Shanice was a vibrant 16-year-old who was enjoying her high school years. As a good student, she loved attending school and woke every morning eager to start the day. A popular girl, she was surrounded by many friends who all enjoyed each other’s company.
From an early age, Shanice had been susceptible to recurrent viral and bacterial infections. No matter what she tried, she tended to have numerous infections every year which put a damper on some of her social activities.
Recently, she had been experiencing recurrent lung infections, spending a week in the hospital with pneumonia and recurrent herpes viral infections. Concerned over these recurrent infections, Shanice was sent to an immunologist for further consultation.
Tests were performed to evaluate the number and activities of her B-cells, T-cells, and natural killer cells. Results showed that Shanice had low numbers and decreased activity of her natural killer cells.
Keep in mind that natural killer cells are part of the innate immune response.
Deliverables
Answer the following questions and save your responses in a Microsoft Word document. Provide a scholarly resource to support your answers.
- Why are natural killer cells considered to be part of the innate immune response?
- What types of cells do natural killer cells act against?
- Describe the process whereby natural killer cells kill other cells and the role of macrophages in the process.
- The Immunologist cautioned Shanice that she may be more susceptible to virally induced cancers. Why did the Immunologist state this?
- What treatments or other options does Shanice have to counteract the natural killer cell deficiency
- Why are natural killer cells considered to be part of the innate immune response? Natural killer (NK) cells are considered part of the innate immune response because they provide rapid and non-specific immune defense against infected or cancerous cells without the need for prior sensitization or activation. Unlike adaptive immune cells, such as B and T lymphocytes, NK cells do not require prior exposure to specific antigens to recognize and eliminate target cells. They have a wide range of receptors on their surface that allow them to detect and respond to abnormal or stressed cells, such as virus-infected cells or tumor cells, in a more general manner.
Scholarly resource: Source: Vivier, E., Raulet, D.H., Moretta, A., Caligiuri, M.A., Zitvogel, L., Lanier, L.L., … & Ugolini, S. (2011). Innate or adaptive immunity? The example of natural killer cells. Science, 331(6013), 44-49.
- What types of cells do natural killer cells act against? Natural killer cells act against various types of target cells, including virus-infected cells, tumor cells, and cells undergoing stress or cellular damage. These target cells may express certain surface markers that distinguish them from healthy cells, such as downregulated major histocompatibility complex (MHC) class I molecules or the presence of stress-induced ligands. By recognizing these abnormal features, NK cells can directly kill the target cells without the need for specific antigen recognition.
Scholarly resource: Source: Sun, J.C., & Lanier, L.L. (2011). NK cell development, homeostasis and function: parallels with CD8+ T cells. Nature Reviews Immunology, 11(10), 645-657.
- Describe the process whereby natural killer cells kill other cells and the role of macrophages in the process. Natural killer cells have multiple mechanisms to kill other cells. One of the primary mechanisms is through the release of cytotoxic granules containing perforin and granzymes. Perforin creates pores in the target cell’s membrane, allowing granzymes to enter the cell. Granzymes induce apoptosis (programmed cell death) by activating caspases, which are proteases involved in cell death pathways.
Macrophages play a role in the process by phagocytosing the target cells after NK cell-mediated killing. When NK cells induce apoptosis in target cells, the dying cells release chemotactic signals that attract macrophages. The macrophages then engulf and digest the apoptotic cells, clearing them from the tissue.
Scholarly resource: Source: Smyth, M.J., Hayakawa, Y., & Takeda, K. (2002). Y- and N-dependent mechanisms of tumor rejection. Trends in Immunology, 23(7), 313-316.
- The immunologist cautioned Shanice that she may be more susceptible to virally induced cancers. Why did the immunologist state this? The immunologist warned Shanice about her susceptibility to virally induced cancers because natural killer cells play a crucial role in controlling viral infections and preventing the development of cancer. NK cells are involved in the immune surveillance of viral infections by directly killing virus-infected cells. They can recognize infected cells and eliminate them before the virus has a chance to replicate and spread further.
In the absence of functional NK cells, Shanice’s immune system may have difficulty controlling viral infections, which can lead to persistent or chronic viral infections. Some viruses, such as human papillomavirus (HPV), Epstein-Barr virus (EBV), or hepatitis B and C viruses, are known to be associated with an increased risk of developing certain types of cancers. Without the efficient clearance of virus-infected cells by NK cells, the risk of developing virally induced cancers may be elevated.
Scholarly resource: Source: Vivier, E., Tomasello, E., Baratin, M., Walzer, T., & Ugolini, S. (2008). Functions of natural killer cells. Nature Immunology, 9(5), 503-510.
- What treatments or other options does Shanice have to counteract the natural killer cell deficiency? The treatment options for Shanice’s natural killer cell deficiency depend on the underlying cause and severity of the deficiency. In some cases, if a specific cause is identified, treating the underlying condition or addressing any associated infections may improve NK cell function.
If Shanice has a primary immunodeficiency disorder affecting NK cells, she may benefit from immunoglobulin replacement therapy or other immune-modulating treatments. In some cases, hematopoietic stem cell transplantation (HSCT) may be considered to restore normal immune function, but this is typically reserved for severe and life-threatening cases.
Additionally, there are ongoing research and clinical trials exploring the use of NK cell-based therapies, such as adoptive NK cell transfer or the administration of cytokines that enhance NK cell activity, to boost the immune response in individuals with NK cell deficiencies. However, it’s important to consult with a specialized immunologist who can evaluate Shanice’s specific condition and provide personalized treatment recommendations.
Scholarly resource: Source: Ito, M., & Marques, L. (2014). Natural killer cell deficiency. Journal of Allergy and Clinical Immunology, 134(4), 850-855.