Which immunity is affected by HIV infection?

AIIMS Raipur - 2017 (Shift-3)

Applied Microbiology & Infection control

Easy

Appeared in: AIIMS Raipur - 2017 (Shift-3)

Explanation

The Human Immunodeficiency Virus (HIV) selectively targets cells with CD4 receptors on their surface.
The primary cell targeted by HIV is the CD4+ T-lymphocyte, also known as the T-helper cell.
These T-helper cells are the main coordinators of the adaptive immune response, specifically cell-mediated (cellular) immunity.
By destroying CD4+ cells, HIV cripples the cellular immune system, leading to immunodeficiency.
The decline in cellular immunity is what makes individuals with advanced HIV (AIDS) susceptible to opportunistic infections.

Option A: Natural (or innate) immunity is the body's non-specific, first line of defense (e.g., skin, stomach acid). While HIV must bypass these barriers, it does not primarily target or destroy the components of the innate immune system.
Option B: Active immunity is a broad term for immunity developed after exposure to an antigen (either through infection or vaccination). It encompasses both cellular and humoral immunity. While HIV affects active immunity, 'Cellular immunity' is the more specific and correct answer as it identifies the precise branch that is most severely damaged.
Option D: Humoral immunity, which involves B-cells and antibodies, is affected by HIV, but indirectly. B-cells require activation signals from CD4+ T-helper cells to produce antibodies effectively. As HIV destroys T-helper cells, the humoral response weakens. However, the primary site of attack is the T-cell, the core of cellular immunity.

Visual 1: Diagram: HIV virus binding to the CD4 receptor on a T-helper cell, showing viral entry and replication, ultimately leading to cell death.
Visual 2: Flowchart: Depicting the central role of the CD4+ T-helper cell in activating both cytotoxic T-cells (cellular immunity) and B-cells (humoral immunity), and how its destruction by HIV disrupts both pathways.
Visual 3: Graph: Showing the typical progression of HIV infection over time, with lines illustrating the decline in CD4+ cell count and the corresponding rise in viral load.

Clinical Relevance

Nursing practice connection: Knowing Pathophysiology of HIV and its effect on the immune system helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A nurse's primary role in caring for a patient with HIV is to monitor for signs of immunosuppression and opportunistic infections, which are direct consequences of failed cellular immunity.
Understanding that cellular immunity is compromised explains why patients with low CD4 counts are at high risk for fungal infections (like Pneumocystis pneumonia, Candidiasis), viral infections (like CMV), and certain cancers (like Kaposi's sarcoma).
Patient education is critical. Nurses must teach patients the importance of adherence to antiretroviral therapy (ART) to suppress the virus, preserve CD4+ cells, and maintain cellular immune function.

How to Approach the Question

First, identify the core subject of the question: the effect of HIV on the immune system.
Recall the specific pathogen (HIV) and its primary target cell in the human body. You should remember that HIV targets CD4+ T-cells.
Next, classify the target cell within the branches of the immune system. CD4+ T-cells are the key players in cell-mediated, or cellular, immunity.
Evaluate the given options. 'Cellular immunity' directly corresponds to the system involving T-cells.
Consider the other options to confirm your choice. 'Humoral immunity' is a strong distractor, but it is affected secondarily. 'Natural' and 'Active' are either incorrect or too general.
Select the option that names the specific immune branch directly and most severely damaged by the virus.

Concept Tested & Keywords

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