Outline how HIV affects the immune system, limited to: decreased lymphocyte numbers and reduced ability to produce antibodies, which weakens the immune system

SouravNovember 3, 2024

Answered step-by-step

HIV (Human Immunodeficiency Virus) significantly impacts the immune system, primarily through decreased lymphocyte numbers and a reduced ability to produce antibodies. This weakening of the immune system leads to increased susceptibility to infections and diseases. Here’s an outline of how HIV affects these aspects:

1. Decreased Lymphocyte Numbers

• CD4+ T Cells: HIV primarily targets and infects CD4+ T lymphocytes, which are crucial for orchestrating the immune response. As the virus replicates, it destroys these cells, leading to a gradual decline in their numbers.
• Impact on Immune Function: The depletion of CD4+ T cells compromises the immune system’s ability to respond effectively to infections. A significant drop in CD4+ T cell counts (below 200 cells/mm³) is a hallmark of progression toward AIDS (Acquired Immunodeficiency Syndrome), where the body becomes highly vulnerable to opportunistic infections and certain cancers.

2. Reduced Ability to Produce Antibodies

• Impaired B Cell Function: The infection does not only affect T cells; it also impairs B lymphocytes, which are responsible for producing antibodies. Studies have shown that individuals with HIV experience defects in B cell activation and differentiation, leading to a diminished antibody response.
• Poor Vaccine Responses: HIV-infected individuals often exhibit reduced efficacy in vaccine responses due to their compromised ability to produce specific antibodies. This includes lower titers of antibodies against pathogens that would normally elicit a strong immune response in healthy individuals.
• Chronic Immune Activation: The persistent presence of HIV leads to chronic immune activation, which can exhaust B cells and further diminish their functionality. This results in fewer effective antibodies being produced, limiting the body’s ability to combat infections.