Extreme leukopenia (a severe decrease in the number of white blood cells) in individuals infected with HIV is primarily caused by the virus's direct impact on the immune system. HIV attacks and destroys CD4+ T cells, which are a type of white blood cell that plays a crucial role in the immune response. As the virus replicates and destroys these immune cells, the body's ability to fight off infections is severely compromised.
Leukopenia, specifically a decrease in the number of CD4+ T cells, is a hallmark of HIV infection and is one of the defining criteria used to assess the progression of the disease. As the immune system weakens due to the loss of CD4+ T cells, individuals become more susceptible to opportunistic infections, which are typically controlled by a healthy immune system but can become severe in those with HIV.
To manage HIV and prevent extreme leukopenia, antiretroviral therapy (ART) is often prescribed. ART can help suppress the replication of the virus, slow down the progression of the disease, and partially restore the immune system's function by increasing CD4+ T cell counts. However, in advanced stages of HIV infection or without access to treatment, extreme leukopenia and a compromised immune system can leave individuals vulnerable to various infections and health complications.