Leukopenia And Leukocytosis

Question 1

What is the hematopoietic stem cell and what are the two stem cells/lineages that come from it?

Answer 1

HP cd34 positive stem cell.
Makes a myeloid stem cell lineage
Makes a lymphoid stem cell lineage

Question 2

Explain the lymphoid stem cell lineage and what it can make?

Answer 2

Makes a B lymphoblast and a T lymphoblast
Each ones makes a naive B cell and naive T cell respectively
Naive B cells turn into plasma cells and naive T cells make either a cd 8 or cd 4 T cell.

Question 3

Explain the myeloid lineage and what is made?

Answer 3

Myeloid stem cell makes 4 different cells: erythroblast, myeloblast, monoblast, and a megakaryoblast.
E makes RBCS; Mye makes neutrophils, basophils and eosinophils; monoblasts make monocytes and mega makes megakaryocytes.

Question 4

What is the normal white blood cell count and what levels define leukopenia and leukocytosis? Also, what is the general principle behind a low or high white blood cell count?

Answer 4

5-10k
Less than 5k
Greater than 10k
A low or high WBC count is usually due to a decrease or increase in one cell type.

Question 5

Top two causes of neutropenia, explain how each one causes neutropenia, and how would we treat the leukopenia?

Answer 5

Drug toxicity, example is chemotherapy. Not only are they taking out the cancer cells, but also rapidly dividing normal cells, so the stem cells. Treat with GMCSF or GCSF.
Severe infection. The idea here is that there are far more neutrophils migrating out of the blood and into the tissue than usual because the infection is so bad.

Question 6

4 causes of lymphopenia, and give examples or explain why it is a cause?

Answer 6

1. Immunodeficiency, Digeorge or HIV
2. High cortisol state like cushings or exogenous use, cortisol induces apoptosis in lymphocytes
3. Autoimmune like lupus, has antibodies against RBCs, WBCs, and platelets
4. Whole body radiation, the lymphocyte is the most sensitive cell in the human body to radiation.

Question 7

3 causes of neutrophilic leukocytosis?

Answer 7

Bacterial infection
Tissue necrosis
High cortisol state

Question 8

What is the high yield point he made about a left shift in a bacterial infection?

Answer 8

The immature neutrophils have decreased Expression of Fc receptors (CD16), which bind immunoglobulin for phagocytosis.

Question 9

Why does a high cortisol state cause high neutrophil levels?

Answer 9

Because the cortisol disrupts the marginal pool of neutrophils that are stuck to the endothelium of the blood vessels and dumps them back into the blood.

Question 10

2 causes of monocytosis?

Answer 10

Chronic inflammation and malignancy

Question 11

3 causes of eosinophilia?

Answer 11

Allergic reactions, parasitic infections, and Hodgkin lymphoma

Question 12

What is the MOA that leads to a rise in eosinophils from Hodgkin lymphoma?

Answer 12

The lymphoma results in a rise in IL5

Question 13

Basophils is classically seen in what disease?

Answer 13

Chronic myeloid leukemia

Question 14

2 causes of lymphocytic leukocytosis, one normal and one cause that is unique and explain why and how it works?

Answer 14

Viral infections is the normal one. CD8 T cells fight infections.
Bordetella pertussis infection. This is unique because it is a bacteria, but the bacteria produces a lymphocytosis promoting factor that blocks lymphocytes from exiting the blood and going to the LN so you get a rise in lymphocytes.

Question 15

How do we characterize/define infectious mononucleosis? What is the less common infection causing it as well?

Answer 15

EBV infection that results in a lymphocytic leukocytosis where CD8 T cells are reacting to the infection.
CMV is less common cause

Question 16

EBV in IM primarily infects what 3 areas of the body causing what in each?

Answer 16

Oropharynx cousin pharyngitis
Liver causing hepatitis
B cells

Question 17

Because of the CD8 T cell response, what 3 things do we see clinically in IM?

Answer 17

Generalized LAD due to tons of T cells in the paracortex of the LN
Splenomegaly due to tons of T cells in the periarterial lymphatic sheath
High WBC count with atypical CD8 T cells in the blood.

Question 18

What is the screening test we can use for IM, what does it detect, what if the test is negative, and what confirmatory test do we do for a definitive diagnosis?

Answer 18

Monospot test.
Detects IgM antibodies that cross react with horse or sheep RBCs called heterophile antibodies
Did it too soon or it means CMV is the culprit
Serologic testing for EBV capsid antigen

Question 19

3 complications of IM?

Answer 19

Spleen can rupture because its huge
Rash if exposed to ampicillin
Virus stays dormant in B cells so risk for recurrence or B cell lymphoma