Cytokines like IL-10 and TGF-β are involved in promoting anti-tumor immunity.
Answer: False
Explanation: Cytokines such as IL-10, IL-35, and TGF-β are involved in suppressing anti-tumor immunity, contributing to tumor immune escape.
Neutralizing autoantibodies against type I interferons were found in a significant percentage of patients with mild COVID-19 in 2020.
Answer: False
Explanation: Neutralizing autoantibodies against type I interferons were found in patients with severe, not mild, COVID-19, suggesting a role in disease severity.
Cytokines are integral to the systemic inflammatory response syndrome (SIRS) associated with acute pancreatitis.
Answer: True
Explanation: Cytokines are integral to the cascade of events in acute pancreatitis, contributing to the systemic inflammatory response syndrome (SIRS).
In which biological system are cytokines particularly critical?
Answer: The immune system
Explanation: Cytokines are particularly critical within the immune system, where they mediate a wide range of immune responses and inflammatory processes.
The 'inflammaging' phenomenon is characterized by:
Answer: Chronic, low-grade inflammation associated with aging.
Explanation: 'Inflammaging' is defined as chronic, low-grade inflammation that is associated with the aging process.
According to a 2024 study, what is the observed correlation between plasma IL-2 levels and fatigue in narcolepsy patients?
Answer: A positive correlation.
Explanation: A 2024 study observed a positive correlation between plasma IL-2 levels and fatigue in patients diagnosed with narcolepsy.
What dangerous condition is triggered by the over-secretion of cytokines?
Answer: Cytokine storm
Explanation: The over-secretion of cytokines can trigger a dangerous condition known as a cytokine storm.
Cytokines like IL-10, IL-35, and TGF-β are involved in which process related to tumors?
Answer: Suppressing anti-tumor immunity.
Explanation: Cytokines such as IL-10, IL-35, and TGF-β are involved in suppressing anti-tumor immunity, thereby facilitating tumor immune escape.
Cytokines are integral to the cascade of events in acute pancreatitis and contribute to:
Answer: Systemic inflammatory response syndrome (SIRS).
Explanation: In acute pancreatitis, cytokines contribute to the development of the systemic inflammatory response syndrome (SIRS).
In the context of the COVID-19 pandemic, cytokine release storms were associated with:
Answer: Extensive lung tissue damage and dysfunctional coagulation.
Explanation: Cytokine release storms during the COVID-19 pandemic were associated with extensive lung tissue damage and dysfunctional coagulation.
What is the role of cytokines in the context of schizophrenia and major depression?
Answer: Studies suggest cytokine dysregulation may play a role in their pathophysiology.
Explanation: Studies suggest that cytokine dysregulation may contribute to the pathophysiology of conditions such as schizophrenia and major depression.
Cytokines are implicated in cancer through various mechanisms, including:
Answer: Tumor immune escape and disruption of normal tissue integrity.
Explanation: Cytokines are implicated in cancer through mechanisms such as promoting tumor immune escape and disrupting normal tissue integrity.
What is the role of cytokines in the context of hemorrhagic stroke?
Answer: They can become dysregulated and pathological, contributing to inflammatory processes.
Explanation: In hemorrhagic stroke, cytokines can become dysregulated and pathological, contributing to the inflammatory processes that follow the event.
What is the significance of autoantibodies against type I interferons in severe COVID-19?
Answer: They suggest that autoantibodies targeting cytokines can play a role in disease severity.
Explanation: The presence of neutralizing autoantibodies against type I interferons in severe COVID-19 suggests that autoantibodies targeting cytokines can contribute to disease severity.
Erythropoietin (EPO) is an example of a cytokine used therapeutically to treat anemia.
Answer: True
Explanation: Erythropoietin (EPO) is one of several cytokines developed as protein therapeutics, used clinically to treat anemia.
Interleukin-11 (IL-11) is used to treat thrombocytopenia in cancer patients.
Answer: True
Explanation: Interleukin-11 (IL-11) is employed therapeutically to manage thrombocytopenia, a condition often seen in cancer patients undergoing treatment.
Which of the following is an example of a cytokine used as a therapeutic drug?
Answer: Erythropoietin (EPO)
Explanation: Erythropoietin (EPO) is an example of a cytokine that has been developed into a therapeutic drug for conditions like anemia.
Which cytokine is used to treat thrombocytopenia in cancer patients?
Answer: Interleukin-11 (IL-11)
Explanation: Interleukin-11 (IL-11) is utilized therapeutically to treat thrombocytopenia in cancer patients.
Historical classifications like lymphokines and interleukins are still considered accurate and precise due to the strict specificity of cytokine functions.
Answer: False
Explanation: These historical classifications are now considered obsolete due to the considerable redundancy and pleiotropism of cytokine functions, which are not strictly defined by these older categories.
Interferon-alpha was first identified in 1974, shortly after the term 'cytokine' was proposed.
Answer: False
Explanation: Interferon-alpha was identified in 1957, predating the 1974 proposal of the term 'cytokine'.
The term 'cytokine' was proposed by biochemist Nobel laureate Stanley Cohen.
Answer: False
Explanation: The term 'cytokine' was proposed in 1974 by pathologist Stanley Cohen, M.D., not the Nobel laureate biochemist Stanley Cohen.
Why are historical classifications like 'lymphokines' and 'interleukins' now considered obsolete?
Answer: Due to redundancy and pleiotropism, cytokine functions are not strictly defined by these old categories.
Explanation: Historical classifications are obsolete because cytokine functions exhibit redundancy and pleiotropism, meaning their roles are not strictly confined to these early categories.
The term 'cytokine' was proposed in 1974 by which individual?
Answer: Stanley Cohen, M.D., a pathologist.
Explanation: The term 'cytokine' was proposed in 1974 by pathologist Stanley Cohen, M.D.