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Lab panel

Lymphocyte Subset Panel 4 Test

The Lymphocyte Subset Panel 4 measures CD4+ and CD8+ T cell counts and calculates their ratio from a blood sample. Quest describes it as providing information on immune status, particularly in HIV infection.

Blood drawQuest patient service center

About this panel

This panel reports on two types of T cells, CD4+ and CD8+, and the ratio between them. Quest describes CD4 count as the most valuable indicator of immune status in HIV-infected individuals, while CD8 count reflects the level of immune activation in response to HIV.

The sample is analyzed with flow cytometry, a laboratory method that identifies and counts specific cell types. Quest notes that CD4 count and the CD4/CD8 ratio typically decline after seroconversion while CD8 levels increase, and that persistently elevated CD8 counts after treatment have been linked to increased risk of certain non-AIDS-defining diseases.

Who might consider this panel?

  • Often establishing a baseline for immune status
  • Tracking antiretroviral treatment progress
  • Evaluating helper and suppressor cell immune status in the context of another immunodeficiency condition

Test details

Quest code7924
MethodologyFlow Cytometry
Sample type5 mL whole blood
CollectionQuest patient service center

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Quest resources

Additional details

What this test looks at

The panel reports the percentage and absolute count of CD4+ cells, the percentage and absolute count of CD8+ cells, absolute lymphocytes, and the CD4/CD8 ratio. Quest also lists 'Flow' as an alias for this panel, reflecting the flow cytometry method used.

Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does the Lymphocyte Subset Panel 4 measure?

It measures CD4+ and CD8+ T cell counts and calculates their ratio, using flow cytometry on a whole blood sample.

How is the sample collected?

The test uses a whole blood sample, collected in an EDTA tube, from a routine blood draw.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

Why is this panel used with HIV infection?

Quest describes CD4 count as the most valuable indicator of immune status in HIV-infected individuals and CD8 count as reflecting the level of immune activation in response to HIV, which is why the panel is used to establish baselines and track treatment progress.

Can I get the Lymphocyte Subset Panel 4 test without a doctor's visit or insurance?

Yes. The $200 cash price includes an independent physician's order, so no referral is needed, and insurance is never involved.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.