Leukopenia and Leukocytosis

Question 1

What is the stem cell that is the precursor to all hematopoietic stem cells?

Answer 1

CD34+ hematopoietic stem cell

Question 2

What is the normal wbc count? What is the range and name for low wbc count? Name and range for high WBC count? What is the general cause of changes in WBC count?

Answer 2

5-10K/uL, 5 K/uL leukocytosis; Usually due to increase/decrease in one particular cell lineage

Question 3

What are the two subsets of leukopenia?

Answer 3

Neutropenia and lymphopenia

Question 4

What are 2 causes of neutropenia?

Answer 4

Drug tox with chemoTx (especially to neutrophils), Severe infection - increased neutrophil migration into tissues (decreased circulating count),

Question 5

Tx for neutropenia

Answer 5

GM-CSF or G-CSF to boost granulocytes and therefore neutrophils

Question 6

What are 4 causes of of lymphopenia?

Answer 6

Immunodeficiency (HIV, DiGeorge), High cortisol state (induces apoptosis), autoimmune destruction (SLE), whole-body RTx (lymphocytes highly sensitive to whole body radiation)

Question 7

What are the 5 types of leukocytosis?

Answer 7

Neutrophilic, Monocytosis, Eosinophilic, Basophilic, Lymphocytic

Question 8

Causes of neutrophilic leukocytosis and mechanisms

Answer 8

Bacterial infection/tissue necrosis - release of marginated pool and BM neutrophils (including immature forms (with decreased FC receptors [CD16]); High cortisol state impairs leukocyte adhesion and causes marginated neutrophils to fall into circulation

Question 9

What is the “marginated pool” of neutrophils? What is the mnemonic to remember?

Answer 9

Marginated pool of neutrophils are attached to endothelium. They’re like the bats that hang from the top of the cave.

Question 10

Causes of monocytosis

Answer 10

Chronic inflammatory states and malignancy

Question 11

Causes of eosinophilia

Answer 11

Allergic rxns (Type I hypersensitivity), parasitic infections, Hodgkin lymphoma; driven by eosinophil chemotactic factor

Question 12

Causes of basophilia

Answer 12

CML

Question 13

2 Causes of Lymphocytic Leukocytosis

Answer 13

Viral infections - T cell hyperplasia, Bordetella pertussis - bac produce lymphocyte stimulating factor which blocks lymphocytes from leaving blood vessel

Question 14

What pathogen causes infectious mononucleosis? What kind of leukocytosis occurs? What is the less common cause?

Answer 14

EBV; CD8+ T lymphocytosis; CMV

Question 15

Primary locations of EBV infection

Answer 15

Oropharynx, Liver, B cells

Question 16

Describe CD8+ T cell response to an EBV infection

Answer 16

Generalized lymphadenopathy due to T cell hyperplasia in lymphnode paracortex, splenomegaly due to T cell hyperplasia in periarterial lymphatic sheath (PALS, white pulp), leukocytosis with atypical lymphocytes (CD8+ T cells that are reacting to antigen)

Question 17

What is the test for IM? How long do test results take? If somebody tests negative on this test, what do the results suggest? What is used to make the definitive Dx?

Answer 17

Monospot test detects IgM Abs that cross-react with horse/sheep RBCs. Turns positive in one week. IM due to CMV. Serologic testing for EBC viral capsid antigen.

Question 18

What are complications of Infectious mononucleosis?

Answer 18

Possible splenic rupture, rash if exposed to ampicillin, dormant virus can lead to recurrence and B cell lymphoma (esp. if immunocomp.)