Most HIV-negative adults have between 500 and 1500 CD4 cells in a cubic millimeter of blood. However, due to natural variation some people may have a CD4 count slightly outside the general range. It can vary by around 100 cells below the lower or above the higher end without any health implications.
CD4 cells are a subset of our immune system that are essential for the teamwork of all other immune cells. They help the other immune cells to launch a well-coordinated attack when there is an intruder such as a virus, bacterium, and the like. CD4s tell the other cells who the intruder is, where to look for it, what tools to use against it, and when to stop.
Our genetic makeup, age and health status have the greatest influence on our CD4 count. However, certain medications and substance use can equally have a measurable effect. What is more, the CD4 count measurement is only a momentary snapshot. Our numbers can vary depending on the time of day (lower in the morning), our nutritional status, and stress levels. Often doctors may order an additional test to check the percentage of CD4 cells which is usually more stable over time.
