**Question:** HIV virus primarily affects which immune system cells?

**Core Concept:** Human Immunodeficiency Virus (HIV) is the virus responsible for Acquired Immune Deficiency Syndrome (AIDS). HIV primarily targets specific immune system cells, which are crucial for maintaining immune function and combating infections.

**Why the Correct Answer is Right:** HIV primarily attacks CD4+ T cells, also known as helper T cells or T4 cells. These cells play a critical role in coordinating the immune response against pathogens, such as bacteria, viruses, and parasites. By destroying CD4+ T cells, HIV weakens the immune system, making the infected individual more susceptible to various infections and cancers.

**Why Each Wrong Option is Incorrect:**

A. **HIV does not primarily affect B cells (B-lymphocytes). Although B cells are also crucial for immune response, they are not the primary target of HIV.**

B. **HIV does not primarily affect Natural Killer (NK) cells. While NK cells are involved in immune response, they are not the main focus of HIV infection.**

C. **HIV does not primarily affect Monocytes and Dendritic cells. Although these cells are part of the immune system, CD4+ T cells are the main focus of HIV infection.**

D. **HIV does not primarily affect Neutrophils. Neutrophils are part of the innate immune system and are not the primary target of HIV.**

**Clinical Pearl:** HIV primarily targets CD4+ T cells, which is why it is crucial to maintain a healthy lifestyle to prevent HIV transmission and protect the immune system. This includes using condoms during sexual activities, avoiding sharing needles or other injection drug use, and being aware of potential exposure through contaminated blood products.

**Correct Answer:** D. HIV primarily affects CD4+ T cells, also known as T-helper cells, which are involved in coordinating the immune response against pathogens. By attacking these cells, HIV weakens the immune system and leads to AIDS.