HIV destroys CD4 T lymphocytes (helper T cells). Because of this, healthcare professionals measure CD4 levels to monitor HIV progression and AIDS.
Helper T cells are crucial for immune system function and activate after encountering antigens from disease-causing microorganisms. Antigens are biological markers that identify microorganisms such as bacteria and viruses.
Keep reading to learn more about T cells and their function and the link between T cell level and HIV and AIDS.
T cells grow from stem cells in the bone marrow. They are a type of white blood cell. There are
Helper T cells
Macrophages are another type of white blood cell. They consume disease-causing microorganisms, or pathogens, then present fragments of their antigens to helper T cells. When a helper T cell binds to the antigen fragment that it recognizes, it activates and alerts other white blood cells to the pathogen.
Helper T cells have CD4 proteins on their cell surface, which help them bind to antigen fragments. Because HIV destroys helper T cells, healthcare professionals use a CD4 count
Killer T cells
After receiving the alert, killer T cells seek out and destroy the pathogen (virus, bacteria, or disease-causing microorganisms). Other white blood cells, such as B lymphocytes, will also activate and produce antibodies in order to protect against the threat.
HIV enters its genetic information into helper T cells to make copies of itself. When this happens, the helper T cells die. This severely disrupts the immune response. Low levels of helper T cells mean killer T cells and other white blood cells do not receive as much information about pathogens in the body. As a result, disease-causing bacteria and viruses multiply with minimal detection.
When the amount of helper T cells falls below
AIDS is the most severe stage of HIV. When a person receives an AIDS diagnosis, their immune system is severely compromised, and they are at risk for opportunistic illnesses. The survival rate without treatment at this stage is typically
CD4 T cells are helper T cells. They express, or manifest, a CD4 protein on their cell surface that
When activated, helper T cells mobilize other white blood cells to initiate a full immune response. Killer T cells, for example, then seek out the pathogen and destroy it by releasing granzymes, which
If someone’s helper T cells are below
When a person has HIV, a healthcare professional will collect a blood sample and request a CD4 count. The CD4 count helps determine how many helper T cells a person has.
But when analyzing a CD4 count, healthcare professionals must take into account that:
- CD4 levels could be lower in the morning
- stress and fatigue may affect CD4 levels
- corticosteroid levels could increase or decrease CD4 levels
All people whose helper T cells are below 200 cells/mm3 should receive a CD4 count every 3–6 months. If treatment is working, a person may only need a CD4 checkup every 6–12 months.
The CD4 count helps healthcare professionals monitor HIV progression and if the person is at risk for opportunistic illnesses.
When a healthcare professional wants a CD4 count, they take a blood sample from a person’s arm.
Side effects of drawing blood may include:
- mild bruising
- feeling faint
A healthcare professional will likely only need to draw a small amount of blood, so a person should not feel any significant side effects.
Usually, when someone receives an HIV diagnosis, they will start antiretroviral therapy (ART)
If a person responds well to ART, their CD4 levels may increase by
After analyzing a CD4 count, a healthcare professional can determine if the current care plan is working or if they need to introduce additional treatments.
As soon as CD4 levels drop below 200 cells/mm3, a healthcare professional may need to increase ART and administer other drugs to help bolster the immune system against opportunistic illnesses.
All people with HIV should receive a CD4 count every 3–6 months if their CD4 levels are below 200 cells/mm3, as this indicates a progression to AIDS. If the treatment is working and the CD4 count is stable, a person may only need a checkup every 6–12 months.
If a person receives an HIV diagnosis in time and starts ART
Taking ART not only keeps the volume of helper T cells high but also decreases the viral load (the amount of virus in the body).
If someone’s viral load decreases, it may reach an undetectable level. This means if a person keeps up the treatment for their condition, the virus cannot transmit to anyone through sex. Having an undetectable viral load also reduces HIV transmission during birth.
A healthcare professional requests a CD4 count to monitor helper T cell levels. When a person’s CD4 levels drop below
T cells include two main types: helper T cells and killer T cells. Helper T cells express a CD4 protein on their cell surface that helps them bind to antigen fragments. These antigen fragments belong to disease-causing viruses and bacteria. After binding, the helper T cells signal other white blood cells to destroy the pathogen. Killer T cells are another type of T cell that break down pathogens by releasing granzymes that