CD1656 are an important NK (Natural killer) cell subset.

- NK cells are best known for killing virally infected cells, and detecting and controlling early signs of cancer. As well as protecting against disease, specialized NK cells are also found in the placenta and may play an important role in pregnancy.

- Natural killer T (NKT) cells represent a specialized T-cell population that is distinct from conventional T cells. They express an invariant T-cell receptor (TCR) that recognizes self and bacterial glycosphingolipid antigens presented by the MHC class I-like molecule, CD1d.

- Human natural killer (NK) cells can be subdivided in several subpopulations on the basis of the relative expression of the adhesion molecule CD56 and the activating receptor CD16. 

- NK cells serve an important role in host defense against viral infections, as well as tumor surveillance. They are also a component of the adaptive immune response through cytokine production.

- NK cell functions are governed by a balance between activating receptors and inhibitory receptors.

The marker "CD18 Expression (LAD 1)" on a Leukocyte Adhesion Deficiency (CD15s, CD18) panel from Quest Diagnostics is a crucial test for diagnosing Leukocyte Adhesion Deficiency Type 1 (LAD-1), a rare genetic disorder. In this condition, CD18, a protein that is part of a complex necessary for white blood cells (leukocytes) to adhere to and migrate through blood vessel walls during an immune response, is either missing or malfunctioning. CD18 expression is vital because it facilitates the process by which white blood cells exit the bloodstream to reach sites of infection, inflammation, or injury.

The CD19 antigen (aka B-lymphocyte antigen CD19 or Cluster of Differentiation 19) plays an important role in clinical oncology. It’s a protein found on the surface of B-cells, a type of white blood cell.

The CD19 antigen (aka B-lymphocyte antigen CD19 or Cluster of Differentiation 19) plays an important role in clinical oncology. It’s a protein found on the surface of B-cells, a type of white blood cell.

CD19+ B cells represent the full population of B lymphocytes in the bloodstream and serve as a core measure of B-cell health. Because CD19 is expressed on nearly all B-cell stages (from early B cells to mature B cells), this marker provides essential insight into immune competence, antibody production capacity, and potential immune dysregulation.

CD19+ B Cells % reflects the proportion of lymphocytes that belong to the B-cell lineage. Because CD19 is expressed across nearly all stages of B-cell development, this percentage helps clinicians understand the balance between B cells and other lymphocyte types, offering insights into immune regulation, inflammation, and potential B-cell disorders.

CD19+CD27+IgM+IgD+ refers to a specific subset of B cells characterized by the expression of the cell surface markers CD19, CD27, IgM, and IgD. These markers help categorize B cells into different subsets based on their developmental stage and function.

In this context, the percentage of CD19+CD27+IgM+IgD+ cells (% of CD27+) likely refers to the proportion of B cells with this specific phenotype within the total CD27+ B cell population. It represents a subset of memory B cells with unique characteristics.

Naive B cells CD19+CD27-CD21-CD38- are a specific subset of B cells with distinct surface marker characteristics:

• CD19+: This marker indicates that these cells express the CD19 antigen, which is commonly found on B cells.

• CD27-: The absence of CD27 expression suggests that these B cells are not memory B cells. CD27 is typically expressed on memory B cells.

• CD21-: The absence of CD21 expression may indicate that these B cells have reduced levels of complement receptor 2 (CR2), which can affect their ability to respond to complement-mediated signals.

• CD38-: The absence of CD38 expression suggests that these B cells have lower levels of CD38, which is involved in various B cell functions, including activation and differentiation.

Naive B cells, characterized as CD19+CD27-IGM+IGD+, are a subset of B cells that have not yet encountered an antigen. Here's a breakdown of their characteristics:

• CD19+: This marker signifies that these cells express the CD19 antigen, which is a common B cell marker.

• CD27-: Naive B cells lack CD27 expression. CD27 is a marker used to distinguish between memory B cells and naive B cells. The absence of CD27 indicates that these B cells have not undergone the differentiation and class-switching that typically occurs in memory B cells.

• IGM+ and IGD+: Naive B cells express both IgM and IgD immunoglobulin isotypes on their surface. IgM and IgD are B cell receptors and are important for antigen recognition. Naive B cells carry both to allow them to respond to a wide range of antigens effectively.

CD20+ B cells include the subset of B lymphocytes that express the CD20 antigen, a marker found on most mature B cells but absent on early precursors and antibody-secreting plasma cells. Measuring CD20+ cells helps clinicians evaluate B-cell maturation, immune system balance, and the impact of immunotherapies such as rituximab that selectively target CD20.

CD20 is a critical surface marker predominantly expressed on B lymphocytes from the late pre-B cell stage to memory B cells, absent on pro-B cells and plasma cells. The CD20+ % marker measures the proportion of B cells expressing CD20, aiding in disease monitoring, treatment assessment, and immune status evaluation. Abnormal levels can indicate conditions like chronic lymphocytic leukemia, non-Hodgkin lymphoma, or immunodeficiencies and are pivotal in tracking the efficacy of anti-CD20 therapies such as rituximab. Normal CD20+ % ranges vary, typically 5-15% of total lymphocytes or 95-100% when expressed as a percentage of CD19+ B cells. Deviations should be interpreted alongside other markers (e.g., CD19, CD22) and clinical context to guide diagnosis and treatment.

CD20 is a cell surface protein primarily expressed on the surface of B-cells, a type of white blood cell involved in the immune response. The CD20 molecule plays a critical role in the development, differentiation, and function of B-cells, which are responsible for producing antibodies. It acts as a calcium channel, helping regulate the flow of calcium ions into the cell, a process essential for B-cell activation and immune function. CD20 is not expressed on early B-cell precursors or on plasma cells, which means its expression is limited to specific stages in B-cell maturation.

Because CD20 is highly expressed on the surface of mature B-cells, it has become an important biomarker in diagnosing and treating various B-cell-related diseases, particularly B-cell non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL). These cancers are characterized by an abnormal proliferation of B-cells, and CD20 serves as a target for therapies designed to eliminate these malignant cells. Rituximab, an anti-CD20 monoclonal antibody, was one of the first therapeutic agents to target this protein, marking a significant advance in cancer treatment.

CD3+ cells are all T-lymphocytes, which includes both CD4+ and CD8+ lymphocyte cells.

This figure is rarely used for making treatment decisions.

CD3+/CD4+ % refers to the percentage of T-helper cells (a subtype of white blood cells) among all T-lymphocytes (T cells) in your blood. This marker is often measured as part of an immune panel using flow cytometry, especially in contexts involving immune system monitoring, such as HIV, autoimmune conditions, or immunodeficiency assessments.

Understanding the Components

• CD3+ T cells: Represent all mature T lymphocytes, a key part of the adaptive immune system.

• CD4+ T cells: A subset of CD3+ cells, often called T-helper cells, which coordinate immune responses by signaling other immune cells.

• CD3+/CD4+ %: The percentage of total T cells that are CD4+. This gives insight into the relative balance of helper T cells within the T cell population.

CD3+/CD4+, Abs stands for the absolute count of CD4+ T-helper cells within the total population of CD3+ T cells in the blood. This marker measures the exact number of helper T cells per microliter (μL) of blood, rather than just their percentage. It is a key indicator of immune system function, especially in the context of infections like HIV, immune deficiencies, and chronic inflammatory conditions.

The biomarker CD3+/CD4-/CD8- identifies a unique subset of T lymphocytes that express the CD3 surface protein but lack both CD4 and CD8 co-receptors. These cells are often referred to as double-negative T cells (DN T cells) due to their absence of CD4 and CD8 expression. DN T cells represent a small fraction of the total T cell population in peripheral blood, typically accounting for less than 5% of T cells.

The biomarker CD3+/CD4-/CD8- identifies a unique subset of T lymphocytes that express the CD3 surface protein but lack both CD4 and CD8 co-receptors. These cells are often referred to as double-negative T cells (DN T cells) due to their absence of CD4 and CD8 expression. DN T cells represent a small fraction of the total T cell population in peripheral blood, typically accounting for less than 5% of T cells.

CD3+/CD8+ % refers to the percentage of cytotoxic T cells (CD8+) among all T-lymphocytes (CD3+ cells) in your blood. This immune marker is measured using flow cytometry and is commonly included in T-cell subset panels to evaluate immune system status.

Understanding the Components

• CD3+ T cells: Represent all mature T lymphocytes, which are essential for adaptive immunity.

• CD8+ T cells: A subset of CD3+ cells, often called cytotoxic T cells, that directly kill infected or abnormal cells (like virus-infected cells or cancer cells).

• CD3+/CD8+ %: Indicates the proportion of cytotoxic T cells among total T cells, helping assess immune activation, suppression, or imbalance.

CD3+/CD8+, Abs refers to the absolute count of cytotoxic T cells (CD8+) within the population of total T cells (CD3+) in your blood. This test measures the number of CD8+ T cells per microliter (μL) of blood and is a critical marker for evaluating immune function, especially in viral infections, immune disorders, and after immune-modulating treatments.

Understanding the Components

• CD3+ T cells: Represent all mature T lymphocytes—key players in the adaptive immune system.

• CD8+ T cells: A subset of CD3+ T cells, known as cytotoxic T cells, that target and destroy virus-infected, cancerous, or otherwise abnormal cells.

• “Abs” (Absolute): Indicates the actual number of CD3+/CD8+ cells per microliter (μL) of blood, not just the percentage.

Why Is the Absolute CD3+/CD8+ Count Important?

The CD8+ absolute count provides important insight into:

• Immune activation during viral infections (e.g., HIV, CMV, EBV)

• T-cell immune surveillance and response

• Immune suppression or recovery following chemotherapy, transplant, or immunodeficiency

• Chronic inflammation or autoimmune disease activity

The CD3-/CD16+CD56+ (%) test is a sophisticated diagnostic assay crucial in the field of immunology, offering invaluable insights into the functioning of the body’s immune system. This test specifically measures the percentage of natural killer (NK) cells, identified by the absence of CD3 and the presence of CD16 and CD56 markers, in the total lymphocyte population. NK cells are a vital component of the innate immune system, playing a key role in the body’s first line of defense against tumors, virally infected cells, and in modulating immune responses. The CD3-/CD16+CD56+ (%) test is pivotal in evaluating various immune conditions, including autoimmune diseases, chronic viral infections, and certain cancers.