CD4/CD8 Ratio

immunohematologyImmunity & InflammationBlood

The CD4 to CD8 ratio T-cell test compares the number of helper T cells to the number of cytotoxic T cells. Helper T cells are also called CD4+ cells, and rather than killing cells directly they send signals that tell other cells in the immune system how to coordinate an attack against invaders. Cytotoxic T cells are also called CD8+ cells, and they kill cells infected with viruses and bacteria as well as destroying tumour cells.

Why it matters: A provider may order a T cell count, also called a CD4 count, if they suspect there is an issue with the immune system. Or they may order a CD4 to CD8 ratio T-cell test, to see how many helper T cells there are in relation to cytotoxic T cells.

Source · Cleveland Clinic — what it is, why it matters

Related Markers
cd4_countcd8_count
Common questions

What is CD4/CD8 Ratio?

The CD4 to CD8 ratio T-cell test compares the number of helper T cells to the number of cytotoxic T cells. Helper T cells are also called CD4+ cells, and rather than killing cells directly they send signals that tell other cells in the immune system how to coordinate an attack against invaders. Cytotoxic T cells are also called CD8+ cells, and they kill cells infected with viruses and bacteria as well as destroying tumour cells.

What might a high or low CD4/CD8 Ratio mean?

A provider may order a T cell count, also called a CD4 count, if they suspect there is an issue with the immune system. Or they may order a CD4 to CD8 ratio T-cell test, to see how many helper T cells there are in relation to cytotoxic T cells.

More in immunohematology
ABO Blood GroupAbsolute CD4 Helper CellsAbsolute CD8 Suppressor CellsImmunoglobulin EPercentage of CD4 Positive LymphocytesPercentage of CD8 Positive LymphocytesRh(D) Blood GroupRheumatoid Factor

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