Chapter 13 Robbins Flashcards
What can stimulate HSCs in marrow to move from stem cell niches?
G-CSF
Response to stress
Marrow response to short term needs
Controlled by growth factors that act on committed progenitors
Growth factors acting on EARLY committed progenitors
KIT ligand and FLT3-ligand
Growth factors acting on restricted progenitors
Erythropoietin, GM-CSF, G-CSF, and thrombopoietin
Distortion of marrow architecture can lead to
Abnormal release of immature precursors (leukoerythroblastosis)
Fat cells increase in bone marrow in
Hypoplastic states
And decrease in neoplastic or hyperplastic states
Leukopenia usually results from
Decreased number of neutrophils
Usually associated with decreased function of granulocytes
Lymphopenia most commonly from
HIV, glucocorticoid therapy, autoimmune disorders, malnutrition and viral infections
Usually a redistribution (to LN and tissue) rather than a decrease in number
Cause of neutropenia
Inadequate/ineffective granulopoiesis
Increased destruction/sequestions
Suppression of HSCs causing neutropenia
Aplastic anemia, tumors, granulomatous disease
Accompanied by anemia and thrombocytopenia
Suppression of granulocyte committed precursors causing neutropenia
Drug toxicity
Ineffective hematopoiesis causing neutropenia
Megaloblastic anemias, myelodysplastic syndromes (precursors die in the marrow)
Congenital syndromes causing neutropenia
Kostmann syndrome
Impairs differentiation of granulocytes
Immune mediated destruction of neutrophils
Can be idiopathic, associated with a disease like SLE, or drug toxicity related
Effect of splenomegaly on neutrophils
Increased sequestration
Sometimes associated with anemia and thrombocytopenia
Increased peripheral utilization of neutrophils occurs with
Bacterial, fungal and rickettsial infections
Most common cause of agranulocytosis
Drug toxicity
Red cells and platelets also effected
Aminopyrine, chloramphenicol, sulfonamides, chlorpromazine, thiouracil, and phenylbutazone
Chlorpromazine effect on neutrophils
Direct toxicity
Sulfonamide effect on neutrophils
Antibody mediated destruction
LGL leukemia effect on neutrophils
Monoclonal proliferation of lymphocytes suppresses production of neutrophils
Morphological consequences of neutropenia
Compensatory marrow hyperplasia Increased infections (candida and aspergillus)
Clinical features of neutropenia
Related to infection - serious infections when under count of 500
Fever, malaise, and chills
Peripheral leukocyte count
Size of precursor and storage pools
Rate of release into circulation
Size of marginal pool (adhering to BV)
Rate moving into tissues
Most important cause of neutrophilic leukocytosis
Infection
Mediated by IL-1 and TNF
Increased production of neutrophils in marrow
Chronic infection or inflammation
Paraneoplastic
Myeloproliferative
Increased release of neutrophils
Infection
Endotoxemia
Hypoxia
Decreased margination of neutrophils
Exercise
Catecholamines
Decreased extravasation
Glucocorticoids
IL-5 specifically stimulates
Eosinophils
G-CSF specifically stimulates
Neutrophils
In sepsis or severe inflammation leukocytosis in accompanied by
Morphological changes in neutrophils
Toxic granulations
Dohle bodies
Cytoplasmic vacuoles
Toxic granules
Appear coarser and darker
Abnormal primary granules
Dohle bodies
Patches of dilated endoplasmic reticulum that appear as sky-blue cytoplas- mic “puddles”
Reactive vs Neoplastic leukocytosis
Usually able to distinguish except in cases of acute viral infection in kids or severe infections leading to immature cells in the blood like in a myeloid leukemia (leukemoid reaction)
Neutrophilic leukocytosis caused by
Acute bacterial
Sterile inflammation
Eosinophilic leukocytosis caused by
Allergic disorders
Malignancy
AI disorders
Basophilic leukocytosis is
Very RARE
Myeloproliferative disease
Monocytosis caused by
Chronic infections
AI disorders
Inflammatory bowel disease
Lymphocytosis associated with
Monocytosis
Viral infections
Germinal centers
Pale staining, seen when primary follicles enlarge
B cells acquire capacity to make high affinity antibodies
T cells in LN
Reside in paracortical zones
Undergo hyperplasia during immune response
Acute nonspecific lymphadenitis
LN are swollen with large, reactive germinal centers
Pyogenic organisms -> neutrophils -> necrosis/pus
Seen more in cervical and mesentary
Follicular hyperplasia
Chronic nonspecific lymphadenitis - Result of humoral response
**Tingible body macrophages
RA, toxo, HIV
(looks similar to follicular lymphoma but architecture is intact and everything more organized)
Paracortical hyperplasia
Chronic - T cell response (viral infection)
T cell zones are bigger and contain immunoblasts (larger)
Sinus histiocytosis
Seen in LN draining cancer (breast cancer)
Chronic LN inflammation
Common in axillary and inguinal
LN are nontender and large/hard
Tertiary lymphoid organs
Seen with chronic immune reactions
Immune cell collections in non-lymphoid tissue
Classic ex. include RA (B cells in joints) and chronic gastritis from helicobacter pylori
Hemophagocytic lymphohistiocytosis (HLH)
Systemic activation of macrophages and CD8+ cytotoxic T cells -> cytopenia and shock (mediators initiate systemic inflammation)
Something to do with toxic granules of NK and cytotoxic T cells
Most common trigger of HLH
EBV (infection)
Clinical features of HLH
Acute febrile illness, hepatosplenomegaly
Anemia, thrombocytopenia, high levels of plasma ferritin and soluble IL-2 receptor
Treat with immunosuppressive therapy -> poor prognosis especially if not treated
When are proto-oncogenes often activated in lymphoid cells?
Antigen receptor gene rearrangement and diversification
- Increased AID expression -> induce MYC/Ig translocations
- Increased expression of BCL6
- Precursor B and T cells express VDJ recombinase -> cuts DNA
Pro growth mutations
Tyrosine kinase
MYC
Self renewal mutations
MLL translocation, PML-RARA fusion gene
Pro survival mutations
BCL2 translocation
Diseases that cause genetic instability
Bloom syndrome, Fanconi anemia, and ataxia telangiectasia (acute leukemia)
Downs and Type I NF (childhood leukemia)
Lymphotrophic viruses
Human T-cell leukemia virus-1 (HTLV-1), EBV, and Kaposi sarcoma herpesvirus/human herpesvirus-8
Chronic inflammation and lymphoid neoplasia
H. pylori -> gastic B cell lymphoma
Celiac and breast implants -> T cell lymphomas (local)
HIV -> germinal center B cell lymphomas (systemic)
Radiation therapy and cancer
Increased risk of myeloid and lymphoid neoplasms
Smoking and white cell cancer
Increased risk of acute myeloid leukemia