Question

HIV causes immune deficiency because the virus a. destroys all the cytotoxic T cells. b. preferentially destroys helper T cells that regulate the immune system. c. directly inactivates plasma cells. d. causes mutations that lead to autoimmune diseases. e. causes helper T cells to multiply uncontrollably.

Short answer

The correct answer is b. HIV preferentially destroys helper T cells that regulate the immune system.

Step-by-step solution

HIV and the Immune System

HIV, or Human Immunodeficiency Virus, is known for causing AIDS (Acquired Immunodeficiency Syndrome) which is a condition in humans where the immune system begins to fail, leading to life-threatening opportunistic infections. The virus primarily attacks certain cells in the immune system, rendering it less effective in dealing with other pathogens.

Recognizing Main Targets of HIV

HIV specifically targets cells in the immune system called T-cells or T-lymphocytes. Among them, the virus mainly targets a type of T-cell known as CD4 or Helper T-cell.

Understanding the Role of Helper T cells

Helper T cells have a crucial role in regulating the immune responses by instructing other cells in the immune system to perform their functions. They stimulate B cells to produce antibodies and cytotoxic T cells to kill infected target cells.

Effects of HIV on Helper T cells

HIV infects and destroys Helper T cells. The progressive loss of these cells in individuals infected by HIV leads to a weakened immune system. This makes the individuals more prone to infections and diseases that the body would have usually been able to fend off.

Eliminating Incorrect Options

With that understanding, it's clear which of the answer choices are incorrect. Option a is wrong because HIV does not destroy all the cytotoxic T cells. Option c is incorrect because HIV doesn't directly inactivate plasma cells. Option d is also out of consideration because HIV does not cause mutations leading to autoimmune diseases. Finally, option e is wrong because HIV does not cause Helper T cells to multiply uncontrollably.

Key concepts

Helper T cells function

Helper T cells, also known as CD4+ T cells, are pivotal in maintaining a robust immune system. They act as coordinators in the body's defense mechanism, signaling other immune cells to carry out their specialized roles. When a pathogen invades the body, it is the job of helper T cells to recognize this threat and swiftly activate the immune army. They mobilize B cells to produce antibodies, critical proteins that latch onto foreign invaders, marking them for destruction. Helper T cells additionally stimulate cytotoxic T cells, the 'assassins' of infected cells, ensuring that any cells harboring pathogens are eradicated.

Without the guiding influence of helper T cells, the immune response can become disorganized, much like an orchestra without its conductor. B and cytotoxic T cells rely heavily on instructions from helper T cells to function correctly. Therefore, the health and functionality of helper T cells are indispensable for a well-regulated and efficient immune system.

Pathophysiology of HIV

Human Immunodeficiency Virus, or HIV, is a retrovirus that specifically targets and infiltrates helper T cells. Understanding the pathophysiology of HIV is key to comprehending its devastating effect on the immune system. Once HIV enters the bloodstream, it seeks out the CD4 molecule on the surface of helper T cells and uses it as a gateway to infiltrate the cell. Inside, the virus hijacks the cell's machinery to replicate itself, producing new viral particles.

As these new viruses burst forth from the host cell, they destroy it in the process. This loss of helper T cells impairs the immune system's ability to mount an effective response to infections. Chronically, the body becomes less capable of defending itself against 'opportunistic' infections—diseases that are typically non-threatening but can become life-threatening when the immune system is weakened by HIV. Individuals with HIV thus find it increasingly difficult to recover from even minor infections as the virus progresses, potentially leading to Acquired Immunodeficiency Syndrome (AIDS).

Immune response regulation

Regulation of the immune response is a complex and finely tuned process, crucial for preventing infections and maintaining health. It involves a balanced orchestration of immune cell types, including helper T cells, B cells, cytotoxic T cells, macrophages, and others. Each cell type has a specific role in identifying, targeting, and eliminating pathogens such as bacteria, viruses, and fungi.

The immune system also needs to differentiate between harmless and harmful substances, a process where regulation is critical to avoid autoimmune disorders. Here, the importance of helper T cells is emphasized again—they produce cytokines, which are signalling molecules that regulate the intensity and duration of the immune response. If the immune system is too active, it may attack the body's own tissues, resulting in autoimmune diseases. Conversely, if the immune response is too weak, as seen in untreated HIV infection, the body becomes vulnerable to ordinary infections. Thus, the fine-tuning provided by helper T cells is not only essential for fighting off infections but also for preventing the immune system from turning against the body itself.