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

Sourav PanNovember 3, 2024

Answered

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.