What is the main target cell for HIV entry in the immune system?

AIIMS CRE 2025

Applied Microbiology & Infection control

Easy

Appeared in: AIIMS CRE 2025

Explanation

The Human Immunodeficiency Virus (HIV) primarily infects CD4+ T cells, also known as T-helper cells.
Viral entry is mediated by the binding of the HIV envelope protein gp120 to the CD4 receptor and a co-receptor (CCR5 or CXCR4) on the surface of the T-helper cell.
CD4+ T cells are central to coordinating the adaptive immune response; their progressive destruction by HIV leads to severe immunodeficiency.
The depletion of CD4+ T cells is the hallmark of HIV disease progression to Acquired Immunodeficiency Syndrome (AIDS).

Option A: CD8 T cells are cytotoxic 'killer' cells that are part of the immune response against HIV-infected cells, not the primary target for viral entry.
Option C: B cells produce antibodies and are not the main target for HIV infection. Their function is impaired indirectly due to the loss of 'help' from CD4 T cells.
Option D: Neutrophils are phagocytes of the innate immune system, primarily fighting bacterial infections. They lack the CD4 receptor and are not a target for HIV.

Visual 1: Diagram: HIV viral entry into a CD4 T cell. This visual should clearly label the HIV virus, its gp120 protein, the host cell's CD4 receptor, and the co-receptor (CCR5 or CXCR4), illustrating the lock-and-key mechanism of infection.
Visual 2: Chart: Progression of HIV infection over time. This chart should graph the inverse relationship between the rising viral load and the declining CD4 T cell count in an untreated individual, with a line indicating the 200 cells/mm³ threshold for an AIDS diagnosis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of HIV and its primary cellular target in the immune system as background academic context rather than a clinical decision trigger.
Monitoring CD4 T cell counts is a fundamental nursing responsibility in HIV care. It directly informs clinical decisions regarding the initiation of Antiretroviral Therapy (ART) and prophylaxis for opportunistic infections.
A CD4 count below 200 cells/mm³ is a critical threshold that defines an AIDS diagnosis. This triggers the need for patient education on heightened infection risk and the initiation of preventive medications for conditions like Pneumocystis pneumonia (PJP).
Patient education regarding the meaning of their CD4 count is crucial for promoting adherence to ART. Nurses can explain that taking medication consistently helps preserve these vital immune cells.

How to Approach the Question

First, identify the key terms in the question: 'main target cell,' 'HIV,' and 'immune system.' This frames the question as a specific knowledge point in pathophysiology.
Recall the fundamental mechanism of HIV. The virus is named for the immunodeficiency it causes. This implies it must attack a critical controlling component of the immune system.
Analyze the options based on their primary immune functions: CD4 T cells are 'helpers,' CD8 T cells are 'killers,' B cells make antibodies, and neutrophils are phagocytes for bacteria.
Connect the disease (immunodeficiency) to the cell function. A deficiency in the 'helper' cell (CD4 T cell) would logically cripple the entire immune response, which matches the clinical presentation of AIDS.
Therefore, select the option representing the central coordinating cell of the adaptive immune system, which is the CD4 T cell.

Concept Tested & Keywords

Concept Tested: Pathophysiology of HIV and its primary cellular target in the immune system.
Stem keywords: HIV, immune system, main target cell, entry
Lead-in keywords: What is

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