Hematology - Leukocytes
C. Risk of infection C. Neutropenia is associated with a risk of infection. The degree of neutropenia correlates with the infection risk from high susceptibility (<1.0 X 109/L) to great risk (<0.5 X 109/L). Infection increases with the degree and duration of the neutropenia. Shortness of breath and bleeding tendencies are clinical symptoms associated with severe anemia and thrombocytopenia, respectively.
Of the following, an absolute neutrophil count of 1.0 X 109/L would be associated with A. Shortness of breath B. Bleeding tendencies C. Risk of infection D. No clinical symptoms
B. An increase in immature blood cells following release of bone marrow pools B. A "shift to the left" means an increase in immature neutrophilic cells in the blood caused by bone marrow release of cells in response to infection or tissue damage. A redistribution of the blood pools because of emotional or physical stimuli is characterized by an increased WBC count without a left shift. A cell "hiatus" refers to a population of cells in which there is a gap in the normal maturation sequence. A cell hiatus is most often seen in acute leukemia, in which there are many blasts and a few mature cells but no intermediate stages.
A "shift to the left," when used to describe a cell population, refers to A. Increased cells in the blood due to a redistribution of blood pools B. An increase in immature blood cells following release of bone marrow pools C. A cell production "hiatus" or gap D. A higher percentage of lymphocytes than neutrophils
C. There is a relative lymphocytosis. C. Absolute values for cell types are obtained by multiplying the percentage of the cell type by the total number of cells. In this case, 4000/mm3 X 0.65 = 2600/jJiL or 2.6 X 109/L. Although reference ranges vary, the normal absolute count for lymphocytes is from 1.0 to 4.0 X 109/L and the normal percentage of lymphocytes is 20-44%. In this case, there is a relative lymphocytosis (increase in percentage), but the absolute lymphocyte value is normal. Percentages can be misleading, so the absolute number of a particular cell type should always be evaluated.
An adult has a total white blood cell count of 4.0 X 109/L (4.0 X 103/uL). The differential count is as follows: polymorphonuclear neutrophils (PMNs) 25%, bands 5%, lymphocytes 65%, and monocytes 5%. The absolute value reference range for lymphocytes is 1.0—4.0 X 109/L. Which of the following is true? A. The percentage of lymphocytes is normal. B. There is an absolute lymphocytosis. C. There is a relative lymphocytosis. D. There is both an absolute and a relative lymphocytosis.
C. Phagocytes, immunocytes C. The major function of leukocytes is defense, either by phagocytosis or by immune mechanisms. The phagocytic cells are the granulocytes and monocytes. The immune response is mediated by lymphocytes; however, monocytes play a role in immunity as antigen-presenting cells. Leukocytes may be classified according to granularity as granulocytes and nongranulocytes or divided based on nuclear segmentation as polymorphonuclears (PMNs) and mononuclears
Functionally, white blood cells are divided into A. Granulocytes, nongranulocytes B. Polymorphonuclears, mononuclears C. Phagocytes, immunocytes D. Granulocytes, lymphocytes
C. Myelocyte C. The precursor cell that can first be recognized as granulocytic is the myeloblast and has no granules. Primary or nonspecific granule production begins and ends during the promyelocyte stage. The granules are distributed between daughter cells as mitotic divisions occur. Secondary or specific granule production begins with the myelocyte stage and continues during succeeding cell stages with the synthesis of products specific to the function of the particular granulocyte (neutrophil, eosinophil, or basophil)
Production of primary granules ceases and production of secondary granules commences with what cell stage? A. Myeloblast B. Promyelocyte C. Myelocyte D. Metamyelocyte
C. Myelocyte C. The last stage in the granulocytic series that divides is the myelocyte. Cells before and including this stage constitute the bone marrow mitotic pool and undergo multiple cellular divisions. Nuclear chromatin progressively clumps and nucleoli are no longer present in the nondividing metamyelocyte stage that follows the myelocyte.
The most mature granulocyte precursor that can undergo mitosis is the A. Myeloblast B. Promyelocyte C. Myelocyte D. Metamyelocyte
A. Myeloblasts and promyelocytes A. The granulocyte mitotic pool contains the cells capable of division, which are the myeloblasts, promyelocytes, and myelocytes. The post-mitotic pool, or reserve, is the largest bone marrow pool and contains metamyelocytes, band and segmented forms. This pool is available for prompt release into the blood if needed (e.g., infection), and its early release is the cause of a "left shift." If released, the bone marrow mitotic pool can dramatically increase its activity to replenish this reserve (cytokine stimulation increases).
What does the granulocyte mitotic pool in the bone marrow contain? A. Myeloblasts and promyelocytes B. Band and segmented forms C. The majority of marrow granulocytes D. Myelocytes and metamyelocytes
A. Less than 1 day A. After granulocytes are released from the bone marrow, they remain in the circulation one day or less. Their major function takes place in the tissues. They migrate through the vessel walls to reach areas of inflammation very soon after release. The life span of the granulocyte is short; however, eosinophils and basophils appear to survive longer in the tissues than neutrophils.
What is the approximate amount of time a granulocyte spends in the circulation before migrating into the tissues? A. Less than 1 day B. About 3 days C. Up to 5 days D. More than 10 days
B. Colony stimulating factor B. The growth factor mainly responsible for regulating the production of granulocytes and monocytes is granulocyte/monocyte colony stimulating factor (GM-CSF), which acts on the committed bipotential progenitor cell CFU-GM (colonyforming unit GM). GM-CSF stimulation of granulocyte or monocyte production increases in response to need and can also affect the production of erythrocytic and megakaryocytic lineages. G CSF induces granulocyte differentiation, and M-CSF supports monocyte differentiation. Erythropoietin (EPO) is a lineage-specific growth factor responsible for stimulating erythrocyte production, and thrombopoietin (TPO) is mainly responsible for regulating platelet production. Interleukins, particularly IL-3, influence multiple cell lines, including granulocytes and monocytes.
What is the growth factor that is primarily responsible for regulating granulocyte and monocyte production? A. Erythropoietin B. Colony stimulating factor C. Interleukin D. Thrombopoietin
D. Monocyte D. Monocytes have a diameter up to 20 making them the largest cells in the peripheral blood under normal conditions. Eosinophils and neutrophils have diameters of about 12 |xm. The small lymphocyte is 8-9 |xm in diameter, similar to the red blood cell, which has a diameter of 6-8 (xm. Large lymphocytes range in size from 11 to 16 jim in diameter.
What is the largest white blood cell normally found in the peripheral blood? A. Eosinophil B. Neutrophil C. Lymphocyte D. Monocyte
A. Neutrophil A. Although some phagocytic activity has been attributed to the eosinophil, it is the segmented neutrophil and monocyte that have the greatest phagocytic activity. The neutrophil is the most important because of numbers and its ability to respond quickly, especially against bacterial pathogens. Monocytes arrive at the site of injury after the neutrophil to "clean up."
What is the major phagocytic cell involved in the initial defense against bacterial pathogens? A. Neutrophil B. Eosinophil C. Basophil D. Monocyte
A. Diapedesis A. Diapedesis is the movement of cells (usually referring to neutrophils) from the blood stream into the tissues by squeezing through endothelial cells of the vessel wall. Chemotaxis is the movement of cells directed by chemotactic stimuli such as bacterial products, complement components, or injured tissue. Opsonization is the coating of an organism or foreign particle by IgG or complement for recognition and phagocytosis by neutrophils or monocytes. The ingestion of red cells, often coated with IgG or complement, is called erythrophagocytosis. Margination is the attachment of neutrophils to the endothelial lining of the blood vessels.
What is the term for cell movement through blood vessels to a tissue site? A. Diapedesis B. Opsonization C. Margination D. Chemotaxis
C. 50% C. Approximately 50% of the neutrophils in the peripheral blood are found in the circulating pool. This is the pool measured when a total WBC count is done. Another 50% are found adhering to vessel walls (marginal pool). These pools are in constant exchange. Emotional or physical stimuli can cause a shift of cells from the marginating pool to the circulating pool, causing a transient rise in the total WBC count. The total WBC count can double but returns to normal within several hours
What percentage of neutrophils in the peripheral blood constitutes the circulating pool? A. 100% B. 80% C. 50% D. 30%
A. Toxic granules and Dohle bodies in the neutrophils A. The presence of toxic granules, Dohle bodies, and/or vacuoles in the cytoplasm of neutrophils (segmented, band, metamyelocyte, and myelocyte stages) is indicative of a neutrophilic response to inflammation. The changes observed in the "toxic" neutrophil may occur in patients with severe burns, some malignancies, exposure to toxic drugs and chemicals, and acute infection (most often bacterial). A Barr body is a "drumstick"-shaped body of nuclear material found in the neutrophils of females that represents the inactive X chromosome and is of no significance. Auer rods are seen in malignant myeloid cells, usually blasts. Hypersegmented neutrophils are associated with megaloblastic anemias but may be seen in long-term chronic infections. Pyknotic cells and vacuoles may be seen in overwhelming sepsis or in a degenerating blood specimen. Russell bodies are globular inclusions found in plasma cells that are composed of immunoglobulin.
Which of the following are indicators of a neutrophilic response to tissue damage or inflammatory stimuli? A. Toxic granules and Dohle bodies in the neutrophils B. Vacuoles and Barr bodies in the neutrophils C. Hypersegmented neutrophils and Auer rods D. Pyknotic neutrophils and Russell bodies
D. Sex D. The total white blood cell count reference ranges for males and females are equivalent. WBC counts do change with age, being higher in newborns and children than in adults. Any change from basal conditions, such as exercise or emotional stress, will cause a transient leukocytosis due to a redistribution of blood pools. WBC values are lower in the morning and higher in the afternoon (diurnal variation).
Which of the following factors is not associated with variations in the total white blood cell count? A. Age B. Exercise C. Emotional stress D. Sex
D. Decreased numbers of granulocytes D. "Agranulocytosis" refers to an absence of granulocytes in both the peripheral blood and bone maiTow. A deficiency of granulocytes is found in cases of aplastic anemia, in which deficiencies in red cells and platelets also occur. The early release of cells from the bone marrow will result in immature cells in the blood but is not referred to as agranulocytosis. Neutrophils that exhibit little or no granulation may be called hypogranular or agranular and are a sign of abnormal growth (dyspoiesis).
Which of the following is characteristic of agranulocytosis? A. Neutrophils without granules B. Decreased numbers of granulocytes, red cells, and platelets C. Immature granulocytes in the peripheral blood D. Decreased numbers of granulocytes
A. Coated with a phospholipid membrane A. Primary granules, which appear in the promyelocyte stage, may be called azurophilic or nonspecific granules. Specific or secondary granules (neutrophilic, eosinophilic, basophilic) appear in the myelocyte stage. Primary granules contain hydrolytic enzymes (e.g., myeloperoxidase, lysozyme, acid phosphatase) and are coated with a phospholipid membrane. Lactoferrin is a component of neutrophil granules. Primary granules are visible in the myelocyte stage, but in later stage cells the primary granules, although present, are less visible by light microscopy under normal conditions.
Which of the following is characteristic of primary granules? A. Coated with a phospholipid membrane B. Called azurophilic or specific granules C. Contain myeloperoxidase and lactoferrin D. Present in the promyelocyte stage only
B. Synthesize antibody B. Antibodies are synthesized by plasma cells, which are end-stage B lymphocytes that have transformed to plasma cells following stimulation by antigen. An end product of T cell activation is the production of cytokines (lymphokines) such as interleukins and colony-stimulating factors. T cells are surveillance cells that normally comprise the majority (about 80%) of lymphocytes in the blood. T cells regulate the immune response by helping (T helper or inducer cells) or suppressing (T suppressor cells) the synthesis of antibody by plasma cells.
Which of the following is not a characteristic of T lymphocytes? A. Secrete cytokines B. Synthesize antibody C. Comprise majority of cells in the blood lymphocyte pool D. Regulate the immune response
B. Membrane receptors bind IgG, initiating anaphylactic reactions. B. Basophils and tissue mast cells have receptors for IgE and complement components, which trigger degranulation when appropriate antigens are present and are responsible for severe hypersensitivity reactions (anaphylaxis). Basophils and tissue mast cells have morphologic similarities but represent distinct cell types. Basophils possess water-soluble granules that contain, among other substances, heparin and histamine (a vasodilator and smooth muscle contractor). Basophils have a segmented nucleus, and the granules, although often scanty, overlie the nucleus. The mast cell has a single round nucleus, contains many more granules than the basophil, and can be found in the bone marrow.
Which of the following statements about basophils is false? A. Morphologically, basophils resemble tissue mast cells. B. Membrane receptors bind IgG, initiating anaphylactic reactions. C. Basophilic granules contain heparin and histamine. D. Granules are water soluble.
B. Eosinophilic granules contain lysozyme B. Eosinophils lack lysozyme, which is present in neutrophils and monocytes, and contain a distinctive peroxidase that differs biochemically from the myeloperoxidase of neutrophils and monocytes. Major basic protein is a component of the granules and is very important to the ability of eosinophils to control parasites. In addition, eosinophils play a role in modifying the allergic reactions caused by degranulation of basophils. Basophils release eosinophil chemotactic factor of anaphylaxis (ECF-A), which calls eosinophils to the site.
Which of the following statements about eosinophils is false? A. They contain a type of peroxidase that is distinct from that of neutrophils. B. Eosinophilic granules contain lysozyme C. Eosinophils are an important line of defense against parasites. D. Major basic protein is a component of eosinophil granules.
B. Auer rods are composed of fused primary granules. B. Auer rods are seen in the cytoplasm of malignant cells, most often myeloblasts, and are composed of fused primary (nonspecific, azurophilic) granules. Hypersegmented neutrophils have five lobes or more and are associated with vitamin B12 or folate deficiency. Toxic granules are primary granules with altered staining characteristics that stain in late-stage neutrophils due to toxicity. Dohle bodies are agranular patches of RNA present in neutrophil cytoplasm and associated with toxic states.
Which of the following statements is correct? A. Hypersegmented neutrophils have four nuclear lobes. B. Auer rods are composed of fused primary granules. C. Toxic granules are prominent secondary granules. D. Dohle bodies are agranular patches of DNA.
