In developed countries, an enormous change has occurred within the human body over the past century—the loss of parasitic worms. Due to improvements in sanitation, roundworms that have inhabited human intestines (such as the hookworm above) and challenged our immune system for millions of years are no longer a threat. Does the end of this long-term relationship come at a cost? Explain how the adaptive and innate immune responses work together to defend the human body against infection by parasitic worms.

Verified step by step guidance

1. Understand the roles of the innate and adaptive immune systems: The innate immune system is the body's first line of defense, responding quickly to potential threats with general mechanisms. It includes physical barriers like skin and mucous membranes, and immune cells such as macrophages and neutrophils. The adaptive immune system, on the other hand, is more specialized and takes longer to respond, but it provides a targeted response to specific pathogens. It involves lymphocytes, including T cells and B cells, and the production of antibodies.
2. Recognize the initial response by the innate immune system: When a parasitic worm enters the body, the innate immune system responds first. Cells such as macrophages and dendritic cells recognize common patterns on pathogens (pathogen-associated molecular patterns, PAMPs) using pattern recognition receptors (PRRs). This triggers an inflammatory response to try to eliminate the invader.
3. Identify the activation of the adaptive immune system: Dendritic cells and other antigen-presenting cells (APCs) process and present antigens from the parasitic worms to T cells. This interaction, particularly involving helper T cells (Th cells), is crucial for the activation of the adaptive immune response.
4. Explore the role of Th2 cells in response to parasitic worms: In the case of parasitic worms, a specific type of helper T cell, known as Th2 cells, becomes predominant. Th2 cells release cytokines like IL-4, IL-5, and IL-13, which are important for activating and coordinating other immune cells such as eosinophils, basophils, and B cells that are particularly effective against larger parasites like worms.
5. Examine the production of antibodies and the role of B cells: Stimulated by cytokines from Th2 cells, B cells produce antibodies that are specific to antigens presented by the worms. These antibodies can bind to the parasites, marking them for destruction by other immune cells, or interfering with their function and ability to reproduce. This targeted response helps to eliminate the parasites from the body.