Chapter 6.1 - Leukopenia and Leukocytosis

What other things can cause lymphophenia (decreased number of circulating lymphocytes)?

-Immunodeficiency (DiGeorge Syndrome or HIV) -High cortisol state (induces apoptosis of lymphocytes) -autoimmune destruction (e.g. SLE - remember this can form autoantibodies against RBCs, WBCs, and platelets)

What is a characteristic finding that can distinguish mono from other types of bacteria/viruses that cause a sore throat?

posterior cervical lymphadenopathy

What kind of cell is shown here? What is the cause?

Atypical lymphocyte. You can tell because the nucleus is much bigger than the adjacent RBCs and there is abundant blue cytoplasm (which lymphocytes usually do not have). These are reactive CD8+ T cells from infectious mononucleosis.

What is this organ and what is the pathology? What can this be caused by? How can it be prevented?

This is a splenic rupture caused by mononucleosis. Patients are generally advised to avoid contact sports for one year after infection due to the risk of splenic rupture.

What happens if you mistakenly give ampicillin to someone with mono?

they will develop a rash

To re-emphasize, what is a left shift? What is a marker for it?

a left shift is an increase in the number of immature neutrophils in response to an infection (since the bone marrow is trying to pump as many out as possible). -a marker for it is decreased CD16, since this is present on the Fc receptor, and immature neutrophils do not have as many Fc receptors

How does the high cortisol state cause leukocytosis?

High cortisol state impairs leukocyte adhesion, leading to release of marginated pool of neutrophils (think of the neutrophils like bats in a cave, attached on the edge of blood vessels). -this is why a person on steroids will lead to an increase in WBC count.

What is the classic example of eosinophilia seen in a disease state and why?

Hodgkin's lymphoma (because there is an increase in IL-5). -also can be caused from allergic reactions (type I hypersensitivity) and parasitic infections

What is the screening test for mono? How is a definitive diagnosis made?

Monospot test - detects IgM antibodies that cross-react with horse or sheep RBCs Definitive diagnosis: made by serologic testing for EBV viral capsid antigen.

_____________ refers to a decreased number of circulating neutrophils. What are the 2 major causes? How is this treated?

Neutropenia 1. drug toxicity (e.g. chemotherapy alkylating agents which damage stem cells, decreasing the production of WBCs, especially neutrophils) 2. Severe infection (e.g. gram negative sepsis) - due to most of the neutrophils moving from the blood to the tissues. *treat with GM-CSF or G-CSF (this will boost granulocyte production, which will decrease risk of infection)

EBV can elevate ___________, resulting in hepatitis with hepatomegaly.

liver enzymes

What is the first cell to be damaged by radiation?

lymphocytes (can cause lymphopenia)

Neutrophilic leukocytosis refers to an increase in circulating neutrophils which can be caused by what 3 things?

1. Bacterial infection 2. Tissue necrosis (this induces many neutrophils to go fight infection, which means immature forms of neutrophils are released as well. These immature cells are characterized by decreased Fc receptors (CD16) which means they do not function as well. This is called a left shift) 3. High cortisol state

CD8+ T cell response of IM (infectious mononucleosis) causes what 3 things?

1. Generalized lymphadenopathy (LAD) due to T-cell hyperplasia in the lymph node paracortex (B cells in the cortex of LN, T cells in the paracortex of LN) 2. Splenomegaly due to T cell hyperplasia in the periarterial lymphatic sheath (PALS - remember that is where the T cells are present, within the white pulp part of the spleen) 3. High WBC count with atypical lymphocytes in the blood

A low WBC <____ and is called leukopenia, a high WBC >____ and is called leukocytosis.

5K 10K *a low or high WBC is usually due to decrease or increase in one particular cell lineage

If the monospot test is negative but a patient has the signs and symptoms, what could be the cause?

CMV (instead of EBV)

Basophilia is classically seen in ____________________.

Chronic Myeloid Leukemia

Infectious mononucleosis is caused by an _____ infection (less commonly ______ infection) which results in lymphocytic leukocytosis comprised of reactive ________ cells.

EBV CMV reactive CD8+ T cells

What can the dormacy of the EBV in B cells put a patient at risk for?

Recurrence of mono and B cell lymphoma (especially if immunodeficiency occurs)

What are the causes of lymphocytic leukcytosis? What is the exception to the rule?

Viral infections - T lymphocytes undergo hyperplasia in response to virally infected cells. Bordetella pertussis infection - this is a bacteria that causes lymphocytic leukocytosis. This bacteria produces lymphocytosis-promoting factor which blocks circulating lymphocytes from leaving the blood to enter the lymph node.

What kind of disease states will you see monocytosis?

chronic inflammatory states (e.g. autoimmune and infectious) and malignancy