Lymphocyte Subset Panel 4
This blood test panel measures key lymphocyte subsets (T, B, and NK cells) to help interpret immune deficiency, activation, and inflammation patterns.
This panel bundles multiple biomarker tests in one order—your report explains how results fit together.
This is a lab panel, not a single marker. Lymphocyte Subset Panel 4 uses flow cytometry to count and characterize major immune cell groups in your blood—especially T cells, B cells, and natural killer (NK) cells—so you can see whether your immune system looks underpowered, overactivated, or imbalanced.
Do I need this panel?
You may consider Lymphocyte Subset Panel 4 if you are trying to make sense of recurring infections, slow recovery from illnesses, unusual fatigue, persistent swollen lymph nodes, or chronic inflammation symptoms that do not have a clear explanation.
This panel is also commonly used when you have autoimmune concerns (for example, a positive ANA with ongoing symptoms) and you want more context about immune activation or immune depletion patterns. It can be helpful when you are evaluating possible immunodeficiency, monitoring immune effects of certain medications, or following up on abnormal blood counts.
Because this is a multi-marker panel, it is most useful when you plan to interpret the results together rather than focusing on one number. Your results should support clinician-directed care and decision-making, not self-diagnosis.
Lymphocyte subsets are typically measured by flow cytometry on whole blood; reference ranges and flags can vary by lab, age, and clinical context.
Lab testing
Ready to order Lymphocyte Subset Panel 4?
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this panel with Vitals Vault
Vitals Vault lets you order Lymphocyte Subset Panel 4 as a single lab panel so you can get a structured snapshot of key immune cell populations from one blood draw.
After your results post, you can use PocketMD to translate the pattern across the panel into plain language—what looks low, what looks high, and what combinations tend to suggest immune suppression, immune activation, or recovery after a recent illness.
If you are building an immune workup, this panel can be paired with complementary testing (for example, immunoglobulins such as IgG, IgA, IgM, and IgE) to compare cellular immunity (lymphocytes) with humoral immunity (antibodies). Retesting can also be useful when you and your clinician are tracking trends over time rather than reacting to a single snapshot.
- Single blood draw with multiple immune cell measurements reported together
- Designed for pattern-based interpretation (not one isolated value)
- PocketMD support for questions about your specific result combinations
- Useful for trending when repeated on the same lab method
Key benefits of Lymphocyte Subset Panel 4
- Shows whether low or high total lymphocytes are driven by T cells, B cells, NK cells, or a mix.
- Helps contextualize recurrent infections by identifying patterns consistent with cellular immune deficiency.
- Adds immune-cell detail that a standard CBC differential cannot provide.
- Supports autoimmune and chronic inflammation workups by highlighting activation-leaning patterns (for example, shifted CD4/CD8 balance).
- Helps monitor immune effects of medications that can suppress or reshape lymphocyte populations.
- Improves interpretation of borderline results by pairing absolute counts with percentages across subsets.
- Creates a baseline you can trend over time to separate temporary illness effects from persistent immune imbalance.
What is the Lymphocyte Subset Panel 4 panel?
Lymphocyte Subset Panel 4 is a blood test panel that breaks your lymphocytes into major functional groups and reports them as both percentages and absolute counts. Lymphocytes are white blood cells that coordinate immune defense, immune memory, and immune regulation.
Most panels in this family are performed using flow cytometry, a method that tags cells with antibodies against surface markers (often called “CD markers”) and then counts how many cells carry each marker pattern. Instead of telling you only “your lymphocytes are low” or “your lymphocytes are high,” this panel helps answer a more practical question: which immune cell compartments are driving the change?
In plain terms, the panel focuses on:
• T cells (often CD3+), which include helper T cells (CD4+) and cytotoxic T cells (CD8+). These cells are central to antiviral defense, immune regulation, and coordination of other immune responses.
• B cells (often CD19+ or CD20+), which mature into plasma cells that produce antibodies and support immune memory.
• Natural killer (NK) cells (often CD16+/CD56+), which provide rapid responses to infected or abnormal cells.
Your report may include a CD4/CD8 ratio and may list results as “% of lymphocytes” and as “absolute” values (cells per microliter). Both matter: percentages can look normal even when the absolute cell count is low, and absolute counts can look normal even when the balance between subsets is shifted.
This panel does not diagnose a specific autoimmune disease or immunodeficiency on its own. It is a pattern tool that becomes more meaningful when combined with your symptoms, medication history, recent infections or vaccines, and companion labs (such as immunoglobulins, inflammatory markers, and sometimes viral testing).
What do my panel results mean?
Low results across the panel (or low absolute counts in key subsets)
A “low” pattern usually means one or more lymphocyte compartments are reduced on an absolute basis (not just a lower percentage). If multiple subsets are low at the same time, it can reflect recent viral illness, physiologic stress, steroid exposure, certain immune-modulating medications, or less commonly an underlying immunodeficiency. If T cells are disproportionately low, the question often becomes whether this is temporary suppression versus a persistent cellular immunity issue. If B cells are notably low, clinicians often consider medication effects and may pair results with immunoglobulins to see whether antibody production is also affected. The most useful next step is usually to look for consistency: do low absolute counts repeat on a second test when you are well and off short-term confounders?
Optimal results (balanced subsets with adequate absolute counts)
An “optimal” panel pattern generally means your absolute counts are within the lab’s reference intervals and the distribution between T cells, B cells, and NK cells looks proportionate for your age and context. A balanced CD4/CD8 ratio and stable absolute counts tend to support the idea that your cellular immune system has adequate capacity and is not showing a strong signal of depletion or reactive expansion. Even with an overall reassuring panel, symptoms can still come from non-lymphocyte pathways (for example, neutrophil-driven inflammation, endocrine issues, iron deficiency, sleep disruption, or medication side effects). In that situation, the panel is still valuable because it helps narrow the search and prevents over-interpreting a single immune marker.
High results across the panel (or high counts in specific subsets)
A “high” pattern can mean your immune system is responding to something—often recent infection, chronic antigen exposure, inflammation, smoking, or physiologic stress. Sometimes the elevation is driven mainly by one compartment (for example, higher T cells with a CD8-leaning shift after viral exposure, or higher B-cell percentages in certain inflammatory states). High percentages can also appear when another subset is low, so absolute counts help clarify whether you truly have expansion or just a relative shift. Persistently high or progressively rising counts—especially when paired with symptoms like fevers, night sweats, unintentional weight loss, or persistent lymph node enlargement—should be reviewed promptly with a clinician to decide whether additional evaluation is needed.
Factors that influence lymphocyte subset patterns
Your panel results are sensitive to timing and context. Recent infections (especially viral), vaccines, intense exercise, sleep deprivation, and acute stress can shift T-cell and NK-cell distributions for days to weeks. Medications are a major driver: corticosteroids, chemotherapy, biologics, and other immune-modulating therapies can lower specific subsets or change the CD4/CD8 balance. Age, pregnancy/postpartum status, smoking, and chronic conditions can also affect reference ranges and typical patterns. Finally, interpretation depends on whether you are looking at percentages, absolute counts, or both—an apparent “high percentage” can occur simply because another subset is reduced. If your results are confusing, it often helps to review them alongside a CBC with differential, inflammatory markers, and (when relevant) immunoglobulins.
What’s included in this panel
- Absolute Cd4+ Cells
- Absolute Cd8+ Cells
- Absolute Lymphocytes
- % Cd4
- Cd4/Cd8 Ratio
- % Cd8
Frequently Asked Questions
Do I need to fast for Lymphocyte Subset Panel 4?
Fasting is not usually required for lymphocyte subset testing. If you are combining this panel with other labs (like lipids or glucose/insulin testing), fasting rules may come from those tests instead. Follow the collection instructions provided with your order.
Why does this panel report both percentages and absolute counts?
Percentages describe the balance between immune cell groups, while absolute counts reflect how many cells are actually present in a given blood volume. A percentage can look “normal” even when the absolute count is low (and vice versa), so reading both together reduces misinterpretation.
What is flow cytometry, and why is it used for lymphocyte subsets?
Flow cytometry is a lab method that labels blood cells with fluorescent tags that bind to specific surface markers (CD markers). The instrument then counts and categorizes cells based on those markers, which is how T cells, B cells, and NK cells are separated and quantified.
Can this panel diagnose an autoimmune disease like lupus?
This panel does not diagnose lupus or other autoimmune diseases on its own. It can provide supportive context (for example, patterns suggesting immune activation or immune suppression), but diagnosis typically relies on symptoms, exam findings, and disease-specific antibodies and complement testing.
How should I think about a “low” result if I recently had a cold or vaccine?
Recent infections and vaccines can temporarily shift lymphocyte counts and subset balance. If a result is mildly abnormal and you were recently sick or vaccinated, clinicians often consider repeating the panel when you are back to baseline to see whether the pattern persists.
Is it better to order this panel or individual CD4/CD8 tests separately?
A panel is usually more informative because it shows the full distribution across major lymphocyte groups and includes both percent and absolute values in one report. Ordering a single subset in isolation can miss the broader pattern that explains why the number is abnormal.
Should I add immunoglobulin testing (IgG, IgA, IgM, IgE)?
Often, yes—especially if you are evaluating recurrent infections or suspected immunodeficiency. Lymphocyte subsets describe cellular immunity, while immunoglobulins reflect antibody availability. Together, they give a more complete picture of immune function and can guide more targeted follow-up.