Hematology
Name two types of mononuclear cells.
Lymphocytes and monocytes
What cancer results from plasma cells?
Multiple myeloma
You note that a pt's bone marrow shows a monoclonal proliferation of plasma cells. What is the diagnosis?
Multiple myeloma
Which type of leukocyte mediates acute inflammatory responses?
Neutrophil
A healthy man has no need for leukotriene output. If you isolate his basophils and study the intracellular contents, are leukotrienes found?
No—leukotrienes are both synthesized and released on demand by basophils, and therefore none will be found if they are not needed
What skin finding is typically noted in thrombocytopenic patients?
Petechiae
What are the function of macrophages?
Phagocytoses bacteria, cellular debris, and senescent RBCs
What are the characteristic features of plasma cells?
Plasma cells have eccentric nuclei with "clock-face" chromatin, abundant RER, and well-developed Golgi apparatus
During weeks 10-28 of embryogenesis, where does erythropoiesis occur?
Spleen
What role do macrophages play in the immunologic response to extracellular pathogens?
They function as antigen-presenting cells by way of major histocompatibility complex class II molecules
A 78-year-old woman has depression, weakness, and leg paresthesias. Blood smear shows hypersegmented neutrophils. A possible diagnosis?
Vitamin B12 deficiency (folate deficiency can cause similar blood smear findings, but only B12 causes neurologic symptoms)
What are the contents of the α-granules of platelets?
Von Willebrand factor, fibrinogen, fibronectin
Reticulocytes contain RNA. What stain would you use to evaluate RNA, and what color would it appear?
Wright-Giemsa stain; blue
About what percentage of platelets does the spleen store?
0.33
How many leukocytes are normally found per cubic milliliter (cells/mm3) of blood?
4000 to 10,000 cells/mm3
A 65-year-old woman with CML has her blood drawn. What do you expect to see on the complete blood count report?
A high number of band cells (immature neutrophils), reflecting increased myeloid proliferation
A man is in a car accident and requires a blood transfusion. His blood type is AB+. Which blood groups can the patient receive safely?
All blood types (A+, B+, AB+, O)
A man has a bacterial infection. Leukocyte counts are high. You send serum for studies of chemotactic agents. Which ones will be high?
All neutrophil chemotactic agents, which include C5a, IL-8, LTB4, kallikrein, and platelet-activating factor
Which circulating antibodies can be found in the plasma of a patient with the B+ blood type?
Anti-A IgM
Which circulating antibodies can be found in the plasma of a patient with an O blood type?
Anti-A IgM and anti-B IgM
Which circulating antibodies can be found in the plasma of a patient with the A+ blood type?
Anti-B IgM
What stimulus causes degranulation of mast cells?
Antigen binding to IgE-Fc receptor complexes on the surfaces of mast cells
Eosinophils are phagocytic cells, particularly in the presence of what?
Antigen-antibody complexes
A woman taking aspirin is undergoing surgery. How long before surgery must she discontinue aspirin?
At least 8-10 days before surgery (this is the lifespan of a platelet)
What is the response of a B cell after encountering an antigen?
B cells differentiate into plasma cells (secrete antibodies) and memory cells
What are the three types of lymphocytes?
B cells, T cells (B and T cells mediate adaptive immunity), and NK cells (part of the innate immune response)
You are rounding with your team. The attending says to you, "Your patient has a bunch of bands in his blood." What does that mean?
Bands are immature neutrophils, usually seen during states of increased myeloid proliferation such as bacterial infection or CML
From week 18 of embryogenesis until adulthood, where does erythropoiesis occur?
Bone marrow
Name some neutrophilic chemotactic agents.
C5a, LTB4, IL-8, platelet-activating factor, kallikrein
What costimulatory molecule present on B cells is required to activate T cells?
CD28
What is the primary cellular target of HIV?
CD4+ helper T cells
T lymphocytes mediate which type of immune response?
Cellular
What exchange transporter helps RBCs carry CO2?
Cl/HCO3− antiporter on the membrane
What medication could prevent exacerbation of asthma (by preventing the release of inflammatory compounds from mast cells)?
Cromolyn sodium, which stabilizes mast cell membranes and prevents degranulation
Name the three types of mature cells into which T cells differentiate.
Cytotoxic T cells, helper T cells, and regulatory T cells
What is the function of eosinophils?
Defends against helminthic infections (major basic protein)
What is the function of dendritic cell?
Dendritic cells are phagocytes and antigen-presenting cells
What two types of granules do platelets contain?
Dense granules and alpha granules
How does fetal hemoglobin extract oxygen from maternal hemoglobin?
Fetal Hb has higher affinity for oxygen, allowing it to extract oxygen from maternal Hb across the placenta
On what molecule do erythrocytes depend exclusively for energy?
Glucose
In the formation of a stable thrombus, fibrinogen binds platelets together via what receptor?
Glycoprotein IIb/IIIa
In primary hemostasis, von Willebrand factor must be released and bind to what platelet receptor?
Glycoprotein Ib
In a test, you separate all granulocytes from all mononuclear cells. Which of the two groups will likely have a higher number of cells?
Granulocytes, making up 55-65.75% of all leukocytes (mononuclear cells are the remaining 34.25-45%)
Patients taking clozapine require weekly blood draws to screen for agranulocytosis. What cell types are most affected?
Granulocytes—namely, neutrophils, eosinophils, and basophils
A doctor mistakenly administers AB+ blood to a patient with B+ blood. What reaction will be seen? Why?
Hemolytic reaction; the patient has anti-A IgM antibodies in plasma
What molecules are released during basophil degranulation? What stain is best for identifying basophils?
Heparin (anticoagulant), histamine (causes vasodilation), and leukotrienes are released; basophils stain best with basic stains
A blood smear from a patient with severe anemia contains immature RBC forms. What does this mean?
Immature RBCs, or reticulocytes, reflect erythroid proliferation (an attempt by the patient's bone marrow to replenish the lost RBCs)
What are dendritic cells in the skin called?
Langerhans cells
What do specific granules in neutrophils contain?
Leukocyte alkaline phosphatase, lactoferrin, lysozyme, collagenase
Granulocytes and mononuclear cells are what kind of blood cells?
Leukocytes (leuk = white and cyte = cell)
From week 6 of embryogenesis until birth, where does erythropoiesis occur?
Liver
What structure contains proteinases, acid phosphatase, myeloperoxidase, and B-glucuronidase?
Lysosomes (azurophilic granules)
Which major histocompatibility complex and CD molecules are expressed by cytotoxic T cells?
MHC I and CD8 (MHC 1 × CD8 = 8
Which MHC and CD molecules are expressed by helper T cells?
MHC II and CD4 (MHC 2 × CD 4 = 8)
What major histocompatibility complex do B cells possess on the cell surface?
MHC II, which allows B cells to act as antigen-presenting cells
A boy has anal pruritus because of a helminth infection. Which granulocyte enzyme is important in the body's defense against this parasite?
Major basic protein (a helminthotoxin), which is secreted by eosinophils
What cells differentiate into macrophages in tissue?
Mono = one (nucleus); cyte = cell
A patient with TB has numerous granulomas on bronchoscopy. The leukocyte important to their formation was activated from which precursor?
Monocytes differentiate into macrophages within the tissues—macrophages are important in granuloma formation
Describe the identifying features of a monocyte.
Monocytes have large, kidney-shaped nuclei and extensive frosted-glass cytoplasm
Name five diagnoses to consider in a patient found to have eosinophilia.
Neoplasm, Asthma, Allergic reaction, Chronic adrenal insufficiency, Parasites (invasive)(NAACP)
A patient is seen for a red, swollen, painful fifth finger. Blood smear reveals increased WBCs with multilobed nuclei. What are they?
Neutrophils, which respond to acute inflammation
A man's blood has neither A nor B antigens. A plasma transfusion is required. Is the risk of ABO-related hemolysis high?
No; the man has type O blood and is a universal recipient of plasma (no risk of transfused anti-A or anti-B antibodies' binding to his RBCs)
What are hypersegmented neutrophils? In which nutrient deficiency are they seen?
Nucleus with 6-plus lobes; seen in vitamin B12/folate deficiency
After maturation, where do B lymphocytes migrate to from the bone marrow?
Peripheral lymphoid tissue (lymph node follicles, white pulp of spleen, other unencapsulated lymphoid tissue)
How do mature platelets form from megakaryocyte precursors?
Small portions of cytoplasm break off from the megakaryocyte
A peripheral smear reveals increased bands (immature neutrophils). What does this reflect?
State of increased myeloid proliferation (bacterial infection, CML)
What is the predominant type of lymphocyte found in the circulation?
T cells, which make up approximately 80% of circulating lymphocytes
On a routine complete blood count, a patient's hematocrit is noted to be high. What does this suggest about the patient's RBC count?
That it is increased (this is called erythrocytosis, or polycythemia)
A patient is in septic shock. Lab studies show increased bacterial LPS. How is this contributing to the patient's pathology?
The lipid A component of bacterial LPS binds to CD14 on macrophages, which can trigger septic shock
How would you describe a peripheral blood smear showing RBCs of varying sizes and shapes?
The smear exhibits anisocytosis (varying sizes) and poikilocytosis (varying shapes)
On the skin of a pt, you see small red lesions that do not blanch with pressure. Name two possible etiologies of these lesions.
These are petechiae, which can be caused by a low platelet count (thrombocytopenia) or dysfunctional platelets
Under the microscope in your lab, you note a neutrophil with several azurophilic granules. What is contained within these granules?
These granules (also known as lysosomes) contain proteinases, acid phosphatase, myeloperoxidase, and β-glucuronidase
What is the function of basophils?
They mediate allergic reaction
Describe the basic function of an erythrocyte.
To carry O2 from the lungs to peripheral tissues and return CO2 from peripheral tissues to the lungs for elimination
What is the main function of leukocytes?
To defend against infection
What is the main role of plasma cells?
To produce large amounts of antibody specific to a particular antigen
Describe the constitution of adult hemoglobin.
Two α-globulins, two β-globulins
Describe the constitution of fetal hemoglobin.
Two α-globulins, two γ-globulins
In which type of hypersensitivity reactions are mast cells involved?
Type I reactions (mast cells mediate allergic reactions in local tissues)
A patient's blood is found to contain the B antigen. Transfusion of blood with which two ABO antigen groups produces a hemolytic reaction?
Types A and AB
A patient's blood is found to contain the A antigen. Transfusion of blood with which two ABO antigen groups produces a hemolytic reaction?
Types B and AB
A peripheral blood smear shows multiple neutrophils (nuclei of six, seven, or even eight lobes). Lab tests needed to diagnose the cause?
Vitamin B12 and folate tests (hypersegmented polys [neutrophils] with five or more lobes are present in deficiencies of either vitamin)
Describe the process of platelet aggregation to form a platelet plug.
When activated by endothelial injury, they aggregate with other platelets and interact with fibrinogen to from a platelet plug
A man's blood has both A and B antigens. A transfusion is needed, but only type AB blood is available. Can it be given without hemolysis?
Yes; people with AB blood are universal recipients of RBCs and can be given any ABO blood type without hemolysis
During weeks 3-8 of embryogenesis, where does erythropoiesis occur?
Yolk sac
How long is the life span of an erythrocyte?
120 days
Which molecule binds less avidly to fetal hemoglobin, giving it a higher affinity to oxygen?
2,3-BPG
What is the life span of a platelet?
8-10 days
What are the contents of small granules in neutrophils?
ALP, collagenase, lysozyme, lactoferrin
What are the contents of the dense granules of platelets?
Adenosine diphosphate, calcium
A patient undergoes splenectomy. Blood loss is minimal. After surgery, platelet count has increased by more than 25%. What happened?
Approximately a third of the platelet pool is normally stored in the spleen—these platelets were released into circulation during surgery
An increase in number of neutrophils indicates what type of infection?
Bacterial
What other cell type do mast cells resemble, both structurally and functionally?
Basophils
Name three types of granulocytes.
Basophils, eosinophils, and neutrophils
Describe the molecular constitution of an RBC.
Biconcave structure with large surface-to-volume ratio for gas exchange, anucleate and lacking organelles
Where are plasma cells found?
Bone marrow
A man's blood smear shows numerous cells with bilobate nuclei and large eosinophilic uniform-sized granules. What diagnoses do you consider?
Eosinophilia in Neoplasia, Asthma, Allergic reaction, Collagen vascular disease, Parasites (NAACP)
Describe the process of mast cell degranulation, starting with antibody binding.
Fc portion of IgE binds to the mast cell membrane, IgE cross-links on antigen stimulation, degranulation occurs
What enzymes are produced by eosinophils?
Histaminase and major basic protein (a helminthotoxin)
What substance activates macrophages?
Interferon-γ