Hematopoiesis in Disease: Malignancy Classification

Hematopoiesis in Disease: Classification of Hematological Malignancies

Dr. Laura Koumas, PhD

Lecture Topics

• White blood cell disorders
• Leukocytosis
• Leukopenias
• Neutropenias
• Malignant hematopoiesis
• Classification of hematological malignancies

White Blood Cell (WBC) Disorders

• WBCs are also known as leukocytes
• Leukocytes exist throughout the body, inclusive of the lymphatic system and the blood
• Physiologic variations are dependent on age, sex, exercise, emotional state, pregnancy, and sleep patterns.
• Pathologic variations include, but are not limited to, leukopenia, leukocytosis, neutrophilia, eosinophilia, basophilia, monocytosis, and lymphocytosis
• Disorders are severe forms of leukocytosis and leukopenia
• Agranulocytosis, neutropenia, Chediak-Higashi syndrome, acute leukemia, and chronic leukemia are all disorders

Leukocytosis

• Defined as an abnormal increase in the number of circulating WBCs
• Can be a manifestation of a body reaction to a pathological situation
• May arise as a result of exercise, epilepsy (convulsions), emotional stress, pregnancy, and epinephrine administration
• Five main types of leukocytosis exist, with neutrophilia being the most common
• Lymphocytosis, monocytosis, eosinophilia, and basophilia are all main types of leukocytosis

Neutrophilia

• Reactive neutrophilia is produced in response to physiologic or pathologic processes
• With high neutrophil demand, a shift to the left in the differential count occurs, characterized by more immature neutrophils
• Physiologic neutrophilia occurs in newborns, during labor, and after exercise, in addition to convulsions
• Acute infections, inflammatory conditions, and intoxications can cause neutrophilia
• Pathologic neutrophilia occurs in polycythemia (excess RBCs) and myeloid leukemia

Eosinophilia

• Allergic conditions cause eosinophilia, for example bronchial asthma and hay fever
• Skin disease and parasitic infections such as malaria cause eosinophilia
• Pathologic diseases of the hematopoietic system cause eosinophilia
• Chronic myeloid leukemia (CML), polycythemia vera (PV), Hodgkin’s disease, and pernicious anemia all cause eosinophilia
• Eosinophilia occurs after irradiation
• Can occur in sarcoidosis (inflamed tissue formation/granulomas) and rheumatoid arthritis
• Treatment involves addressing the underlying condition

Basophilia

• Can occur after splenectomy
• Related to underlying blood disease
• Chronic Myeloid Leukemia (CML) and polycythemia vera can cause basophilia
• Infections such as smallpox and chickenpox can lead to basophilia
• Basophilic leukemia is a pathologic, but rare, cause of basophilia

Lymphocytosis

• Defined as increased absolute numbers of lymphocytes
• Acute infections such as infectious mononucleosis cause lymphocytosis
• Chronic infections such as tuberculosis and syphilis also cause lymphocytosis
• Viral infections can cause lymphocytosis
• Mumps and German measles can lead to lymphocytosis
• Hematopoietic disorders such as lymphocytosis and lymphoma lead to lymphocytosis
• Lymphocytic leukemia results in lymphocytosis

Monocytosis

• Bacterial infections, like tuberculosis and syphilis, cause monocytosis
• Protozoal and rickettsial infections such as malaria and typhus cause monocytosis
• Lipid storage disease, specifically Gaucher’s disease, can lead to monocytosis
• Granulomatous disease such as sarcoidosis and ulcerative colitis cause monocytosis
• Collagen vascular disease like lupus erythematosus can cause monocytosis
• Rheumatoid arthritis, Chronic Myeloid Leukemia (CML), CMML, Hodgkin's disease and multiple myeloma can cause monocytosis

Leukopenia

• Defined as a decrease in the number of leukocytes found in peripheral blood
• Places individuals at increased risk for infection (immunodeficient)
• Multiple causes:
  • Infections: bacterial, viral, protozoal
  • Hematopoietic disorders: aplastic anemia, CML
  • Chemical agents; benzene, mustard gas, analgesics, antihistamines, antithyroid drugs
  • X-ray radiations
  • Anaphylactic shock
  • Liver cirrhosis

Agranulocytosis

• A serious disease characterized by a decrease/low number in the absolute number of circulating neutrophils
• Neutrophil count in neutropenia is defined as <1500 cells/ µl
• Severe neutropenia occurs at <500 cells/ µl
• Interchangeable terms include agranulocytosis, neutropenia, and granulocytopenia
• Can be temporary (acute) or last 3+ months (chronic), impacting children and adults
• Primary/Congenital neutropenia is associated with germline defects
• Secondary neutropenia can be caused by a post-infectious state, medications, immune disorder, or hematological malignancy
• Individuals have an increased risk for life-threatening infections

Neutropenia Types

1. Congenital - caused by monogenic disorders that leads to severe neutropenia, seen most commonly in babies and young children

• Examples include are severe congenital neutropenia and Kostmann's syndrome, where neutrophils in the bone marrow may not develop fully leading to life-threatening infections.

2. Idiopathic - has an unknown cause, it affects children and adults.
3. Cyclic - Autosomal dominant; occurs every 3 weeks, potentially lasting 3-6 days due to the cyclical nature of cell production in a persons marrow; affects both children and adults.
4. Autoimmune - the most common cause of neutropenia in infants and young children, caused by autoimmune anti-neutrophil antibodies; sometimes seen in adults aged 20-40 years (mostly women).
5. Febrile - a severe side effect for people with cancer who are treated with chemotherapy, related to dangerous infections from suppressed immune system due to the treatment.

Severe Congenital Neutropenia

• Severe congenital neutropenias are a heterogeneous group of rare haematological diseases
• Characterized by impaired maturation of neutrophils (usually halted at the promyelocyte stage)
• Frequent pathogenic defects are autosomal dominant mutations in ELANE (codes neutrophile elastase) which = severe congenital neutropenia
• Autosomal recessive defects: Mutations in HAX1 (Kostman syndrome) which activates the granulocyte colony-stimulating factor (G-CSF) signalling pathway.
• Severe congenital neutropenias cause predisposal to myelodysplastic syndromes or acute myeloid leukaemia (AML).
• Malignant progression includes acquired mutations in CSF3R (G-CSF receptor) with other leukemia-associated genes such as RUNX1

Elastase-dependent congenital neutropenia

• Neutrophil elastase (NE) is secreted by neutrophils during inflammation and aids destruction of bacteria and host tissue
• NE is produced as a zymogen and activated after translation, during the promyelocytic stage of granulopoiesis in bone marrow.
• Neutrophil development stages occur in the bone marrow with differentiation blockade at promyelocyte stge is highlighted
• ELANE frameshift mutations induce cellular surveillance pathways to safeguard the quality of transcripts and preven NE production
• NE-induced neutropenia mutations cause mutational suppression

Neutrophil Migration and Function

• Neutrophil migration and function are related to emigration from the bone marrow
• WHIM syndrome can lead to these migration and function issues
• Some disease syndrome genes, include:
• Severe congenital neutropenia, ELA2, CSF3R, Gfl1
• Kostmann syndrome, HAX1
• Cyclic neutropenia, ELA2
• Schwachman-Diamond syndrome, SBDS
• Glycogen storage disease Ib, SLC37A4

WHIM syndrome

• Primary Immunodeficiency described ad WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, occurring from an autosomal dominant immune deficiency
• WHIM Syndrome is characterized by the retention of mature neutrophils in the bone marrow (myelokathexis)
• It leads to occasional hypogammaglobulinemia
• Myelokathexis causes retention of neutrophils in the BM
• WHIM is associated with an increased risk for bacterial infections
• Causes Susceptibility to HPV-induced lesions (cutaneous warts, genital dysplasia and invasive mucosal carcinoma).

WHIM details

• Is caused by accumulation of mature and degenerating neutrophils in the bone marrow, caused uniquely by a non-cyclic severe form of congenital neutropenia
• Causes: neutrophil failure to exit the bone marrow, leads to peripheral neutropenia
• Neutrophil egress and distribution is determinied by the balance of CXCR2 release signals and CXCR4 retention signals
• Therefore both the gain or loss of function of the genes causes myelokathexis, but more specifically loss-of-function CXCR2 mutations and gain-of-function CXCR4

WHIM Genetics

• WHIM syndrome genetic mutations in CXCR4 will create abnormal trafficking of white blood cells
• CXCR4 Mutations lead to prematrue truncations in the protein that results in excessive signalling despite normal ligand levels, CXCL12
• “Gain of function” mutations from excessive“on” signaling decreases the ability of neutrophils to move from BM to the peripheral blood and perform immunosurveillance
• In other diseases, such as cancer, the CXCL12/CXCR4 pathway has been found to broadly play a role in disrupted immune cell trafficking

Diagnosing WHIM

• Neutrophil myelokathexis morphology includes hypercondensed chromatin
• Long thin chromatin can separate nuclearl lobes with variable cytoplasmic vacuolisation.
• myeloid hyperplasia with non-para trabecular aggregates of neutrophils with neutrophil apoptosis indicate WHIM
• Bone marrow aspirate smears, as well as core biopies with myeloid hyperplasia are good diagnostic techniques because periperal neutropenia indicates a lack of neutrophil retention in the marrow

Issues with Myeloid Maturation

• Dyspoiesis is one issue, or ineffective maturation. Examples genes affected at this level are ELF1, LYSY, or USB1 Accumulation of early mylocyte precursers happens, especially with mutation with gene TAZ

Diagnosis for Chromic Neutropenia

• Is based on clinical manifestation, neutrophil count, bone marrow examinations, as well as genetic and immunological analyses
• Daily subcutaneous G-CSF administration is the standard treatement to raise the cell count, reduce infections and drastic improvement of quality of life.
• Haematopoietic stem cell transplantation is the alternative treatment to severe cases.
• Regular clinical assessments (including yearly bone marrow exams) help monitor treatment. Detect chromosomal abnormalities such as monosomy/trisomy as well as pre-leukaemic mutations can be identified.

Haematology Cell Lineages and Malignancies

• Hematopoetic stem cells give rise to lymphoid progenitor, as well as myeloid Progenitor
• These progenitor cells each yield a variety of differentiated cells.
  • Lymphoid lineages: include Natural killer cells, T-lymphocytes which differentiate to T-cells, B-lymphocytes which differentiate to plasma cells .
  • Myeloid lineages: Erythroblast differentiatiate to red blood cells, and megakaryocytes yield platelets. Basophil, Eosinophil, Monocyte, and Neutrophil also derive from myeloid linneages
• Mutuations along these paths lead to many haemo malignancies ie: Chronic Myeloid Leukemia, Acute myeloid Leukemia, chronic or acute lymphoblastic leukemia, multiple myeloma

Normal vs Malignant Hematopoiesis

• Normal hematopoiesis is an ordered multi-step process under network and enviornmental cue control in bone marrow.
• With malignant hematological disorders , such as acute leukemias (ALL), undifferentiation and precursors of the lymphoid or myeloid series lets the clone gorw.
• This happens at the expense of normal hem. and blood cell prod
• Leukemic clones compete for niche resources which also alters the bone marrow; overall pathobiology is impacted
• For leukemic initiation to happen, the normal haemato, the production of leuk cells, and the competition needs to work together.

Stem and Progen Cells

• All begin with normal stem cells that differentiate into progenitors, which then make differentiated cells
• Mutations etc can cause normal hemopoetic cells to develop into leukiem stem cells, which differentiate into leukiemic progenitor and then blast cells
• These cells replace the function of existing ones in bone marrow.

Tumor Microenvironment

• Normal hem. is under the influence of cytokines, integrins, and the matrix
• Tumore cells also work among normal elements but they all also use signals from the matrix
• The play between these 2 enviornments cause inverse leukemic/normal relationship by disrupting the HSC-niche

Cellular Model of Leukemia

• Basically healthy tissue will lose cells and functions as cancer sets in. Stem cells give way to cancerous ones, but also preogrenitor/blasts, etc become cancerous
• Over time more of the differentiated stem cells and related precursors become impacted, to the degrredtion of healthy cells that are necessary for survivial.

Luekemic Stem Cells Details

• Chemoresistant leukemia cells( LSCs), are a minority population that initiate leukemia.
• The cells excessively proliferate through self-renewal instead of the health cells
• LSCs also have abnl signalling, immune evasion from dysregulated cytokines
• This retains it at the stem cell niche.
• High CXCL12 binding to CXCR4 maintains cells. This with SCF to C-Kit does this, while also giving some self-renewal.
• Cells are kept at a certain amount while conferring some of of the chemo resitance.

Leukemia Remission

• Chemotherapy targets proliferating leukemic cells allowing for remission
• In the event of relapse, it may be because initial clone was resistant or an undetectable before line may have been preasent
• Imp to consider diagnostics, look at normal vs differentiation char, and regular monitior

Malignancy

• HSCs differentiate to myeloid vs lymphoid progenitor
• AbNL Haemtopoesis happens with genetics, viral, stress , or after radiation from other treatment
• All will impact blood. Can occur after radiation or other treatment

Categories of Haemat Malign

• Split broadly, but with each can be more types
• 1 common blood cancers
• Lymph - tumors occur at the lymph, in lumps
• Leukeamia - develop in blood then blood spreads
• Myeloma - tumors develop at plasma cells and form in marrow

Leukemia Summary

• Leukemia includes the production of leukocytes which suppress normal blood cells
• In those cases pt develops cytopenaies
• there's 60kk cases a year in US w/ 24k deaths a year

Leukemia Category

• Acute - rapid progression in BM as functoinless BM cells are high
• Chronic - slow progression, may have more abnormal cell but low cases, often
• myeloid or Lymph

Leukemia Types

• See breakdown chart
• Lymph - lyphoids and in children mostly
• Myeloid - in adult and cell grows fast
• Lymph - slows, adults, lymphoid
• Myeloid, cells grow slow but in adults

leukemia symptoms

Fatigue, wt loss, breathing issues, tendernes and aches, node swelling. Splean and liver swells too, often can easily bruise and have nose blee ds

Abnormal WBC

• Lab findings include many abnl or lack of cell amount in BM, low rbc count and other indicators of low cellcount, hgb

More leukemia symptoms

All are abnl Prominent nucleol, lots large, fine chromatin, and bigcyt

AML

• Most heterosgenous set of precursor, cell of myeoid
• Muts per case, 15-20 percent of childhood, and more if adult.

Maturation Process

• As meloid differenitase markers change one gets to lose or gain
• Cell halt along route of change, causes many AML cells

AML diagnosis

Fab- American Classication used Need high levels of each cell

AML French Am Class

Use of 8 levels to mark AML presence and morpholgoicy

Acute Lymph Leukemia - ALL

• Abnnornmal profoeration, 76 in children mostly
• Fab char with morphology
• ALL-I mostly unifocem celles
• ALL-2 largger varied
• ALL-ls large buly
• Linked also to genenetic muations

What Is ALL

• Occurs when the body makes nonfunctional or not enough white blood cells in BM Is in the B cells by which it can be activated or surpressed with B CELL
• The T cells are normal but do not proliferate normally

Lymphoma

• Malgin that clusters in the nodes, and develop in system
• HD or nhd exist, more on the cells it develops

Types L lymphoma

low = SLL, CLL, Splenic, hair cell More grade aggressive = B and Burkitt (dlbdl)

Germline mutation origin

• Can be centroblasts and blastcs
• B cell receptor leads to MM
• Plasma from GC has it lead to Dlbl B cell
• Memory from it lead to lymphoplasma

Details

• Lymphs need mut to cause

Lymphomas and Leukemia

• All cause issues to these systems
• See flowchart, note all cells and the process

Myeloma

• An abnl dev of plasmaa causing issues from tumors in marrow
• Often a high issue. Constant monting
• Also affect cells causing disabil

Plasmast Characteristics

• Abnl prod of cells, with IgM as well