From the Guidelines
A decrease in CD4 count in an HIV patient is primarily caused by the progression of the disease, which can be influenced by various factors such as the virus itself, intercurrent illnesses, and certain medications.
Factors Affecting CD4 Count
- The virus: as the disease progresses, the virus continues to attack and destroy CD4 cells, leading to a decline in their count 1.
- Intercurrent illnesses: certain illnesses can affect CD4 cell counts, making it essential to consider these factors when interpreting CD4 cell counts 1.
- Medications: some medications can impact CD4 cell counts, and caution should be applied when interpreting these counts in patients taking such medications 1.
CD4 Count Monitoring
- The absolute CD4 cell count is commonly used to stage HIV disease and determine the need for prophylaxis against opportunistic infections and antiretroviral therapy 1.
- The CD4 cell percentage can also be used to assess immune function and is less variable than the absolute count, especially in children aged 5 years 1.
Treatment Considerations
- Initiating antiretroviral therapy is recommended for asymptomatic HIV-infected persons with a CD4+ T cell count of <350 cells/mm3 or a viral load of >55,000 copies/mL 1.
- For patients with CD4+ T cell counts >350 cells/mm3, both conservative and aggressive approaches to therapy can be considered, weighing the potential risks and benefits of initiating therapy 1.
From the Research
Causes of Decrease in CD4 Count
- HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production 2
- HIV preferentially infects HIV-specific CD4+ T cells, which can lead to a decrease in CD4 count 2
- Fibrosis of the T cell zone of lymphoid tissue can be an important factor in the failure to reconstitute T cells, leading to a decrease in CD4 count 3
- Certain antiretroviral therapies, such as tenofovir and didanosine, may contribute to a decrease in CD4 count 3
- Rest and normal daily activity can cause fluctuations in CD4 lymphocyte counts, with a significant decrease in CD4 count observed after 60 minutes of rest 4
- Severe respiratory tract infections can be associated with CD4 lymphocytopenia, even in the absence of HIV infection 5
Factors Contributing to CD4 Count Decrease
- HIV replication and antiretroviral drug resistance can contribute to a decrease in CD4 count, although this was not observed in all studies 3, 6
- Imbalance in CD4+ T-cell homeostasis can lead to a gradual loss of CD4+ T-cells and impairment of immunity 6
- Age and underlying health conditions, such as diabetes, malnutrition, or chronic kidney disease, may also contribute to a decrease in CD4 count, although this was not observed in all studies 5
Disease Progression and CD4 Count
- The rate of CD4+ T-cell decline can vary between HIV-1 and HIV-2 infections, with HIV-2 typically being less virulent and permitting a more effective and sustained T-cell immunity 6
- The progression of disease and decline in CD4 count can be influenced by various factors, including the effectiveness of antiretroviral therapy and the presence of underlying health conditions 3, 6