Assignment 3 Flashcards
where are eosinophils derived
bone marrow
what are eosinophils derived from
myeloid progenitor under the influence of IL-5
what secretes IL-5
Th2 cells, mast cells, basophils
what secretes CCL11
epithelial cells and fibroblasts
what role does IL-5 and CCL11 (eotaxin) play in eosinophil
egress (leaving of) eosinophil from the bone marrow and entry into the tissues
half life of eosinophil
8-10 hours
eosinophil percentage of circulating leukocyte in a healthy individual
2-4%
what does eosinophil’s expression of low affinity FcεRII (CD23) do
bind to IgE antibodies themselves bound to epitopes on helminths
define eosinophilia
increase in circulating blood levels of eosinophil
role of major basic protein (MBP) and eosinophil cationic protein (ECP) in relation to helminths
they are very toxic to helminths and are host defense against it
what does eosinophil’s role in host defense against parasite require
antibodies (IgE) generated in adaptive immunity following B cell activation
why are macrophages not as effective as eosinophils in eliminating helminthes
helminths are resistant to destruction by neutrophils and macrophages
three disorders in which there is an increase in circulating eosinophils
allergic asthma, allergic dermatitis, food allergies
what is the immune response to helminthes
During inflammatory conditions with helminths, marked egress of eosinophil from bone marrow and into circulation –> eosinophilia. Eosinophil recognizes helminths indirectly by expressing FcεRII that bind to IgE antibodies themselves which are bound to epitopes on helminths. The interaction triggers degranulation of eosinophil leading to release of major basic protein (MBP) and eosinophil cationic protein (ECP) which are toxic to helminths.
basophils and mast cells arise from
myeloid progenitor in bone marrow
differentiation to basophil occurs in presence of
IL-3
source of IL-3
activated T cells
half life of basophils
2-5 days
percentage of basophils that are circulating leukocytes in normal individual
less than one percent
difference in half life of IgE that is bound to FcεR in comparison to circulating IgE
IgE bound to FcεR: weeks to months
circulating IgE: less than 24 hours
two cytokines released from basophils and mast cells
IL-4 and IL-5
two role of histamine in inflammation
histamine binds to vascular endothelium leading to translocation of P-selectin to the endothelial cell surface
increases vascular permeability
force between FcεR and Fcε
noncovalent force which relies on ionic and hydrophobic bonds (reversible)
what is necessary for cross linking and degranulation when IgE is bound to basophils and mast cells
IgE bound to FcεR is used for binding antigens specific for their FAB region. When two IgE molecules of same specificity are close together, antigen binding results in cross linking and degranulation of basophil and neutrophil which releases histamine and other immune mediators from the granules
