Question

Which of the following statements about type I and type II cytokines are incorrected? a. Type I and type II cytokine families are classified based upon the structural homology of their receptors. b. Type I and type II cytokine families are comprised of both Th1 and Th2 cytokines. c. Interferons are type II cytokines that promote viral growth while serving as anti-inflammatory and immunomodulatory factors. d. Members of the type I cytokine family share a characteristic motif consisting of an extracellular region containing four helices.

Short answer

A) Type I and type II cytokine families are classified based upon the structural homology of their receptors. B) Type I and type II cytokine families are comprised of both Th1 and Th2 cytokines. C) Interferons are type II cytokines that promote viral growth while serving as anti-inflammatory and immunomodulatory factors. D) Members of the type I cytokine family share a characteristic motif consisting of an extracellular region containing four helices. Answer: C

Step-by-step solution

Understanding type I and type II cytokines

Type I cytokines include interleukins and colony-stimulating factors that are involved in immune cell development and proliferation. They mainly act on hematopoietic cells and have a characteristic motif consisting of an extracellular region containing four helices. Type II cytokines include interferons and tumor necrosis factors, which are involved in immune responses against viral infections and tumor growth inhibition. They promote inflammation and have different functional roles compared to type I cytokines.

Evaluate Statement A

Statement A: "Type I and type II cytokine families are classified based upon the structural homology of their receptors." This statement is correct as the classification of type I and type II cytokines is indeed based on the structural similarity of their receptors.

Evaluate Statement B

Statement B: "Type I and type II cytokine families are comprised of both Th1 and Th2 cytokines." This statement is also correct as Th1 and Th2 cytokines can be found in both type I and type II cytokine families, with Th1 cytokines generally promoting cell-mediated immunity while Th2 cytokines support humoral immunity.

Evaluate Statement C

Statement C: "Interferons are type II cytokines that promote viral growth while serving as anti-inflammatory and immunomodulatory factors." This statement is incorrect because interferons, as type II cytokines, do not promote viral growth but rather inhibit viral replication and enhance immune responses against viral infections. They are in fact antiviral and immunomodulatory factors.

Evaluate Statement D

Statement D: "Members of the type I cytokine family share a characteristic motif consisting of an extracellular region containing four helices." This statement is correct, as type I cytokines indeed have a characteristic structure that includes an extracellular region containing four helices.

Identify the incorrect statement

Based on the evaluation of each statement, statement C is the incorrect option regarding type I and type II cytokines.

Key concepts

Type I Cytokines

Type I cytokines are essential players in the immune system. These molecules are primarily involved in the development and proliferation of immune cells. They include interleukins and colony-stimulating factors.
Type I cytokines mainly act on hematopoietic cells, which are the cells responsible for forming blood cellular components. What makes type I cytokines unique is their structural feature.
They share a characteristic motif of an extracellular region containing four helices, crucial for their interaction with specific receptors. These cytokines are vital for various immune functions, including encouraging the growth and differentiation of leukocytes, which are critical for the body's defense mechanisms.

Type II Cytokines

Type II cytokines serve distinct roles from type I cytokines, despite both being crucial for immune responses. These cytokines include interferons and tumor necrosis factors, which are key in combating viral infections and inhibiting tumor growth.
Unlike type I cytokines, type II cytokines broadly promote inflammation and modulate immune responses. They don't share the same structural motif as type I cytokines but have their unique receptor types.
Interferons, a subgroup of type II cytokines, play a pivotal role in immune defense by inhibiting viral replication and activating immune cells to fight off viral infections. Additionally, these cytokines can be anti-inflammatory and possess immunomodulatory properties that adjust the immune system's response to various threats.

Immune Response

The immune response is a complex process involving numerous cells and molecules. Cytokines, including both type I and type II varieties, are central to orchestrating this response.
When the body detects pathogens, cytokines signal immune cells to activate and respond. Type I and II cytokines work together, although they have different functions.

• Type I cytokines generally promote the development of immune cells and are important in initial immune cell recruitment.
• Type II cytokines, on the other hand, are more involved in clearing infections, particularly viral infections, and controlling inflammation.

Together, cytokines ensure that the immune system responds quickly and effectively to infections, maintaining the body's health and well-being. Understanding how these cytokines function can help researchers develop new therapies for immune-related diseases.