Lymphocytes and Granulocyte-Monocyte Lineage Review

Comprehensive practice flashcards covering lymphocyte types, morphology, development, and the kinetics and functions of neutrophils, eosinophils, basophils, and monocytes based on Unit 3.1 and 3.2 lecture notes.

What is the absolute reference range for Lymphocytes in peripheral blood?

$1.0-3.2 \times 10^3/\mu\text{L}$ (or $1.0-3.2 \times 10^9/\text{L}$)

According to the transcript, what are the primary functions of lymphocytes?

1. Recognize and react with specific antigens; 2. Work with macrophages to eliminate pathogens; 3. Provide long-lasting immunity to previously encountered pathogens.

Which types of lymphocytes are primarily associated with cell-mediated immunity (CMI)?

T lymphs (effector and memory cells)

Which lymphocyte type is primarily responsible for humoral immunity?

B lymphs (effector and memory cells)

What is the primary function of Natural Killer (NK) cells?

They are cytotoxic cells of the innate immune system that kill tumor cells and pathogen-infected cells.

What is the difference between antigen-independent and antigen-dependent lymphopoiesis?

Antigen-independent occurs in primary lymphoid tissue resulting in naive cells; antigen-dependent begins when immunocompetent cells recognize an antigen, driving the adaptive immune response.

What enzyme is responsible for adding random nucleotides during V(D)J gene rearrangement?

Terminal deoxynucleotidyl transferase (TdT)

Which CD marker is expressed through the latest stages of B cell activation?

CD19

What surface immunoglobulin (sIg) markers identify a mature naïve B cell?

IgM and IgD

What are the five types of identical heavy chains found in immunoglobulins?

$\alpha$ (IgA), $\delta$ (IgD), $\epsilon$ (IgE), $\gamma$ (IgG), and $\mu$ (IgM)

Where are B1 lymphocytes primarily located?

Body cavities and mucosal sites

Which MHC Class presents antigen fragments to $CD8+$ T cells?

Class I (HLA-A, HLA-B, HLA-C)

Which MHC Class presents antigen fragments to $CD4+$ T cells?

Class II (HLA-DP, HLA-DQ, HLA-DR)

What percentage of peripheral blood T cells are typically $CD4+$ (helper T cells)?

$$60-80\%$$

Which lymphocyte subtype is characterized by the markers $CD16+$ and $CD56+$?

Natural Killer (NK) cells

What is the size range for a lymphoblast?

$$10-18\,\mu\text{m}$$

Describe the nuclear appearance of a small lymphocyte.

Nucleus occupies about $90\%$ of the cell, chromatin is deeply condensed (stains deep purple), and nucleoli are rarely visible.

What morphology is described as having a 'hand-mirror' shape due to motility?

Small lymphocyte

What are the common morphologic features of a reactive lymphocyte?

Increased size ($16-30\,\mu\text{m}$), decreased N:C ratio, irregular nucleus, increased cytoplasmic basophilia, and cytoplasm that may 'hug' surrounding RBCs.

What specific B-cell daughter cells are the effector cells of humoral immunity?

Plasma cells

Describe the characteristic nucleus of a plasma cell.

Eccentrically placed with coarse blocklike radial masses of chromatin in a 'cartwheel' or 'spoke wheel' arrangement.

What is the 'hof' in a plasma cell?

A clear zone in the cytoplasm representing the Golgi apparatus.

Define lymphocytosis.

An increase in the absolute number of lymphocytes to $> 3.2 \times 10^3/\mu\text{L}$

Define lymphocytopenia.

A decrease in the absolute number of lymphocytes to $< 1.0 \times 10^3/\mu\text{L}$

What percentage of peripheral blood lymphocytes are 'long-lived' memory cells?

$$80\%$$

What is the result of a monoclonal gammopathy?

An increase in one specific class of Ig with identical heavy and light chains.

How does the thymus change during aging?

It atrophies to approximately $15\%$ of its maximum size, leading to a decline in the naive T cell population.

What are the three primary cytokines that regulate neutrophil production?

Interleukin-3 (IL-3), Granulocyte monocyte colony-stimulating factor (GM-CSF), and Granulocyte colony-stimulating factor (G-CSF).

List the six morphologically identifiable stages of neutrophil maturation in order.

Myeloblast, promyelocyte, myelocyte, metamyelocyte, band neutrophil, and segmented neutrophil.

Which neutrophil precursor is the first to show primary (azurophilic) granules containing peroxidase?

Promyelocyte

What is the hallmark feature of the myelocyte stage?

The appearance of secondary (specific) granules and being the last stage capable of mitosis.

Describe the nuclear shape of a metamyelocyte.

Kidney bean shaped

What nuclear morphology characterizes a band neutrophil?

C, U, or S shaped nucleus with coarse, clumped chromatin.

What defines a hypersegmented neutrophil?

A segmented neutrophil with more than 5 lobes.

What are the two neutrophil pools in the bone marrow?

Mitotic pool (proliferating) and Postmitotic pool (maturation and storage).

What are the two neutrophil pools in the peripheral blood?

Circulating pool (CP) and Marginating pool (MP).

How long do neutrophils typically stay in peripheral blood before moving into tissues?

$$\sim 7.5\,\text{hours}$$

What are the four functional steps of a neutrophil at the site of infection?

1. Adherence; 2. Migration (chemotaxis); 3. Phagocytosis; 4. Bacterial killing.

What molecules assist neutrophils in 'rolling' along the endothelium?

Selectins

What is diapedesis?

The process where neutrophils move into tissues by squeezing between endothelial cells.

What are opsonins, such as IgG or C3b, used for?

They 'tag' pathogens to make attachment and phagocytosis easier for neutrophils.

What are Neutrophil Extracellular Traps (NETs)?

Web-like structures made of DNA and antimicrobial proteins that trap microbes outside the cell.

Which cytokine primarily influences eosinophil production?

Interleukin-5 (IL-5) produced by T cells.

What are the functional roles of eosinophils?

Involved in allergy/asthma reactions, parasite defense, and downregulating allergic reactions by inactivating basophil mediators.

What concentration defines eosinophilia?

$$> 0.40 \times 10^3/\mu\text{L}$$

What is the rarest White Blood Cell (WBC) in peripheral blood?

Basophil ($0-1\%$ relative)

What is the primary content of basophil granules?

Histamine and other inflammatory mediators.

What are the three macrophage subtypes based on tissue location?

Kupffer cells (liver), Alveolar macrophages (lungs), Langerhans cells (skin), and Microglial cells (brain).

What is the largest mature cell found in peripheral blood?

Monocyte ($12-20\,\mu\text{m}$)

What define monocytosis clinically?

An absolute monocyte count $> 1.3 \times 10^3/\mu\text{L}$

What is the reference range for T lymphocyte counts in peripheral blood?

$$0.7-3.0 \\times 10^3/\\mu\\text{L}$$

What is the reference range for B lymphocyte counts in peripheral blood?

$0.1-1.0 \\times 10^3/\\mu\\text{L}$ (or $0.1-1.0 \\times 10^9/\\text{L}$)\n\n

What is the reference range for Natural Killer (NK) cell counts in peripheral blood?

$0.0-0.5 \\times 10^3/\\mu\\text{L}$ (or $0.0-0.5 \\times 10^9/\\text{L}$)\n\n

How do reactive lymphocytes differ morphologically from small lymphocytes?

Reactive lymphocytes are larger ($16-30\\,\\mu\\text{m}$), with increased basophilia, decreased N:C ratio, and irregular nuclei.

What is a key morphological feature of plasma cells?

Plasma cells have an eccentrically placed nucleus with a 'cartwheel' appearance of chromatin.

What morphology characterizes a myeloblast in neutrophil maturation?

Myeloblasts have a large nucleus with a fine chromatin pattern and prominent nucleoli.

What morphological aspect distinguishes band neutrophils?

Band neutrophils have a U, C, or S shaped nucleus that is coarse and clumped.

Which diseases are associated with lymphocytosis?

Chronic infections, leukemias, lymphomas, and autoimmune diseases are common conditions linked to lymphocytosis.

What is the significance of monocytosis in disease correlation?

Monocytosis is often seen in chronic inflammation, infections, and hematological malignancies.

Which disease states are commonly linked to eosinophilia?

Eosinophilia is typically associated with allergies, parasitic infections, and certain malignancies.

What diseases correlate with basophilia?

Basophilia can be observed in chronic myeloid leukemia (CML) and other myeloproliferative disorders.

What is the reference range for monocyte counts in peripheral blood?

$0.2-0.8 \\times 10^3/\\mu\\text{L}$ (or $0.2-0.8 \\times 10^9/\\text{L}$)\n\n

What is the normal range for eosinophil counts in peripheral blood?

$0.0-0.4 \\times 10^3/\\mu\\text{L}$ (or $0.0-0.4 \\times 10^9/\\text{L}$)\n\n

What is the normal reference range for basophil counts in peripheral blood?

$0.0-0.1 \\times 10^3/\\mu\\text{L}$ (or $0.0-0.1 \\times 10^9/\\text{L}$)\n\n

What morphology characterizes eosinophils?

Eosinophils typically have a bi-lobed nucleus and large orange-red granules in their cytoplasm.

What feature distinguishes basophils from other white blood cells?

Basophils have large blue-purple granules that obscure the nucleus, containing histamine and heparin.

What defines neutrophilia in clinical terms?

An absolute neutrophil count greater than $7.0 \\times 10^3/\\mu\\text{L}$ is defined as neutrophilia.

What are the characteristics of chronic myeloid leukemia (CML) in relation to white blood cell counts?

CML is associated with elevated total white blood cell counts, often with marked neutrophilia and basophilia.

What are the characteristic changes in morphology for lymphopenia?

Lymphopenia is characterized by a decreased number of lymphocytes, often with a predominance of other white blood cell types.

What is the function of macrophages in the immune response?

Macrophages phagocytize pathogens and dead cells and serve as antigen-presenting cells to T lymphocytes.

Describe the role of dendritic cells in immunity.

Dendritic cells capture and present antigens, activating T cells and linking the innate and adaptive immune responses.