Hematology - Leukocytes Pt 2
D. Basophils D. Basophil granules contain histamine, a potent vasodilator and smooth muscle contractor, that is responsible for the systemic effects seen in immediate hypersensitivity reactions (type I), which are also termed anaphylaxis. Degranulation occurs when basophils are coated with an IgE type of antibody that recognizes a specific allergen, such as bee venom, certain plant pollens, or latex. The resulting anaphylactic shock can be life threatening.
Vasodilation and bronchoconstriction are the result of degranulation by which of the following blood cells? A. Eosinophils B. Monocytes C. Neutrophils D. Basophils
B. Spleen and lymph nodes B. Antigen-independent lymphopoiesis occurs in primary lymphoid tissue located in the thymus and bone marrow. The formation of immunocompetent T and B cells from the lymphoid progenitor cell is influenced by environment (thymus, marrow) and several interleukins. Antigen-dependent lymphopoiesis occurs in secondary lymphoid tissue (spleen, lymph nodes, Peyer's patches) and begins with antigenic stimulation of immunocompetent T and B cells. Lymphocytes are the only white cells that recirculate (i.e., return to the blood from the tissues).
Antigen-dependent lymphopoiesis occurs in secondary lymphoid tissue located in the A. Liver and kidney B. Spleen and lymph nodes C. Lungs and Peyer's patches D. Thymus and bone marrow
B. Plasma cells B. Plasma cells are the mature end stage of the B lymphocyte, producing immunoglobulins (antibodies) in response to activation by a specific antigen (humoral immunity). The antibody produced by a single plasma cell is of one immunoglobulin type. Natural killer (NK) cells recognize and kill tumor cells or cells infected with virus through direct contact. Virocytes are reactive lymphocytes, and thymocytes are immature T cells. T lymphocytes provide cellular (cell mediated) immunity.
Cells that produce immunoglobulins in response to antigenic stimulation are designated A. Natural killer cells B. Plasma cells C. Virocytes D. Thymocytes
B. Monoclonal antibody reactions to surface and cytoplasmic antigens B. Morphologic criteria such as cell size, nuclear shape, and chromatin pattern or cytoplasmic granularity cannot be used to identify lymphocyte subtypes. Monoclonal antibodies (CD surface markers) to specific surface and cytoplasmic antigens can distinguish lymphocyte subpopulations and identify the development stage. For example, blood lymphocytes that are B cells express CD 19 and CD20 markers, T cells express CD2 and CDS (and either CD4 or CDS markers), and NK cells express CD56. Natural killer cells often exhibit large granular lymphocyte morphology (LGLs).
On what basis can B and T lymphocytes be distinguished? A. Differences in nuclear shape B. Monoclonal antibody reactions to surface and cytoplasmic antigens C. Cytoplasmic granularity and overall cell size D. Chromatin pattern in the nucleus
A. 1 to 4 years A. Young children have the highest peripheral lymphocyte concentrations, ranging from 4.0 to 10.5 X 109 cells/L at 1 year of age and declining to 2.0-8.0 X 109 cells/L by 4 years of age. Lymphocyte counts decrease with age because of a decrease in lymphocyte stimulation and processing of antigens, ranging from 1.0 to 4.0 X 109 cells/L in adults. In addition to the difference in lymphocyte number in children, the normal morphology of children's lymphocytes differs from that of adults. Patient age should be considered when deciding between normal and abnormal lymphocytes.
Lymphocyte concentrations in the peripheral blood are greatest during what age interval? A. 1 to 4 years B. 4 to 15 years C. 16 to 40 years D. 40 to 70 years
B. Indentation of nucleus B. Indentation of the nucleus (kidney shape) is the feature that characterizes the metamyelocyte stage. Specific granules begin forming in the myelocyte and persist through later stages. Cytoplasmic color is not a reliable feature, because it is variable and may not differ significantly from the myelocyte or band stage. Nucleoli are absent in metamyelocytes and may not be visible in myelocytes (they may be indistinct).
Which of the following can differentiate metamyelocytes from other stages of granulocyte maturation? A. Presence of specific granules B. Indentation of nucleus C. Absence of nucleoli D. Color of cytoplasm
C. Irregular, indented nuclear shape C. The nucleus in both monocytes and reactive lymphocytes can be irregular in shape, with indentations, although a monocyte nucleus often has folds and lobulations. Reactive lymphocytes characteristically have an increased amount of dark blue cytoplasm, whereas monocyte cytoplasm is usually a blue-gray color. Lymphocytes lack the many fine granules that give monocytes a typical "ground glass" appearance of the cytoplasm, but monocytes can occasionally have larger granules. Sharp indentation of the cytoplasm by adjacent red cells and an increased number of large granules are features of reactive lymphocytes. Vacuoles, although more commonly present in monocytes, can also be seen in reactive lymphocytes.
Which of the following characteristics would be least likely to distinguish reactive lymphocytes from monocytes? A. Sharp indentation of the cytoplasmic margin by adjacent red blood cells B. Presence of large azurophilic granules C. Irregular, indented nuclear shape D. Abundant, deeply basophilic cytoplasm
D. Myeloperoxidase D. Myeloperoxidase is an enzyme present in the primary granules, regardless of the phagocytic activity of the cell. The products produced during the respiratory burst, many of them short lived, are generated in response to chemotactic activation and ingestion of microbes. Generation of oxygen metabolites is necessary for microbial killing.
Which of the following is not produced by neutrophils during the respiratory burst? A. Hydroxyl radicals (OH~) B. Hydrogen peroxide (H2O2) C. Superoxide anion (O^~) D. Myeloperoxidase
A. SIgM, a surface membrane immunoglobulin A. Early B cell precursors would be expected to express TdT, CD 10, and CD34. TdT, the enzyme marker for terminal deoxynucleotidyl transferase, and the stem cell marker CD34 are present on the earliest B or T lymphoid cells. Surface immunoglobulin (SIgM) can only be detected on B cells at later stages of development. TdT can be used to differentiate the leukemic cells of acute lymphoid leukemia from acute myeloid leukemia. CALLA (CD 10 or common ALL antigen) is a marker found in precursor types of B cell ALL.
Which of the following is the least likely to be expressed by early B cell precursors? A. SIgM, a surface membrane immunoglobulin B. CD34, a hematopoietic stem cell marker C. TdT (terminal deoxynucleotidyl transferase), a nuclear enzyme D. CDlO(CALLA), a surface antigen
C. Their quantity of lysosomes and acid hydrolases decreases during maturation. C. Acid hydrolases and the number of lysosomes increase as the blood monocyte matures into a tissue macrophage. Macrophages are widely dispersed in body tissues and organs of the reticuloendothelial (RE) system (also known as the mononuclear phagocyte system). Macrophages have receptors for IgG and complement,and they serve as phagocytes by ingesting debris and dead cells (usually neutrophils) at sites of inflammation. Macrophages act in the immune response as antigen-presenting cells by ingesting and exposing antigens for recognition by lymphocytes. Monocytes/macrophages secrete complement components and cytokines, including colony stimulating factors and interleukins.
Which of the following statements about macrophages is incorrect? A. They are mature tissue forms of blood monocytes. B. They serve as antigen-presenting cells to the immune system. C. Their quantity of lysosomes and acid hydrolases decreases during maturation. D. They remove damaged or dying cells and cellular debris.
A. Suppress allergic reactions caused by basophils A. A function of the eosinophil is to modify the severe allergic reactions caused by degranulation of the basophil. Neutrophils have receptors for the opsonins IgG and complement and are the most important cell in the initial defense against acute bacterial infection. Neutrophils are nonspecific phagocytes, ingesting bacteria, fungi, dead cells, etc., and they contain hydrolytic enzymes, including muramidase (lysozyme) and alkaline phosphatase. Neutrophils die in the performance of their function and are removed by macrophages.
Which of the following statements about neutrophils is false? A. Suppress allergic reactions caused by basophils B. Have surface receptors for IgG and complement components C. Contain alkaline phosphatase and muramidase D. Act in nonspecific phagocytosis and are destined to die
