Chapter 13.2--Reactive proliferations of White cells and lymph nodes Flashcards
Leukocytosis
- increase in the number of white cells in blood
- common reaction to inflammatory states
Pathogenesis of leukocytosis–peripheral blood leukocyte count is influenced by several factors including:
- size of myeloid and lymphoid precursor and storage cell pools in bone marrow, thymus, circulation and peripheral tissues
- rate of release of cells from storage pools into circulation
- proportion of cells that are adherent to blood vessel walls at any time (marginal pool)
- rate of extravasation of cells from blood into tissues
Leukocytosis–increased production in marrow caused by?
- chronic infection or inflammation (growth factor dependent)–most important!!
- paraneoplastic (Hodgkin lymphoma, growth factor dependent)
- Myeloproliferative disorders (chronic myelooid leukemia; growth factor-independent)
Leukocytosis–increased release from marrow stores caused by?
- Endotoxemia
- Infection
- Hypoxia
Leukocytosis–decreased margination caused by?
- exercise
- catecholamines
Leukocytosis–decreased extravasation into tissues caused by?
-Glucocorticoids
Leukocyte homeostasis is maintained by?
-cytokines, growth factors and adhesion molecules through their effects on the committment, proliferation, differentiation and extravasation of leukocytes and progenitors
Acute infection
-rapid increase in the egress of mature granulocytes from bone marrow pool, an alteration that may be mediated through the effects of TNF and IL-1
-if infection or inflammatory process is prolonged,
- IL-1, TNF and other inflammatory mediators stimulate macrophages, bone marrow stromal cells and T cells to produce increased amounts of hematopoetic growth factors which enhance the proliferation and differentiation of committed granulocytic progenitors and cause a sustained increase in neutrophil production
IL-5 mainly stimualates? G-CSF induces?
- IL-5=eiosinophil production
- G-CSF=neutrophilia
In sepsis or severe inflammatory disorders (like Kawasaki disease), leukocytosis is often accompanied by?
-morphologic changes in neutrophils like toxic granulations, Dohle bodies and cytoplasmic vacuoles
Toxic granules
-coarser and darker than the normal neutrophilic grnaules–represent abnormal azurophilic (primary granules)
Dohle bodies
-patches of dilated ER that appear as sky-blue cytoplasmic puddles
Usually its easy to distinguish reactive vs. neoplastic leukocytosis; but when do they become uncertain?
- Acute viral infections, esp in children can cause the appearance of large numbers of activated lymphocytes that resemble neoplastic lymphoid cells
- At other times, esp in severe infections, many immature granulocytes appear in the blood, mimicking myeloid leukemia (leukemoid reaction)
- Special lab studies helpful in distinguishing reactive and neoplastic leukocytosis
Types of leukocytosis
- Neutrophilic leukocytosis
- Eiosinophilic leukocytosis
- Basophilic leukocytosis
- Monocytosis
- Lymphocytosis
Neutrophilic leukocytosis
-acute bacterial infections, esp those cuased by pyogenic orgnaisms; sterile inflammation caused by for example, tissue necrosis (myocardial infarction, burns)
Eiosinophilic leukocytosis (eiosinophilia)
-allergic disorders like asthma, hay fever, parasitic infections; drug reactions; certain malignancies (Hodkin and some non-Hodgkin lymphomas); autoimmune disorders (pephigus, dermatitis herpetiformis) and some vasculitidies; atheroembolic disease (transient)
Basophilic leukocytosis (basophilia)
-rare, indicative of myeloproliferative disease (chronic myelogenous leukemia)