WBC Disorders (210 Hematology) – Flashcards
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Hematopoiesis
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Blood cells are formed in bone marrow, where they mature Stem cells give rise to all blood cells, including RBCs, WBCs & platelets Progenitor cells differentiate Precursor cells acquire morphologic features of each cell type Cells enter bloodstream
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Normal Peripheral White Blood Count
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4,800-10,800 cells/µL (adult) Slightly lower in blacks Slightly higher during pregnancy Much higher in infants & young children
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WBC Types (Peripheral Blood)
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Segmented Neutrophils Band Neutrophils Lymphocytes Monocytes Eosinophils Basophils
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Lymphocytes
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13-46% of WBCs Small, dark blue Scant cytoplasm INCREASE in acute viral illness such as EBV, CMV Reactive lymphocytes (normal response to infection) -Plasma cells: thought to be progeny of B lymphocytes, not in peripheral blood, live in tissues -Stimulated in infection
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T Cells
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Cytotoxic T cells -bind to antigens on plasma membrane of target cells (cancer, virus-infected, foreign tissue) & directly destroy cells Helper T cells -secrete cytokines, activating B cells, cytotoxic T cells, NK cells & macrophages NK cells -bind directly & nonspecifically to virus infected & cancer cells to kill them, function as killer cells in Ab-dependent cellular toxicity
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B Cells
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Initiate Ab-mediated immune responses by binding specific antigens to B cell plasma membrane receptors (immunoglobulins) Transform into plasma cells after activation Present antigen to helper T cells
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Monocytes
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3-9% of WBCs Largest WBC, irregular shape, light blue cytoplasm May be increased in some chronic bacterial infections (TB), or during recovery from acute infections Phagocytic Extracellular killing via secretion of toxic chemicals Process & present antigen to helper T cells Secrete cytokines involved in inflammation, activation & differentiation of helper T cells, & systemic responses to infection or injury (the acute phase response) Enter tissue & transform into macrophages Macrophages perform same functions in TISSUES
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Neuitrophils
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Granulocytes 53-79% of WBCs Granules stain neutral Light pink cytoplasm Phagocytize debris & bacteria, kill microbes Pathognomonic of acute inflammation Release chemicals involved in inflammation (vasodilators, chemotaxins, etc.)
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Bands
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Immature neutrophils 0-10% of WBCs Nucleus shape not segmented INCREASE in peripheral blood is called "left shift"
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Eosinophils
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Granulocytes 0-4% of WBCs Granules stain reddish-orange Modulate immunologically mediated inflammation Participate in immediate hypersensitivity reactions Destroy multicellular parasites
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Basophils
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Granulocytes 0-1% of WBCs Granules stain deep blue/purple ?? Function in CIRCULATION INCREASE in CML, UC Related to mast cells in chemical characteristics & function (mast cells do not circulate, are found in most connective tissues & organs) Acute & delayed allergic reactions Mast cells release histamine & other inflammatory substances
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Diagnostic Methods for WBCs (Tests)
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CBC (complete blood count) WBC differential Bone marrow evaluation Lymph node biopsy Protein electrophoresis (PEP): Serum (SPEP) Urine (UPEP) Special stains
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2 Parts of WBC COUNT
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Total number of WBCs -Per 1mm^3 (µl) peripheral blood Differential count -% each type of leukocyte in same specimen
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MANUAL Differential
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Stain whole blood film Microscopic exam Scan film with low magnification Estimate WBC count & platelet count
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Left Shift
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increased prominence of immature WBCs in differential, usually from acute bacterial infection
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Leukopenia
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decrease in total WBC count; seen in viral infections, radiation, drugs, or chemical exposure
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Leukocytosis
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increase in total WBC count; seen in infectious disease (esp. bacterial) or leukemia
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Leukemoid Reaction
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EXTREME increase in WBC count (to levels seen in leukemia, but caused by infection, esp. sepsis); RESOLVES with treatment
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Lymphocytosis
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lymphocyte value is higher than reference range
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Eosinophilia
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high eosinophils
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Absolute Neutrophil Count (ANC)
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One measure of risk for infection ANC = WBC x (% Neutrophils + % Bands) Immunocompromised if ANC < 1000
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5 Abnormal WBC Inclusions (Morphology)
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Auer rods Döhlebodies Toxic granulation Neutrophil hypersegmentation Vacuoles
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Auer Rod
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Red/pink narrow rod in cytoplasm Found in blasts Suggests AML
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Dohle Body
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Blue irregular patch or patches Near edge of neutrophil Associated with infection
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Toxic Granulation
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Prominent purple/blue-black granules Seen in neutrophils Severe systemic infection & toxic states
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Hypersegmentation
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6 or more lobes or >3% with 5+ lobes In neutrophils Megaloblasticanemia, B12-folate deficiency, myeloproliferative d/o
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Vacuoles
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Degenerative changes In monocytes & neutrophils May suggest sepsis
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Bone Marrow Aspiration/Biopsy
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Bone marrow aspiration -Dry tap may require repositioning needle or biopsy procedure -Iliac Crest Bone marrow biopsy If marrow is hypoplastic or hyperplastic (& unable to aspirate)
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Special Stains
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Used to identify & diagnose specific conditions Many available Ex: leukocyte alkaline phosphatase (LAP) -Low in CML -High in leukemoid reactions
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Myelodysplastic Syndromes
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Cytopenia with a hypercellular bone marrow Morphologic abnormalities in two or more hematopoietic cell lines Cytogenetic abnormalities Despite adequate numbers of progenitor cells, ineffective hematopoiesis occurs Sometimes termed "preleukemia"
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Immunoproliferative Diseases
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Multiple Myeloma (more common) Monoclonal Gammopathy of Uncertain Significance (MGUS) Waldenström's macroglobinemia
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Multiple Myeloma
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Excess plasma cell clone production Collection in bone marrow = myeloma Multiple collections = multiple myeloma, seen as multiple bone lesions Findings: anemia, hypercalcemia, marked monoclonal spike in IgG ;/or IgA on SPEP, monoclonal proteins on UPEP (Bence-Jones proteins), lytic lesions on skeletal radiograph
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4 Types of Leukemias
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ALL: acute lymphoblastic leukemia AML: acute myelogenousleukemia CLL: chronic lymphocytic leukemia CML: chronic myelogenousleukemia
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Leukemia
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Definitive diagnosis of leukemia: blasts on bone marrow; most often presents as blasts in peripheral blood Findings: -INCREASE WBC on CBC -DECREASE PLT (acute), NL (chronic) -Hct/Hgb: normocytic normochromic anemia CLLs ; CMLs characterized by gradually increasing #s of mature cells in marrow
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Leukemia Evaluation
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Morphology of WBCs Cytochemistry (special stains) Genetic analysis (chromosomal, molecular) Immunology / Serology
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Acute Leukemias
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Rapid onset with symptoms common Pancytopenia with circulating blasts Bone marrow hypercellular ; dominated by blasts
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Chronic Leukemias
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Slow onset, many patients asymptomatic Disorders of middle age
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2 Major Lymphomas
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Hodgkin lymphoma (HL) Non-Hodgkin lymphomas (NHL) -Classification controversial, recently based on both clinical ; pathologic features
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Hodgkin Lymphoma
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Arises from lymph tissue Pathologic diagnosis by lymph node biopsy Reed-Sternberg cells present in peripheral blood
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Non-Hodgkin Lymphoma
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Peripheral blood may be normal, some have leukemic phase INCREASED serum LDH Lymph node biopsy required for diagnosis ; staging
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Infectious Diseases with WBC Findings
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Infectious Mononucleosis Ehrlichiosis Histoplasmosis Cryptococcus Neoformans HIV (covered in Infectious Disease unit of ClinMed)
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Infectious Mononucleosis
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Cause: Epstein-Barr virus (EBV) Findings: Lymphocyte pleomorphismon blood film with lymphocytosis ; 10% reactive lymphocytes! INCREASED EBV titer Heterophile Ab Bone marrow = normal
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Ehrlichiosis
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Cause: tick-borne Ehrlichiaebacteria Findings: Clustered bacteria in vacuoles in neutrophils, or monocytes ; macrophages on blood film (depends on type of Ehrlichia) Thrombocytopenia Leukopenia with left shift in neutrophils Rising Ab immunofluorescence titer
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Histoplasmosis
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Cause: intracellular fungus Histoplasma capsulatum Findings: Usually in immunocompromised patients Organism in neutrophils ; monocytes on Wright-Giemsa stained blood film Organism in macrophages on bone marrow smear
